PH considerations when dosing Kalk - ATO or seperate?

[ultimatemj]

Hello,

I've been dosing kalk via my ATO pushing through an Avast kalk stirrer, and have an APEX setup with code to turn it off when PH goes above 8.4.

I'm noticing the traditional photosynthetic period PH swings....just larger than I expected.

Overnight it consistently goes down to 8.05, with the occasional bump up from some top off. But during the day it consistently hits 8.4 and goes on/off on/off to get the top off level.

Sump level and salinity-wise, I'm fine with this, but does the size of the PH swing matter? Should I be considering separating the functions to maintain more consistent PH around the clock?

If I leave them together, what do you think about 8.4 as my cut off? Would you consider a different number for the cut off (higher or lower)?

Thanks!

 

[Randy Holmes-Farley Verified Community Expert]

You could raise the cutoff to 8.55, but that might not matter except for the on/off cycling of your dosing pumps. My tnak seemed to run fine at pH 8.35 to 8.55 for years using limewater in my ATO (then I got new storm windows and the pH declined )

I do not think the swing is very important in general, as long as the extremes do not go outside the norm.

Dosing more at night would bring up the low pH end and stabilize pH, but would tend to "destabilize" alkalinity, and I'm not sure which is more of a concern. It may depend on the type of tank.