View Full Version : Ca/Alk Question, need help

07/11/2017, 05:36 PM
I have been dosing Ca manually (liquid) and adding Baking Soda to my ATO. Ca has been slightly up and down but the more or less 400-450

Alk has been pretty solid at 10. Ran this way for about 4 months.. I tried to start adding Kalk to my ATO instead of doing the above hoping the Kalk would keep the ALk and Ca steady.

It worked for the Ca, but the Alk dropped like a rock..went from 10 to 7..ugh..I\

I am adding 2 Tablespoons per gallon...and I'm going through about 1 gallon a day in evaporation..Do I need to add more Kalk to the solution? Oh.. and Mg hasn't really changed too much.. 1300ish most times I test

07/11/2017, 06:19 PM
Only about 2 tsp will dissolve per gallon. That's one of the limitations of Kalk: it is very dilute. You could try adding 45 ml of vinegar per gallon to increase the concentration, but be sure to watch for bacterial slimes and the like. The vinegar can cause blooms of various microbes. I suspect you'll need to use two-part. Many tanks consume more calcium and alkalinity than Kalk can provide. A fan might increase the evaporation rate, but it might be too effective. I'd try that experiment on a day when I could watch the pH in the system.

The reason calcium seems steady is that a drop of 2.8 dKH only results in 20 ppm reduction in calcium, which is near the limits of most hobbyist test kits.

07/11/2017, 06:48 PM
Thanks for the reply!!
wait wait.. arrrgh made a mistake in my typing.. sorry!!

I am using 2 Tbsps per 3.5 gallons..does that change your response ?

I used this to help try to hone in on what was needed..

07/11/2017, 08:03 PM
That's almost saturation. You could add a bit more Kalk and it would dissolve without vinegar, but the difference would be minimal. This article covers the use of vinegar (and Kalk in general):


I still suspect that you're going to need to use two-part.

07/11/2017, 08:39 PM
Thank you very much for the feedback..never would I thought I would ever have an aquarium where talk would not keep up .. jeez..2 part here we come I guess!

07/12/2017, 12:43 PM
Here is a useful tool for calculating the contribution Kalk makes.