Lowering Alk using sodium bisulfate

[Randy Holmes-Farley Verified Community Expert]

So 1.2 grams per 10 Liters, drops alkalinity by 2.8 dKH.

If you do not have a scale, we can roughly estimate how much is in a teaspoon:

(That’s from your older post I just want to make sure I’m doing this correctly before I start)

So I’ll be adding bisulfate to a 5 gallon (approx 18.927L) two level teaspoons should drop the alk in the bucket by 5.6 (2.8 x2)
Last time I tested my bucket salt mix was around 7.8 which means my 5 gallon new salt water
Mix should be around 2.2dKH. If all my math is correct will adding 2.2dKh negatively affect 42 gallons of tank water at 10.9?
Will the drop be too sudden too fast or is this considered minimal?

No. From that thread:

1 level dry teaspoon of sodium bisulfate added per 100 L of tank water will drop the alkalinity by about 1.7 dKH.

So 2 teaspoons will drop alk by 17 dKH 20 L.

 

[Randy Holmes-Farley Verified Community Expert]

I was under the impression that rock would leach/produce alk only under a certain ph.

Yes, but the pH deep down in it is lower from degradation of organics producing CO2, as well as in the gi tracts of organisms. Long term reefers sometimes have to replenish sand from dissolution. Larry Jackson said 25 years ago that he periodically had to do this.

 

[Miami Reef]

Knowing the cause often does not provide a solution. Folks with low demand tanks do see alk rises and it is likely from sand and rock dissolution.

Well, if that was the cause, then the solution is pretty simple: add more corals. ;)

Nevertheless, you do have a point about reefing having many “temporary solutions”. I was assuming that OP was adding something to the tank that was adding alkalinity, that’s why I was adamant about finding the cause, but I definitely learned something new.

Thanks! :)


Now the next experiment is seeing how long it takes for alkalinity to go back up once it was lowered. That would be interesting.

 

[Randy Holmes-Farley Verified Community Expert]

Well, if that was the cause, then the solution is pretty simple: add more corals. ;)

Nevertheless, you do have a point about reefing having many “temporary solutions”. I was assuming that OP was adding something to the tank that was adding alkalinity, that’s why I was adamant about finding the cause, but I definitely learned something new.

Thanks! :)


Now the next experiment is seeing how long it takes for alkalinity to go back up once it was lowered. That would be interesting.

Yes, boosting demand would solve the issue that these folks have.