Does these Alk figures make sense?

[BAMatter]

I’ve been dosing Kalkwasser at night, about 63ml every 30 mins in my system which I estimate to be about 85-90 total gallons. This runs 24 times between 9:00pm and 9:00am. I estimate that to be my daily Alk consumption for 24 hours.

I’m trying to figure out Alk consumption during the day and will supplement the Kalk with 2 part from 9:00am to 9:00pm.

I tested Alk around 6:00pm last night and it was 10dkh. I tested again this morning at 7:15am with the plan of testing tonight to see what the dkh drop was during the day. Alk tested at 9.9dkh. I use a Hannah checker for these tests.

I’m confused as to how I’m getting that Alk reading essentially the same at 6:00pm and 7:15am. I’m translating it as my entire Alk consumption is taking place at night… am I way off base here with this thought process?

 

[Timfish]

I'd suggest doing 3-4 tests 5 - 10 minutes apart from the same location to see how much your tester may vary. Or better yet make an alklinity standard. When I got my hanna alklinity tester I compared it to a friend's hanna using both sets of reagen in both testers. 4 tests from the same place in the aquarium gave 4 different results that varied by .9 dKH. Personally I prefer API's alkalinity test, it's more than accurate enough (researchers use the meq/l method which is about half as sensitive as dKH method) and easier to use and cheaper.