How much Kalk to drip? Not in ATO

[Ferrell]

Mostly LPS with 3 easy sps recently acquired. Ive been using brs kalk in my ato for 3 months now with varying success. Started slow, 1 tsp/2.5 gallons and adjusted as needed. Make up adjustments on weekend as needed. Problem is varying evaporation rates. Alk recently rose to 10 only dosing 1tsp/gallon. My thought is to utilize a brs dosing pump and dose a set amount of saturated kalkwasser. How do you determine the amount of kalk /day to dose? Ie: X ml of kalk solution per .1 dKh use by coral per day. And is it better to dose on a 24 hr schedule or only when lights off to compensate for ph drop?
Thanks for any advice
75gallon/20gal sump
Ph swing is from 8.0-7.75 daily without kalk (have no way to get outside air except open window on occasion, trying airstones in sump in addition to skimmer. Next step is co2 scrubber as last resort)
Alk 8.9 (today) using only rodi letting it get back down to mid 8s
Cal 450
Mag 1550
Salinity 34

 

[Ranjib]

Theres a max amount that you can dose with kalk as well.
Did you try some other alternative, since kalk is not giving a lot of result ? like Co2 absorbent media in skimmer intake? BRS sells something like that.
If you know a particular time of the day when the ph is dropping, you can also experiment with shutting down skimmer during that time (for few hours).
I wont suggest chasing pH unless you are observing some i'll effect

 

[Ferrell]

Yes I understand kalk is very limited but my demand is not such that a fully saturated kalk wouldn’t keep up. It’s just the varying evap rate where one day the ato puts in a gallon and another it puts in half a gallon. Never sure how much to mix because of the variance. Not great for stability. Alk bounces up and down and so does ph because it’s not putting in same amount a day, so just thinking if I could dose fully saturated kalk I could control the Alk fluctuations and still benefit from the ph buffering.

 

[DharkaronReef]

I'm curious as how other people are dosing Kalk. I currently dose Alk (btw 9-10*dKh) and Magnesium (1260) but I put 2 teaspoons of BRS Kalk Wasser in my ATO bucket for calcium (450ppm).

 

[Randy Holmes-Farley Verified Community Expert]

I'm curious as how other people are dosing Kalk. I currently dose Alk (btw 9-10*dKh) and Magnesium (1260) but I put 2 teaspoons of BRS Kalk Wasser in my ATO bucket for calcium (450ppm).

I used it in my ATO for 20 years, but might switch to a high pH two part or dose the limewater by timed pump if I set up another tank. Either would allow more alkalinity stability with changing weather/evaporation.