Ph rise with alkalinity drop?

[Ooh fiddlesticks]

Yesterday I tested my water, I’m going to list the Paramus I think are important, let me know if anyone wants to see other parameters.
Alk- 8.4
Cal- 440
Ph- 7.6
Salinity 1.026
Mag 1250

I brought the mag to 1350,
Then added 1tbsp of kalk to my ato with 5 gallons in it, shook it up, put the pump back in and headed to the store for some fish.
I ended up getting a birds nest and some sort of encrusting monti the guy threw in for free and picked up a few other things.

I got home from work today and tested.
Alk-8.1
Cal-450
Ph- 8.2

What process would cause my ph to rise and my alkalinity to drop?
Testes were taken with Red Sea kits, I tested alk and cal 3 times to refamiliarize myself with testing,
I tested both twice Tonight because it doesn’t make sense to me.

The hydroxide portion of kalk bonds with co2 to make bicarbonate and raise ph, I would have expected alk to rise proportional to the ph rise.

 

[Ooh fiddlesticks]

Probably testing error I guess. I’ll check again tomorrow

 

[Randy Holmes-Farley Verified Community Expert]

Adding kalk can boost pH, and higher pH can increase alk demand.

 

[Ooh fiddlesticks]

Adding kalk can boost pH, and higher pH can increase alk demand.

But I only have 2 frags and some coralline, I shouldn’t have much of an alk demand at this point unless there’s some other process I’m not familiar with.
I suppose it’s possible that the things I desire are not the only things using alkalinity up.

 

[Randy Holmes-Farley Verified Community Expert]

But I only have 2 frags and some coralline, I shouldn’t have much of an alk demand at this point unless there’s some other process I’m not familiar with.
I suppose it’s possible that the things I desire are not the only things using alkalinity up.

Many things consume alk, including simple precipitation. If you take an empty tank with some sand and rock, and keep adding kalk, pH will rise and alk may not.

 

[Dr_Orpheus]

But I only have 2 frags and some coralline, I shouldn’t have much of an alk demand at this point unless there’s some other process I’m not familiar with.
I suppose it’s possible that the things I desire are not the only things using alkalinity up.

I don't want to say this is the case, but never underestimate the power of coralline algae starting to take off, as well as other critters. My last issue in my 13g was coralline algae starting to go through a growth spurt after the tank started coming together alongside a sudden explosion of hundreds of Rissoid and Collonista snails, and preoccupied me didn't test for 3 weeks. I only took a look because it seemed like something was slightly off, I might have had maybe 3-4 square inches of hard corals in the entire tank, mostly Psammocora and chalice corals, which also grew during most of this time. With dosing the amount I thought I was supposed to do in that time alongside water changes, KH went from 8.5-9 to 5, calcium from 440-350. Surprisingly, only one coral was a little peeved, but it was then I noticed all the tiny snails alongside the coralline growth. I've never had this bad of a drop before in my years of doing this, but this tank had all the goods to allow it to happen.

To make sure my calcium remains more stable and my Nero 3 doesn't go through spurts of getting clogged by baby snails, I have added a couple extra hermits and a gold coral banded shrimp to hopefully eat some of, or eventually all of those small snails. I don't want all my calcium going to them! Hah

 

[Ooh fiddlesticks]

Many things consume alk, including simple precipitation. If you take an empty tank with some sand and rock, and keep adding kalk, pH will rise and alk may not.

This is true, I’ll be testing daily to watch a trend, it may balance out, go up or down. We’ll see. Thankfully all tests are cheap and easy.