diff --git a/src/PrayerTracker.Data/DataAccess.fs b/src/PrayerTracker.Data/DataAccess.fs
index 2abcde8..ef7169e 100644
--- a/src/PrayerTracker.Data/DataAccess.fs
+++ b/src/PrayerTracker.Data/DataAccess.fs
@@ -2,6 +2,7 @@
 module PrayerTracker.DataAccess
 
 open System.Linq
+open NodaTime
 open PrayerTracker.Entities
 
 [<AutoOpen>]
@@ -24,7 +25,6 @@ module private Helpers =
         if pageNbr > 0 then q.Skip((pageNbr - 1) * pageSize).Take pageSize else q
 
 
-open System
 open Microsoft.EntityFrameworkCore
 open Microsoft.FSharpLu
 
@@ -90,12 +90,14 @@ type AppDbContext with
 
     /// Get all (or active) requests for a small group as of now or the specified date
     member this.AllRequestsForSmallGroup (grp : SmallGroup) clock listDate activeOnly pageNbr = backgroundTask {
-        let theDate = match listDate with Some dt -> dt | _ -> grp.LocalDateNow clock
+        let theDate = match listDate with Some dt -> dt | _ -> SmallGroup.localDateNow clock grp
         let query =
             this.PrayerRequests.Where(fun req -> req.SmallGroupId = grp.Id)
             |> function
             | q when activeOnly ->
-                let asOf = DateTime (theDate.AddDays(-(float grp.Preferences.DaysToExpire)).Date.Ticks, DateTimeKind.Utc)
+                let asOf =
+                    (theDate.AtStartOfDayInZone(SmallGroup.timeZone grp) - Duration.FromDays grp.Preferences.DaysToExpire)
+                        .ToInstant ()
                 q.Where(fun req ->
                         (   req.UpdatedDate > asOf
                          || req.Expiration  = Manual
diff --git a/src/PrayerTracker.Data/Entities.fs b/src/PrayerTracker.Data/Entities.fs
index 62418fc..b38d84f 100644
--- a/src/PrayerTracker.Data/Entities.fs
+++ b/src/PrayerTracker.Data/Entities.fs
@@ -1,7 +1,5 @@
 namespace PrayerTracker.Entities
 
-// fsharplint:disable RecordFieldNames MemberNames
-
 (*-- SUPPORT TYPES --*)
 
 /// How as-of dates should (or should not) be displayed with requests
@@ -633,10 +631,10 @@ and [<CLIMutable; NoComparison; NoEquality>] PrayerRequest =
         SmallGroupId : SmallGroupId
         
         /// The date/time on which this request was entered
-        EnteredDate : DateTime
+        EnteredDate : Instant
         
         /// The date/time this request was last updated
-        UpdatedDate : DateTime
+        UpdatedDate : Instant
         
         /// The name of the requestor or subject, or title of announcement
         Requestor : string option
@@ -664,8 +662,8 @@ with
             RequestType    = CurrentRequest
             UserId         = UserId Guid.Empty
             SmallGroupId   = SmallGroupId Guid.Empty
-            EnteredDate    = DateTime.MinValue
-            UpdatedDate    = DateTime.MinValue
+            EnteredDate    = Instant.MinValue
+            UpdatedDate    = Instant.MinValue
             Requestor      = None
             Text           = "" 
             NotifyChaplain = false
@@ -674,20 +672,6 @@ with
             Expiration     = Automatic
         }
     
-    /// Is this request expired?
-    member this.IsExpired (curr : DateTime) expDays =
-        match this.Expiration, this.RequestType with
-        | Forced, _ -> true
-        | Manual, _ 
-        | Automatic, LongTermRequest
-        | Automatic, Expecting  -> false
-        | Automatic, _ -> curr.AddDays(-(float expDays)).Date > this.UpdatedDate.Date // Automatic expiration
-
-    /// Is an update required for this long-term request?
-    member this.UpdateRequired curr expDays updWeeks =
-        if this.IsExpired curr expDays then false
-        else curr.AddDays(-(float (updWeeks * 7))).Date > this.UpdatedDate.Date
-
     /// Configure EF for this entity
     static member internal ConfigureEF (mb : ModelBuilder) =
         mb.Entity<PrayerRequest> (fun it ->
@@ -759,19 +743,6 @@ with
             Users          = ResizeArray<UserSmallGroup> ()
         }
 
-    /// Get the local date for this group
-    member this.LocalTimeNow (clock : IClock) =
-        if isNull clock then nullArg (nameof clock)
-        let tzId = TimeZoneId.toString this.Preferences.TimeZoneId
-        let tz =
-            if DateTimeZoneProviders.Tzdb.Ids.Contains tzId then DateTimeZoneProviders.Tzdb[tzId]
-            else DateTimeZone.Utc
-        clock.GetCurrentInstant().InZone(tz).ToDateTimeUnspecified ()
-
-    /// Get the local date for this group
-    member this.LocalDateNow clock =
-        (this.LocalTimeNow clock).Date
-    
     /// Configure EF for this entity
     static member internal ConfigureEF (mb : ModelBuilder) =
         mb.Entity<SmallGroup> (fun it ->
@@ -855,7 +826,7 @@ and [<CLIMutable; NoComparison; NoEquality>] User =
         Salt : Guid option
         
         /// The last time the user was seen (set whenever the user is loaded into a session)
-        LastSeen : DateTime option
+        LastSeen : Instant option
         
         /// The small groups which this user is authorized
         SmallGroups : ResizeArray<UserSmallGroup>
@@ -900,7 +871,7 @@ with
         mb.Model.FindEntityType(typeof<User>).FindProperty(nameof User.empty.Salt)
             .SetValueConverter (OptionConverter<Guid> ())
         mb.Model.FindEntityType(typeof<User>).FindProperty(nameof User.empty.LastSeen)
-            .SetValueConverter (OptionConverter<DateTime> ())
+            .SetValueConverter (OptionConverter<Instant> ())
 
 
 /// Cross-reference between user and small group
@@ -947,4 +918,44 @@ with
             .SetValueConverter (Converters.UserIdConverter ())
         mb.Model.FindEntityType(typeof<UserSmallGroup>).FindProperty(nameof UserSmallGroup.empty.SmallGroupId)
             .SetValueConverter (Converters.SmallGroupIdConverter ())
-        
\ No newline at end of file
+
+
+/// Support functions for small groups
+module SmallGroup =
+    
+    /// The DateTimeZone for the time zone ID for this small group
+    let timeZone group =
+        let tzId = TimeZoneId.toString group.Preferences.TimeZoneId
+        if DateTimeZoneProviders.Tzdb.Ids.Contains tzId then DateTimeZoneProviders.Tzdb[tzId]
+        else DateTimeZone.Utc
+    
+    /// Get the local date/time for this group
+    let localTimeNow (clock : IClock) group =
+        if isNull clock then nullArg (nameof clock)
+        clock.GetCurrentInstant().InZone(timeZone group).LocalDateTime
+
+    /// Get the local date for this group
+    let localDateNow clock group =
+        (localTimeNow clock group).Date
+    
+
+
+/// Support functions for prayer requests
+module PrayerRequest =
+    
+    /// Is this request expired?
+    let isExpired (asOf : LocalDate) group req =
+        match req.Expiration, req.RequestType with
+        | Forced, _ -> true
+        | Manual, _ 
+        | Automatic, LongTermRequest
+        | Automatic, Expecting  -> false
+        | Automatic, _ ->
+            // Automatic expiration
+            asOf.PlusDays -group.Preferences.DaysToExpire > req.UpdatedDate.InZone(SmallGroup.timeZone group).Date
+
+    /// Is an update required for this long-term request?
+    let updateRequired asOf group req =
+        if isExpired asOf group req then false
+        else asOf.PlusWeeks -group.Preferences.LongTermUpdateWeeks
+                >= req.UpdatedDate.InZone(SmallGroup.timeZone group).Date
diff --git a/src/PrayerTracker.Data/PrayerTracker.Data.fsproj b/src/PrayerTracker.Data/PrayerTracker.Data.fsproj
index 0fbe868..09642d4 100644
--- a/src/PrayerTracker.Data/PrayerTracker.Data.fsproj
+++ b/src/PrayerTracker.Data/PrayerTracker.Data.fsproj
@@ -17,7 +17,7 @@
     <PackageReference Include="Giraffe" Version="6.0.0" />
     <PackageReference Include="Microsoft.FSharpLu" Version="0.11.7" />
     <PackageReference Include="NodaTime" Version="3.1.0" />
-    <PackageReference Include="Npgsql.EntityFrameworkCore.PostgreSQL" Version="6.0.5" />
+    <PackageReference Include="Npgsql.EntityFrameworkCore.PostgreSQL" Version="6.0.6" />
     <PackageReference Update="FSharp.Core" Version="6.0.5" />
   </ItemGroup>
 
diff --git a/src/PrayerTracker.UI/Layout.fs b/src/PrayerTracker.UI/Layout.fs
index 24b2a93..a9e6277 100644
--- a/src/PrayerTracker.UI/Layout.fs
+++ b/src/PrayerTracker.UI/Layout.fs
@@ -255,13 +255,13 @@ let private messages viewInfo =
         |> List.singleton
 
 
-open System
+open NodaTime
 
 /// Render the <footer> at the bottom of the page
 let private htmlFooter viewInfo =
     let s          = I18N.localizer.Force ()
     let imgText    = $"""%O{s["PrayerTracker"]} %O{s["from Bit Badger Solutions"]}"""
-    let resultTime = TimeSpan(DateTime.Now.Ticks - viewInfo.RequestStart).TotalSeconds
+    let resultTime = (SystemClock.Instance.GetCurrentInstant () - viewInfo.RequestStart).TotalSeconds
     footer [ _class "pt-footer" ] [
         div [ _id "pt-legal" ] [
             a [ _href "/legal/privacy-policy" ] [ locStr s["Privacy Policy"] ]
diff --git a/src/PrayerTracker.UI/PrayerRequest.fs b/src/PrayerTracker.UI/PrayerRequest.fs
index 1da8ad9..9c766a5 100644
--- a/src/PrayerTracker.UI/PrayerRequest.fs
+++ b/src/PrayerTracker.UI/PrayerRequest.fs
@@ -154,23 +154,22 @@ let maintain (model : MaintainRequests) (ctx : HttpContext) viewInfo =
     let l     = I18N.forView "Requests/Maintain"
     use sw    = new StringWriter ()
     let raw   = rawLocText sw
-    let now   = model.SmallGroup.LocalDateNow (ctx.GetService<IClock> ())
-    let prefs = model.SmallGroup.Preferences
+    let group = model.SmallGroup
+    let now   = SmallGroup.localDateNow (ctx.GetService<IClock> ()) group
     let types = ReferenceList.requestTypeList s |> Map.ofList
-    let updReq (req : PrayerRequest) =
-        if req.UpdateRequired now prefs.DaysToExpire prefs.LongTermUpdateWeeks then "cell pt-request-update" else "cell"
-        |> _class 
-    let reqExp (req : PrayerRequest) =
-        _class (if req.IsExpired now prefs.DaysToExpire then "cell pt-request-expired" else "cell")
-    let vi = AppViewInfo.withScopedStyles [ "#requestList { grid-template-columns: repeat(5, auto); }" ] viewInfo
+    let vi    = AppViewInfo.withScopedStyles [ "#requestList { grid-template-columns: repeat(5, auto); }" ] viewInfo
     /// Iterate the sequence once, before we render, so we can get the count of it at the top of the table
     let requests =
         model.Requests
         |> List.map (fun req ->
-            let reqId     = shortGuid req.Id.Value
-            let reqText   = htmlToPlainText req.Text
-            let delAction = $"/prayer-request/{reqId}/delete"
-            let delPrompt =
+            let updateClass  =
+                _class (if PrayerRequest.updateRequired now group req then "cell pt-request-update" else "cell")
+            let isExpired    = PrayerRequest.isExpired now group req
+            let expiredClass = _class (if isExpired then "cell pt-request-expired" else "cell")
+            let reqId        = shortGuid req.Id.Value
+            let reqText      = htmlToPlainText req.Text
+            let delAction    = $"/prayer-request/{reqId}/delete"
+            let delPrompt    =
                 [   s["Are you sure you want to delete this {0}?  This action cannot be undone.",
                         s["Prayer Request"].Value.ToLower() ].Value
                     "\\n"
@@ -183,7 +182,7 @@ let maintain (model : MaintainRequests) (ctx : HttpContext) viewInfo =
                     a [ _href $"/prayer-request/{reqId}/edit"; _title l["Edit This Prayer Request"].Value ] [
                         iconSized 18 "edit"
                     ]
-                    if req.IsExpired now prefs.DaysToExpire then
+                    if isExpired then
                         a [ _href  $"/prayer-request/{reqId}/restore"
                             _title l["Restore This Inactive Request"].Value ] [
                             iconSized 18 "visibility"
@@ -200,11 +199,11 @@ let maintain (model : MaintainRequests) (ctx : HttpContext) viewInfo =
                         iconSized 18 "delete_forever"
                     ]
                 ]
-                div [ updReq req ] [
+                div [ updateClass ] [
                     str (req.UpdatedDate.ToString(s["MMMM d, yyyy"].Value, Globalization.CultureInfo.CurrentUICulture))
                 ]
                 div [ _class "cell" ] [ locStr types[req.RequestType] ]
-                div [ reqExp req ] [ str (match req.Requestor with Some r -> r | None -> " ") ]
+                div [ expiredClass ] [ str (match req.Requestor with Some r -> r | None -> " ") ]
                 div [ _class "cell" ] [
                     match reqText.Length with
                     | len when len < 60 -> rawText reqText
@@ -316,7 +315,7 @@ let view model viewInfo =
     let s         = I18N.localizer.Force ()
     let pageTitle = $"""{s["Prayer Requests"].Value} • {model.SmallGroup.Name}"""
     let spacer    = rawText " &nbsp; &nbsp; &nbsp; "
-    let dtString  = model.Date.ToString "yyyy-MM-dd"
+    let dtString  = model.Date.ToString ("yyyy-MM-dd", null) // TODO: this should be invariant
     [   div [ _class "pt-center-text" ] [
             br []
             a [ _class  "pt-icon-link"
@@ -327,12 +326,12 @@ let view model viewInfo =
             ]
             if model.CanEmail then
                 spacer
-                if model.Date.DayOfWeek <> DayOfWeek.Sunday then
-                    let rec findSunday (date : DateTime) =
-                        if date.DayOfWeek = DayOfWeek.Sunday then date else findSunday (date.AddDays 1.)
+                if model.Date.DayOfWeek <> IsoDayOfWeek.Sunday then
+                    let rec findSunday (date : LocalDate) =
+                        if date.DayOfWeek = IsoDayOfWeek.Sunday then date else findSunday (date.PlusDays 1)
                     let sunday = findSunday model.Date
                     a [ _class "pt-icon-link"
-                        _href  $"""/prayer-requests/view/{sunday.ToString "yyyy-MM-dd"}"""
+                        _href  $"""/prayer-requests/view/{sunday.ToString ("yyyy-MM-dd", null)}""" // TODO: make invariant
                         _title s["List for Next Sunday"].Value ] [
                         icon "update"; rawText " &nbsp;"; locStr s["List for Next Sunday"]
                     ]
diff --git a/src/PrayerTracker.UI/User.fs b/src/PrayerTracker.UI/User.fs
index 101272d..a6cc7d0 100644
--- a/src/PrayerTracker.UI/User.fs
+++ b/src/PrayerTracker.UI/User.fs
@@ -217,7 +217,10 @@ let maintain (users : User list) ctx viewInfo =
                         ]
                         div [ _class "cell" ] [ str user.Name ]
                         div [ _class "cell" ] [
-                            str (match user.LastSeen with Some dt -> dt.ToString s["MMMM d, yyyy"] | None -> "--")
+                            match user.LastSeen with
+                            | Some dt -> dt.ToString (s["MMMM d, yyyy"].Value, null)
+                            | None -> "--"
+                            |> str
                         ]
                         div [ _class "cell pt-center-text" ] [
                             if user.IsAdmin then strong [] [ locStr s["Yes"] ] else locStr s["No"]
diff --git a/src/PrayerTracker.UI/ViewModels.fs b/src/PrayerTracker.UI/ViewModels.fs
index dce8c95..58dc8b8 100644
--- a/src/PrayerTracker.UI/ViewModels.fs
+++ b/src/PrayerTracker.UI/ViewModels.fs
@@ -116,7 +116,7 @@ type LayoutType =
     | ContentOnly
 
 
-open System
+open NodaTime
 
 /// View model required by the layout template, given as first parameter for all pages in PrayerTracker
 [<NoComparison; NoEquality>]
@@ -134,7 +134,7 @@ type AppViewInfo =
         Version : string
         
         /// The ticks when the request started
-        RequestStart : int64
+        RequestStart : Instant
         
         /// The currently logged on user, if there is one
         User : User option
@@ -151,7 +151,6 @@ type AppViewInfo =
         /// A JavaScript function to run on page load
         OnLoadScript : string option
     }
-    // TODO: add onload script option to this, modify layout to add it 
 
 /// Support for the AppViewInfo type
 module AppViewInfo =
@@ -162,7 +161,7 @@ module AppViewInfo =
             HelpLink     = None
             Messages     = []
             Version      = ""
-            RequestStart = DateTime.Now.Ticks
+            RequestStart = Instant.MinValue
             User         = None
             Group        = None
             Layout       = FullPage
@@ -467,7 +466,7 @@ type EditRequest =
         RequestType : string
         
         /// The date of the request
-        EnteredDate : DateTime option
+        EnteredDate : string option
         
         /// Whether to update the date or not
         SkipDateUpdate : bool option
@@ -724,6 +723,7 @@ module UserLogOn =
         }
 
 
+open System
 open Giraffe.ViewEngine
 
 /// This represents a list of requests
@@ -732,7 +732,7 @@ type RequestList =
         Requests : PrayerRequest list
         
         /// The date for which this list is being generated
-        Date : DateTime
+        Date : LocalDate
         
         /// The small group to which this list belongs
         SmallGroup : SmallGroup
@@ -767,30 +767,31 @@ with
     
     /// Is this request new?
     member this.IsNew (req : PrayerRequest) =
-        (this.Date - req.UpdatedDate).Days <= this.SmallGroup.Preferences.DaysToKeepNew
+        let reqDate = req.UpdatedDate.InZone(SmallGroup.timeZone this.SmallGroup).Date
+        Period.Between(this.Date, reqDate, PeriodUnits.Days).Days <= this.SmallGroup.Preferences.DaysToKeepNew
     
     /// Generate this list as HTML
     member this.AsHtml (s : IStringLocalizer) =
-        let prefs    = this.SmallGroup.Preferences
-        let asOfSize = Math.Round (float prefs.TextFontSize * 0.8, 2)
+        let p        = this.SmallGroup.Preferences
+        let asOfSize = Math.Round (float p.TextFontSize * 0.8, 2)
         [   if this.ShowHeader then
-                div [ _style $"text-align:center;font-family:{prefs.Fonts}" ] [
-                    span [ _style $"font-size:%i{prefs.HeadingFontSize}pt;" ] [
+                div [ _style $"text-align:center;font-family:{p.Fonts}" ] [
+                    span [ _style $"font-size:%i{p.HeadingFontSize}pt;" ] [
                         strong [] [ str s["Prayer Requests"].Value ]
                     ]
                     br []
-                    span [ _style $"font-size:%i{prefs.TextFontSize}pt;" ] [
+                    span [ _style $"font-size:%i{p.TextFontSize}pt;" ] [
                         strong [] [ str this.SmallGroup.Name ]
                         br []
-                        str (this.Date.ToString s["MMMM d, yyyy"].Value)
+                        str (this.Date.ToString (s["MMMM d, yyyy"].Value, null))
                     ]
                 ]
                 br []
             for _, name, reqs in this.RequestsByType s do
                 div [ _style "padding-left:10px;padding-bottom:.5em;" ] [
-                    table [ _style $"font-family:{prefs.Fonts};page-break-inside:avoid;" ] [
+                    table [ _style $"font-family:{p.Fonts};page-break-inside:avoid;" ] [
                         tr [] [
-                            td [ _style $"font-size:%i{prefs.HeadingFontSize}pt;color:{prefs.HeadingColor};padding:3px 0;border-top:solid 3px {prefs.LineColor};border-bottom:solid 3px {prefs.LineColor};font-weight:bold;" ] [
+                            td [ _style $"font-size:%i{p.HeadingFontSize}pt;color:{p.HeadingColor};padding:3px 0;border-top:solid 3px {p.LineColor};border-bottom:solid 3px {p.LineColor};font-weight:bold;" ] [
                                 rawText "&nbsp; &nbsp; "; str name.Value; rawText "&nbsp; &nbsp; "
                             ]
                         ]
@@ -799,7 +800,7 @@ with
                 reqs
                 |> List.map (fun req ->
                     let bullet = if this.IsNew req then "circle" else "disc"
-                    li [ _style $"list-style-type:{bullet};font-family:{prefs.Fonts};font-size:%i{prefs.TextFontSize}pt;padding-bottom:.25em;" ] [
+                    li [ _style $"list-style-type:{bullet};font-family:{p.Fonts};font-size:%i{p.TextFontSize}pt;padding-bottom:.25em;" ] [
                         match req.Requestor with
                         | Some r when r <> "" ->
                             strong [] [ str r ]
@@ -807,14 +808,14 @@ with
                         | Some _ -> ()
                         | None -> ()
                         rawText req.Text
-                        match prefs.AsOfDateDisplay with
+                        match p.AsOfDateDisplay with
                         | NoDisplay -> ()
                         | ShortDate
                         | LongDate ->
                             let dt =
-                                match prefs.AsOfDateDisplay with
-                                | ShortDate -> req.UpdatedDate.ToShortDateString ()
-                                | LongDate -> req.UpdatedDate.ToLongDateString ()
+                                match p.AsOfDateDisplay with
+                                | ShortDate -> req.UpdatedDate.ToString ("d", null)
+                                | LongDate -> req.UpdatedDate.ToString ("D", null)
                                 | _ -> ""
                             i [ _style $"font-size:%.2f{asOfSize}pt" ] [
                                 rawText "&nbsp; ("; str s["as of"].Value; str " "; str dt; rawText ")"
@@ -830,7 +831,7 @@ with
         seq {
             this.SmallGroup.Name
             s["Prayer Requests"].Value
-            this.Date.ToString s["MMMM d, yyyy"].Value
+            this.Date.ToString (s["MMMM d, yyyy"].Value, null)
             " "
             for _, name, reqs in this.RequestsByType s do
                 let dashes = String.replicate (name.Value.Length + 4) "-"
@@ -845,8 +846,8 @@ with
                     | _ ->
                         let dt =
                             match this.SmallGroup.Preferences.AsOfDateDisplay with
-                            | ShortDate -> req.UpdatedDate.ToShortDateString ()
-                            | LongDate -> req.UpdatedDate.ToLongDateString ()
+                            | ShortDate -> req.UpdatedDate.ToString ("d", null)
+                            | LongDate -> req.UpdatedDate.ToString ("D", null)
                             | _ -> ""
                         $"""  ({s["as of"].Value} {dt})"""
                     |> sprintf "  %s %s%s%s" bullet requestor (htmlToPlainText req.Text)
diff --git a/src/PrayerTracker/App.fs b/src/PrayerTracker/App.fs
index 127566b..9013eca 100644
--- a/src/PrayerTracker/App.fs
+++ b/src/PrayerTracker/App.fs
@@ -1,17 +1,17 @@
 namespace PrayerTracker
 
-open System
 open Microsoft.AspNetCore.Http
 
 /// Middleware to add the starting ticks for the request
 type RequestStartMiddleware (next : RequestDelegate) =
     
     member this.InvokeAsync (ctx : HttpContext) = task {
-        ctx.Items[Key.startTime] <- DateTime.Now.Ticks
+        ctx.Items[Key.startTime] <- ctx.Now
         return! next.Invoke ctx
     }
 
 
+open System
 open Microsoft.AspNetCore.Builder
 open Microsoft.AspNetCore.Hosting
 
@@ -71,9 +71,13 @@ module Configure =
         let _ = svc.AddSingleton<IClock> SystemClock.Instance
         
         let config = svc.BuildServiceProvider().GetRequiredService<IConfiguration> ()
+        //NpgsqlConnection.GlobalTypeMapper.
         let _      =
             svc.AddDbContext<AppDbContext> (
-                (fun options -> options.UseNpgsql (config.GetConnectionString "PrayerTracker") |> ignore),
+                (fun options ->
+                    options.UseNpgsql (
+                        config.GetConnectionString "PrayerTracker", fun o -> o.UseNodaTime () |> ignore)
+                    |> ignore),
                 ServiceLifetime.Scoped, ServiceLifetime.Singleton)
         ()
     
diff --git a/src/PrayerTracker/CommonFunctions.fs b/src/PrayerTracker/CommonFunctions.fs
index dcfc314..e02e070 100644
--- a/src/PrayerTracker/CommonFunctions.fs
+++ b/src/PrayerTracker/CommonFunctions.fs
@@ -44,6 +44,7 @@ let appVersion =
 open Giraffe
 open Giraffe.Htmx
 open Microsoft.AspNetCore.Http
+open NodaTime
 open PrayerTracker
 open PrayerTracker.ViewModels
 
@@ -63,7 +64,7 @@ let viewInfo (ctx : HttpContext) =
     { AppViewInfo.fresh with
         Version      = appVersion
         Messages     = msg
-        RequestStart = ctx.Items[Key.startTime] :?> int64
+        RequestStart = ctx.Items[Key.startTime] :?> Instant
         User         = ctx.Session.CurrentUser
         Group        = ctx.Session.CurrentGroup
         Layout       = layout
diff --git a/src/PrayerTracker/Extensions.fs b/src/PrayerTracker/Extensions.fs
index 665d344..cdcfaa1 100644
--- a/src/PrayerTracker/Extensions.fs
+++ b/src/PrayerTracker/Extensions.fs
@@ -1,7 +1,6 @@
 [<AutoOpen>]
 module PrayerTracker.Extensions
 
-open System
 open Microsoft.AspNetCore.Http
 open Microsoft.FSharpLu
 open Newtonsoft.Json
@@ -76,6 +75,9 @@ type HttpContext with
     /// The system clock (via DI)
     member this.Clock = this.GetService<IClock> ()
     
+    /// The current instant
+    member this.Now = this.Clock.GetCurrentInstant ()
+    
     /// The currently logged on small group (sets the value in the session if it is missing)
     member this.CurrentGroup () = task {
         match this.Session.CurrentGroup with
@@ -101,7 +103,7 @@ type HttpContext with
                 match! this.Db.TryUserById userId with
                 | Some user ->
                     // Set last seen for user
-                    this.Db.UpdateEntry { user with LastSeen = Some DateTime.UtcNow }
+                    this.Db.UpdateEntry { user with LastSeen = Some this.Now }
                     let! _ = this.Db.SaveChangesAsync ()
                     this.Session.CurrentUser <- Some user
                     return Some user
diff --git a/src/PrayerTracker/PrayerRequest.fs b/src/PrayerTracker/PrayerRequest.fs
index 1a3bf6b..6f477c2 100644
--- a/src/PrayerTracker/PrayerRequest.fs
+++ b/src/PrayerTracker/PrayerRequest.fs
@@ -20,7 +20,7 @@ let private findRequest (ctx : HttpContext) reqId = task {
 /// Generate a list of requests for the given date
 let private generateRequestList (ctx : HttpContext) date = task {
     let  group    = ctx.Session.CurrentGroup.Value
-    let  listDate = match date with Some d -> d | None -> group.LocalDateNow ctx.Clock
+    let  listDate = match date with Some d -> d | None -> SmallGroup.localDateNow ctx.Clock group
     let! reqs     = ctx.Db.AllRequestsForSmallGroup group ctx.Clock (Some listDate) true 0
     return
         {   Requests   = reqs
@@ -32,29 +32,31 @@ let private generateRequestList (ctx : HttpContext) date = task {
         }
 }
 
-open System
+open NodaTime.Text
 
 /// Parse a string into a date (optionally, of course)
 let private parseListDate (date : string option) =
     match date with
-    | Some dt -> match DateTime.TryParse dt with true, d -> Some d | false, _ -> None
+    | Some dt -> match LocalDatePattern.Iso.Parse dt with it when it.Success -> Some it.Value | _ -> None
     | None -> None
 
+open System
+
 /// GET /prayer-request/[request-id]/edit
 let edit reqId : HttpHandler = requireAccess [ User ] >=> fun next ctx -> task {
     let group     = ctx.Session.CurrentGroup.Value
-    let now       = group.LocalDateNow ctx.Clock
+    let now       = SmallGroup.localDateNow ctx.Clock group
     let requestId = PrayerRequestId reqId
     if requestId.Value = Guid.Empty then
         return!
             { viewInfo ctx with HelpLink = Some Help.editRequest }
-            |> Views.PrayerRequest.edit EditRequest.empty (now.ToString "yyyy-MM-dd") ctx
+            |> Views.PrayerRequest.edit EditRequest.empty (now.ToString ("R", null)) ctx
             |> renderHtml next ctx
     else
         match! findRequest ctx requestId with
         | Ok req ->
             let s = Views.I18N.localizer.Force ()
-            if req.IsExpired now group.Preferences.DaysToExpire then
+            if PrayerRequest.isExpired now group req then
                 { UserMessage.warning with
                     Text        = htmlLocString s["This request is expired."]
                     Description =
@@ -128,7 +130,7 @@ let list groupId : HttpHandler = requireAccess [ AccessLevel.Public ] >=> fun ne
             viewInfo ctx
             |> Views.PrayerRequest.list
                 {   Requests   = reqs
-                    Date       = group.LocalDateNow ctx.Clock
+                    Date       = SmallGroup.localDateNow ctx.Clock group
                     SmallGroup = group
                     ShowHeader = true
                     CanEmail   = Option.isSome ctx.User.UserId
@@ -199,7 +201,7 @@ let restore reqId : HttpHandler = requireAccess [ User ] >=> fun next ctx -> tas
     match! findRequest ctx requestId with
     | Ok req ->
         let s  = Views.I18N.localizer.Force ()
-        ctx.Db.UpdateEntry { req with Expiration = Automatic; UpdatedDate = DateTime.Now }
+        ctx.Db.UpdateEntry { req with Expiration = Automatic; UpdatedDate = ctx.Now }
         let! _ = ctx.Db.SaveChangesAsync ()
         addInfo ctx s["Successfully {0} prayer request", s["Restored"].Value.ToLower ()]
         return! redirectTo false "/prayer-requests" next ctx
@@ -226,10 +228,13 @@ let save : HttpHandler = requireAccess [ User ] >=> validateCsrf >=> fun next ct
                     Expiration  = Expiration.fromCode model.Expiration
                 }
             let group = ctx.Session.CurrentGroup.Value
-            let now   = group.LocalDateNow ctx.Clock
+            let now   = SmallGroup.localDateNow ctx.Clock group
             match model.IsNew with
             | true ->
-                let dt = defaultArg model.EnteredDate now
+                let dt =
+                    (defaultArg (parseListDate model.EnteredDate) now)
+                        .AtStartOfDayInZone(SmallGroup.timeZone group)
+                        .ToInstant()
                 { upd8 with
                     SmallGroupId = group.Id
                     UserId       = ctx.User.UserId.Value
@@ -237,7 +242,7 @@ let save : HttpHandler = requireAccess [ User ] >=> validateCsrf >=> fun next ct
                     UpdatedDate  = dt
                   }
             | false when defaultArg model.SkipDateUpdate false -> upd8
-            | false -> { upd8 with UpdatedDate = now }
+            | false -> { upd8 with UpdatedDate = ctx.Now }
             |> if model.IsNew then ctx.Db.AddEntry else ctx.Db.UpdateEntry
             let! _   = ctx.Db.SaveChangesAsync ()
             let  s   = Views.I18N.localizer.Force ()
diff --git a/src/PrayerTracker/PrayerTracker.fsproj b/src/PrayerTracker/PrayerTracker.fsproj
index 5a01ab7..902c5c7 100644
--- a/src/PrayerTracker/PrayerTracker.fsproj
+++ b/src/PrayerTracker/PrayerTracker.fsproj
@@ -27,8 +27,9 @@
     <PackageReference Include="Giraffe" Version="6.0.0" />
     <PackageReference Include="Giraffe.Htmx" Version="1.8.0" />
     <PackageReference Include="NeoSmart.Caching.Sqlite" Version="6.0.1" />
-    <PackageReference Include="Npgsql.EntityFrameworkCore.PostgreSQL" Version="6.0.5" />
+    <PackageReference Include="Npgsql.EntityFrameworkCore.PostgreSQL" Version="6.0.6" />
     <PackageReference Update="FSharp.Core" Version="6.0.5" />
+    <PackageReference Include="Npgsql.EntityFrameworkCore.PostgreSQL.NodaTime" Version="6.0.6" />
   </ItemGroup>
 
   <ItemGroup>
diff --git a/src/PrayerTracker/SmallGroup.fs b/src/PrayerTracker/SmallGroup.fs
index f504efa..d2d8803 100644
--- a/src/PrayerTracker/SmallGroup.fs
+++ b/src/PrayerTracker/SmallGroup.fs
@@ -261,14 +261,14 @@ let sendAnnouncement : HttpHandler = requireAccess [ User ] >=> validateCsrf >=>
     match! ctx.TryBindFormAsync<Announcement> () with
     | Ok model ->
         let group = ctx.Session.CurrentGroup.Value
-        let prefs = group.Preferences
+        let pref  = group.Preferences
         let usr   = ctx.Session.CurrentUser.Value
-        let now   = group.LocalTimeNow ctx.Clock
+        let now   = SmallGroup.localTimeNow ctx.Clock group
         let s     = Views.I18N.localizer.Force ()
         // Reformat the text to use the class's font stylings
         let requestText = ckEditorToText model.Text
         let htmlText =
-            p [ _style $"font-family:{prefs.Fonts};font-size:%d{prefs.TextFontSize}pt;" ] [ rawText requestText ]
+            p [ _style $"font-family:{pref.Fonts};font-size:%d{pref.TextFontSize}pt;" ] [ rawText requestText ]
             |> renderHtmlNode
         let plainText = (htmlToPlainText >> wordWrap 74) htmlText
         // Send the e-mails
@@ -282,7 +282,7 @@ let sendAnnouncement : HttpHandler = requireAccess [ User ] >=> validateCsrf >=>
                     Recipients    = recipients
                     Group         = group
                     Subject       = s["Announcement for {0} - {1:MMMM d, yyyy} {2}", group.Name, now.Date,
-                                      (now.ToString "h:mm tt").ToLower ()].Value
+                                      (now.ToString ("h:mm tt", null)).ToLower ()].Value
                     HtmlBody      = htmlText
                     PlainTextBody = plainText
                     Strings       = s
@@ -293,14 +293,15 @@ let sendAnnouncement : HttpHandler = requireAccess [ User ] >=> validateCsrf >=>
         | _, None  -> ()
         | _, Some x when not x -> ()
         | _, _ ->
+            let zone = SmallGroup.timeZone group
             { PrayerRequest.empty with
                 Id           = (Guid.NewGuid >> PrayerRequestId) ()
                 SmallGroupId = group.Id
                 UserId       = usr.Id
                 RequestType  = (Option.get >> PrayerRequestType.fromCode) model.RequestType
                 Text         = requestText
-                EnteredDate  = now
-                UpdatedDate  = now
+                EnteredDate  = now.Date.AtStartOfDayInZone(zone).ToInstant()
+                UpdatedDate  = now.InZoneLeniently(zone).ToInstant()
             }
             |> ctx.Db.AddEntry
             let! _ = ctx.Db.SaveChangesAsync ()
diff --git a/src/PrayerTracker/User.fs b/src/PrayerTracker/User.fs
index df9a73c..2c7e3a6 100644
--- a/src/PrayerTracker/User.fs
+++ b/src/PrayerTracker/User.fs
@@ -145,7 +145,7 @@ let doLogOn : HttpHandler = requireAccess [ AccessLevel.Public ] >=> validateCsr
                         AuthenticationProperties (
                             IssuedUtc    = DateTimeOffset.UtcNow,
                             IsPersistent = defaultArg model.RememberMe false))
-                ctx.Db.UpdateEntry { user with LastSeen = Some DateTime.UtcNow }
+                ctx.Db.UpdateEntry { user with LastSeen = Some ctx.Now }
                 let! _ = ctx.Db.SaveChangesAsync ()
                 addHtmlInfo ctx s["Log On Successful • Welcome to {0}", s["PrayerTracker"]]
                 return! redirectTo false (sanitizeUrl model.RedirectUrl "/small-group") next ctx
diff --git a/src/names-to-lower.sql b/src/names-to-lower.sql
index 1e9ec87..a0fcec3 100644
--- a/src/names-to-lower.sql
+++ b/src/names-to-lower.sql
@@ -94,7 +94,7 @@ ALTER TABLE pt."User" RENAME COLUMN "PasswordHash" TO password_hash;
 ALTER TABLE pt."User" RENAME COLUMN "Salt" TO salt;
 ALTER TABLE pt."User" RENAME CONSTRAINT "PK_User" TO pk_pt_user;
 ALTER TABLE pt."User" RENAME TO pt_user;
-ALTER TABLE pt.pt_user ADD COLUMN last_seen timestamp;
+ALTER TABLE pt.pt_user ADD COLUMN last_seen timestamptz;
 
 -- User / Small Group
 ALTER TABLE pt."User_SmallGroup" RENAME COLUMN "UserId" TO user_id;
@@ -105,3 +105,8 @@ ALTER TABLE pt."User_SmallGroup" RENAME CONSTRAINT "FK_User_SmallGroup_SmallGrou
 ALTER TABLE pt."User_SmallGroup" RENAME TO user_small_group;
 
 ALTER INDEX pt."IX_User_SmallGroup_SmallGroupId" RENAME TO ix_user_small_group_small_group_id;
+
+-- #41 - change to timestamptz
+SET TimeZone = 'UTC';
+ALTER TABLE pt.prayer_request ALTER COLUMN entered_date TYPE timestamptz;
+ALTER TABLE pt.prayer_request ALTER COLUMN updated_date TYPE timestamptz;