Neutral Regulator and CO2 Controller

[BobD]

Hi. I'm new to CO2 supplementation and so far so good, no fish deaths and plants are growing. I typically do 20% water changes every other week. I fill my containers with cold tap water and treat it with Neutral Regulator then store it at room temperature so it will be ready for the next water change (in two weeks). During each water change I dose the water with Prime just before adding to the tank. I have had great success using this method with previous community and Cichlid aquariums. My question has to do with a newly added CO2 setup with a PH controller on my planted tank. I have the controller set to stop CO2 supplementation when the PH drops to a set point of 6.7. Will the use of Neutral Regulator interfere with that process? Should I use [only] Prime to treat my tap water if the tap water is pretty close to neutral to start with?

[Tech Support LK]

Hi BobD. Welcome to the forum and the wonderful world of CO2 injection ;) Glad to hear you are having success so far.
Neutral Regulator is a phosphate-based buffer that will very preferentially buffer the water at or around 7.0. The impact that Neutral Regulator will have upon CO2 injection is that you pH will drift downward more slowly than if you were not using CO2 injection. Because phosphate-based buffers are more efficient than carbonate-based buffers, you will see more resistance to change in pH from Neutral Regulator. This is the only concern I have. You might consider setting the stopping point a little closer to 7.0 (6.8 or 6.9) for the early testing stages to see how much CO2 needs to be injected in order to drop the pH to 6.7. If the Neutral Regulator is in abundance enough it may do a very good job of not allowing your pH to drift down that far causing continuous injection of CO2. Make sense?
If you have a neutral pH coming out of the tap and a decent KH (3 or so), you might consider discontinuing the use of Neutral Regulator. If you do this, you will likely want to invest in some sort of carbonate-based buffer to ensure that your water contains a consistent amount of KH. Hope this helps!

[BobD]

Ah! Just as I suspected! Thanks for the quick reply. I'm thinking, for now, I'll stick to the regimen I've been using while configuring the controller for a pH set point of 6.8 (as you suggested). I'm hoping the effects of the Neutral Regulator will establish a solid baseline making the pH level more predictable thus easier to control via CO2 injection. Thanks again!

[Tech Support DD]

You're very welcome :-) Your plan sounds good; let us know if you ever have any other questions.