How can my alk be this high?

Muffin87 · May 19, 2023

I've set up a tank, which at the moment only has a couple of clowns and cheato luckily.
It's a barebottom with Aquaforest rock. Since it's a new tank with no corals, I've not checked Alk often, only NO3 and PO4.

I use RO/DI, which I check regularly, and my instant ocean mixes to 11 dKH, but, I have no idea why, this tank has 14 to 15 dKH.
I've checked the salinity with a refractometer and the Dupla precision hydrometer. It's 35 ppt.

I've double checked my hanna checker against a standard solution. The hanna checker only measures 5% higher than the standard solution (which is admittedly a bit old, even if well preserved).

Where am I getting this crazy Alk from and is there a calculator somewhere to lower it?

benscorals · May 19, 2023

Are you sure the test kit is accurate 11dkh is high for a salt mix

TokenReefer · May 19, 2023

benscorals said:
Are you sure the test kit is accurate 11dkh is high for a salt mix

Thread 'The Ultimate Salt Test' https://www.reef2reef.com/threads/the-ultimate-salt-test.949805/

archercorals · May 19, 2023

Is there anything at all you are adding or supplementing

benscorals · May 19, 2023

I had the same issue in my tank from using dry rock and the alk was always crazy high at 14 and I had to do a lot of water changes with low DKh salt

Muffin87 · May 20, 2023

archercorals said:
Is there anything at all you are adding or supplementing

I’m adding chaeto gro for the chaeto, at the standard dose. So it shouldn’t contain much Alk at all.

Muffin87 · May 20, 2023

benscorals said:
I had the same issue in my tank from using dry rock and the alk was always crazy high at 14 and I had to do a lot of water changes with low DKh salt

The thing is when I tasted Alk a couple of months ago it was 11 dkh.

APlusAquatics · May 20, 2023

Maybe this is playing into it?

Relationship between nitrate and alk

Muffin87 · May 20, 2023

APlusAquatics said:
Maybe this is playing into it?

Relationship between nitrate and alk

Interesting, but this process only restores Alk to some previous level, it doesn’t boost Alk per se. You can’t get Alk higher than your salt mix by nitrate consumption. So it doesn’t explain my situation.

At least that’s my understanding from reading about this.

very useful to keep in mind tho, thanks a lot for the info!

APlusAquatics · May 20, 2023

Muffin87 said:
Interesting, but this process only restores Alk to some previous level, it doesn’t boost Alk per se. You can’t get Alk higher than your salt mix by nitrate consumption. So it doesn’t explain my situation.

At least that’s my understanding from reading about this.

very useful to keep in mind tho, thanks a lot for the info!

No problem, It's one of the things I had issues with at one point a couple years ago. I was stumped just like you are haha!

Were you dosing alk at any point before seeing the increase?

Randy Holmes-Farley · May 20, 2023

Muffin87 said:
Interesting, but this process only restores Alk to some previous level, it doesn’t boost Alk per se. You can’t get Alk higher than your salt mix by nitrate consumption. So it doesn’t explain my situation.

At least that’s my understanding from reading about this.

very useful to keep in mind tho, thanks a lot for the info!

Did you do anything to maintain alk in the past?

Muffin87 · May 20, 2023

Randy Holmes-Farley said:
Did you do anything to maintain alk in the past?

nothing at all

Randy Holmes-Farley · May 21, 2023

Then assuming it’s not coming from your top off water, and isn’t test error, it may be from slow dissolution of rock and sand coupled with low demand to offset it.

FactoryKTMmotocross46 · May 21, 2023

Definately get a second (different) test kit like salifert or even api. Just an fyi... my reagent was almost expired and I was getting low readings. I kept dosing to raise.. long story short, it was the reagent. Not saying this is your issue but I would definitely eliminate it as a possibility first. Your io batch might have a high alk.

Nano_Man · May 21, 2023

I have had these readings and I also use instant ocean I was sat at 15 that high it was melting zoas. Water through my rodi then test after mixed if still high I use a small amount of acid buffer to reduce to what level I want . This is a ongoing issue at the moment but once my instant ocean is finished iam changing to another salt with the closest to the levels I need . I could be wrong but io kh when mixed is 11?. Good advice from all above and Randy knowledge when I read his info it doesn’t go in I have to read it 2or 3 times lol . But his various recipes are spot on and work good.