Effluent dKH Tuning

[Grizzy56]

I know this topic is beaten to death...but what's one more thread! I'm just looking for verification and/or suggestions. I've got a Red Sea Reefer 625 xxl and recently setup a CARX (Reef Octopus CR-140 DC) with Caribsea ARM extra course media, a Carbondoser regulator and a Kamoer FX-STP pulling through the reactor. I've been at it for about two weeks and have made only incremental adjustments every 48 hours to either the bubbles per second, flow pressure, or pH with the reactor. I've only adjusted one of those variables at a time and logged the adjustments and effects of both the effluent and tank dKH. The reactor pH is controlled by an Apex system and I currently have my CO2 high and low limits set to 6.54 and 6.52 and dosing at 1 bubble per second at a low rate of 30mL/min with a CO2 flow pressure of 12psi. My issue is that my effluent is not raising above 10.5 (max) not matter what I do. At the moment my tank is only a moderate demand, so any deviance from my ideal parameters is easily handled by hand dosing (every 48 hours) but I'd like to figure this out a little better. I've tried dosing more mL/min but that obviously decreases the dKH within the reactor and doesn't balance out the demand. It's tempting but I don't want to lower my pH inside the reactor any more than it is unless absolutely necessary but that doesn't seem right to me. I'm thinking of taking the pH control off and trying to balance the effluent dKH using bubble size and bubble count. Any thoughts or suggestions?

 

[TX_Punisher]

Why don’t you want to lower reactor ph? Are you afraid of lowering tank ph by doing so?

I just checked mine and I’m at about 6.3 (reactor ph).

 

[HuduVudu]

The reactor pH is controlled by an Apex system

This is a very risky thing to do. This is a closed system and though it seems easy it has some serious draw backs. I would not suggest using a closed loop here. Honestly using a probe here is less than ideal.

My issue is that my effluent is not raising above 10.5 (max) not matter what I do.

You need to either lower your flow rate or raise your bubble count. Since you are running 30ml/min I would suggest lowering this first. This does seem pretty high.

At the moment my tank is only a moderate demand

What do you have in the tank as far as consumers?

so any deviance from my ideal parameters is easily handled by hand dosing (every 48 hours)

I would not dose. That will bring a whole new set of problems and could likely introduce a feedback loop.

Stability is more important than exact numbers. You need to get the reactor stable first, and after you have gotten it where you want, then you can dose to get what you want. As an alternative I would suggest water changes to get where you want. You will need to likely do that anyway if you have been dosing out of ratio.