Stirring Top Off water
 

Is it necessary to stir 20 gallons of top off water? I've added Reef Builder (baking soda) to raise my alkalinity. Noticing the powder settled at bottom I put a power head connected to a timer in the top off bucket to run every other hour. Will this cause any issues? My dosing bucket with KALK isn't doing it anymore. After adding the reef builder in top off DKH raised from 6 to 10 and after several days PH dropped from 8.50 stabilized at 8.35 by mid day.

i would run the pump for 2-4 hrs after putting chemicals in and thats about it. after its mixed dont need to have any movement in it.

It is smart to oxygenate it and blow off the excess CO2 (which is what happened when your pH dropped a bit). I always keep it moving.

If you keep water moving with a pump eventually heat from pump will cause the alk to precipitate leaving residue and dropping alk and pH levels anyways.
I wouldn't use any source that puts out heat like a pump, if u really want to keep pH up use a airstone.

I would not worry about the pH of top off water. Unless you're toping off with muriatic acid.

FWIW I used to use Reef Builder in my top off water for years and never mixed it for more than a couple hours or so. No problem.

I would mix it in thoroughly and leave it still or preferably dose it separate from top off , since top off involves moving water and variability in dosing rates tied to variable evaporation rates.. Continuous agitation will cause more gas exchange with the air which could easily introduce CO2

Alkalinity is not a chemical, what do you mean it precipitates?

I think its safe to assume he meant CaCO3. But clarification is a good thing.

I also agree with TMZ with not dosing via top off water.

Calcium carbonate/CaCo3 would precipitate and heat will reduce the amount of calcium and carbonate that can remain in solution. However, the OP isn't dosing any calcium/Ca to the top off reservoir.
There are solubility limits for carbonate / bicarbonate aside from precipitation. I suspect the powder at the bottom is undissolved carbonate /bicarbonate.

Alkalinity is not a single thing it is a measure of things that neutralize acid including: CO3 ,CHO3( carbonate/ bicarbonate), PO4/HPO4, borate ,oxide ,silicone,magenesium hydroxide. In seawater and aquarium salt water roughly 96.5% of the alkainity is carbonate/bicarbonate a measure of which is typically used as a measure of alkalinity.

Thank you Jason, and tmz for detailed elaboration.

you are welcome