Removing pH controller?


Junior Poster
Dec 18, 2007
Syracuse, NY
Others here have suggested that using a pH controller is not advisable because of the resulting CO2 fluctuations. I recently added a drop checker and keep it at a steady green with automated CO2 injection using a PinPoint controller (pH ~6.4-6.5). I also modified my AM 1000 reactor with a venturi loop to increase misting and removed about 1/2 of the bioballs to increase flow. The response has been great so far, but I'm wondering if the on/off cycles caused by the controller are somehow limiting. The misting, obviously, only occurs when the CO2 is on.

Until now, I had assumed that the CO2 fluctuations were OK as long as there was always "enough". Does variation in CO2, even if it's, for example, a cycling swing from 30-35ppm or so have a negative/limiting impact on plants? I'd like to have a steady misting, regardless, so am considering removing the controller from my setup and relying instead on manual control. I'm concerned, however, about removing this level of automation...without constant attention how can I be certain that I don't end up with too much CO2 and a tank full of floaters?!

Any thoughts, pointers and/or links to further reading are greatly appreciated!


Plant Guru Team
Lifetime Member
Sep 23, 2007
South Florida

I also use a controller and like that it turns off the c02 at a certain level. If working properly there won't be a huge drop in c02 levels. Also convserves c02.

I turn off my c02 and lights for about 90 minutes each day in the afternoon (3-6) to allow the fish some natural daylight and also have the lights on later at night when I am home. My DC color doesn't change much and the plants all pearl within minutes of lights back on even with this 3 hours rest period.

That being said, it may be optimal to have continuous c02 for the plants, as long as the fish are not affected adversely.

You can remove the ph controller once you are happy with the c02 flow/content/DC color/ etc. I know other folks have done it.

However, IMO you should at least hook it to the light timer so as to TURN OFF the c02 when the lights are off. There is no need for c02 at night as the plants don't assimilate c02 (no photosynthesis) and give off c02 as well as the fish. Keeping it on 24/7 is not necessary.

Also, the controller is a quick way to double check that your c02 is where you had it. Keep in mind that the DC takes several hours to equate with the tank water and show a color. Ph probe is dynamic and real time. Leaks, non-precision needle valves, etc all can affect the c02 flow so bad things can happen quickly.

C02 and ph related swings are normal in c02/planted tanks, as most of us turn off the co2 at some point. Since my DC is blue in the am (ph probe shows 7.5) and green several hours later (probe shows 6.3), and the tank has no issues, algae, etc, I feel that these swings are okay. I have to think that others running c02 also have swings.

If I am wrong in any of this, I know others will jump in to help :)

I did the AM 1000 mod as well for my 180 and it also worked well :)

Hope this helps.

Start browsing the threads, as these topics come up all the time.........

Happy reading.


Lifetime Charter Member
Lifetime Member
Jul 27, 2007
what is AM 1000 mod? i have one of thees unit am gone use with my canister filter.

Tom Barr

Staff member
Jan 23, 2005
If you have an AM 1000 reactor, then open the air bleed valve on the top of the reactor. Attach some 3/16" airline to this and place the other end inside the suction side of the pump driving water through the reactor.

You can control the rate of purge by adjusting the bleed valve also.

You can also open up the reactor and on the inside, add some rigid airline tubing to set the intake lower down, say 3 cm deep, before the purge starts to work.

Tom Barr