Kalk and Alk

[jml1149]

Hello!

I dose Kalk via peristalic pump, seperate from my ATK unit. After a time away, I returned and found my Alk was at 6.7, measure using two different Salifert Alk test kits. Tank looked like heck. I began upping my Kalk dose, and have done so quite substantially, as below. Yet my Alk remains at 7.8, as measured by two test kits again.

I use an Avast Kalk stirrer with a pH probe, and keep the pH of the contents of the stirrer greater than 12.4.

I'm well within the daily requirement of FW topoff, so I can continue to increase the Kalk dose. However, I'm concerned there's something going on that I don't understand?

Note at the same time my Kalk dose increases, my tank pH range has changed from 7.8 - 8.0 to 8.1 - 8.3. Is it possible this increase in pH is also increasing Alk demand?

For the Salifert results, I record when the solution changes from blue to grey, and then again from grey to pinkish. My goal is to get the mid point of that to 8.0.

Thanks!!!

 

[jml1149]

Note the pump is a BRS 40 mL/min pump and I have found it to be very accurate.

 

[Randy Holmes-Farley Verified Community Expert]

FWIW, alkalinity at 6.7 dKH should not generally be a problem. It about matches where most corals naturally come from in the ocean.

Demand for calcium and alkalinity rises very fast as you raise the alk (and pH).

What is the aquarium water volume (to calculate the alkalinity delivered per day in dKH or meq/L)?