Couple comments:I can tell you what I'm doing. As a newbie to this sport, take it for what it's worth.
- test your Kh, and determine if that number is where your tank will likely run
- refer this chart to find your desired pH to get the CO2 level where you want it (30 ppm is common)
- set your controller to turn on CO2 when it's .5 pH higher than your goal, and to turn off when it's .5 below your target pH
Thank you. I fixed a typo in my post. I run my pH from 6.8-6.9.Couple comments:
- You do not want to have that big of a range in your pH set point; if, for example, you have a target pH of 6.5 at a kH of 3 (29 ppm, which is reasonable), letting your pH get to 6.0 before turning it off and not turning it on until it gets to 7.0 is a swing from 9 ppm to 90 ppm of CO2. This is not good. Beyond the fact that 90 ppm is going to be very hard on your fish, large swings like that are an invitation to algae problems.
- Using the kH method to calculate CO2 concentration by pH is only accurate if sodium bicarbonate (I think) is the only source of carbonate hardness, but most of the time there are other sources, so using this method will usually result in a little bit less CO2 concentration than you think you are getting.
In addition to using the kH method, I also have a drop checker and check that I am only dropping the pH by about 1.0 (from no CO2 to target point) – between the three methods, I am reasonably sure that I’m pretty close to 30 ppm. Also, my pH controller is set to turn on at 6.6 and off 6.65 - not that I'm saying that's the target you should use, but I would keep the range from on to off closer to the 0.05 to 0.1 range.
I think many algae problems we see in high tech tanks around here are CO2 related. Usually people thinking they have *enough* because their drop checker says so in the absence of any further investigation. Many are experiencing big fluctuations in CO2 concentration and are not exceeding plant uptake at times.There's nothing to my knowledge in co2 itself that prevents algae. It simply drives uptake so the plant mass has to be there to do that. If you had a sparsely planted tank how much of an affect can co2 have on algae prevention. If you put co2 on a fish only tank it's not going to help at all with algae.