Help Dialing In Kalk Dosing

[Evan West]

So I have a 20g mixed reef tanks with a fair amount of coral in it. I am trying to dial in my dose for Kalk, currently I am up to 145ml dosed in a 24hr period of limewater at a concentration of 2 teaspoons per gallon. The Kalk is just mixed and then left in a tightly sealed jug, I don’t use a stirrer or anything. It was at 120ml per gallon but I was away for 4 days and the alk still dropped from 7.0 to 5.6 so I bumped it up to the 145ml last night after a WC. Is this level of consumption normal?

 

[Randy Holmes-Farley Verified Community Expert]

It's a very small dose. That 145 mL is adding on the order of 0.25 dKH to the alkalinity in a 20 gallon system.

Most people replace more or all of the evaporated water, but whatever amounts maintains alkalinity is the right dose.

 

[Evan West]

It's a very small dose. That 145 mL is adding on the order of 0.25 dKH to the alkalinity in a 20 gallon system.

Most people replace more or all of the evaporated water, but whatever amounts maintains alkalinity is the right dose.

Thanks! Just wasnt sure how much was a lot for Kalk!

 

[Evan West]

It's a very small dose. That 145 mL is adding on the order of 0.25 dKH to the alkalinity in a 20 gallon system.

Most people replace more or all of the evaporated water, but whatever amounts maintains alkalinity is the right dose.

So correct me if im wrong here but if im adding+.25 dKH a day and still dropped -1.4 dKH then my total drop over 4 days is around -2.4 dKH so that comes out to .6 dKH per day, unless the math doesn’t work linearly like this?

Assuming that the above is correct then if 145ml equates to .25 dKH per day then to hit .6 dKH per day I would need around 340ml per day?

 

[Randy Holmes-Farley Verified Community Expert]

It's not exactly linear because the alk drops more slowly as the actual alk declines, almost stopping below 6 dKH. But its a place to start.

Here's a calculator for figuring limewater doses:

http://reef.diesyst.com/chemcalc/chem_calc3.html

It's better to underestimate and work up than overshoot alk too high.