When I first started with planted tanks, I was considering using a ph controller. But after doing a little bit of research, I realized it was a huge waste of money and hardly none of the serious planted tank folks even use these. Here's why:
- Injecting co2 lowers your ph, yes. But co2-induced ph swings do not affect your fish in any way shape or form. Why? Because your not changing the TDS of the water (total dissolved solids). If the TDS were to change rapidly, then you could shock your fish. But not with co2 because TDS is not affected.
- By injecting co2 based on a pre-set ph level, you're never really sure what your co2 levels are. Sure, you could look at the ph based on the monitor, then take a kh reading and see what your co2 levels based on the kh/ph chart, but this is not accurate, and is an archaic method for measuring co2. Why? A number of factors can skew your KH readings; driftwood, rocks, plants, substrate, decaying matter, etc. Relying on your ph/kh to measure your co2 levels will never give you an accurate reading, unless you had a completely bare tank. This is why we use drop checkers, read below:
- By using a drop checker with lab-certified 4dkh solution you can know with reasonable accuracy what your co2 levels are. How? Add 4dkh solution to the drop checker, then add a couple of drops of ph reagent from your standard ph test kit, it will turn blue. After injecting co2 for a couple hours you'll see it starts to turn green, these are optimal co2 levels. Why? Well our KH value is set and known at 4dkh, that will not change. The color will change based on the co2 in the water outgassing into the drop checker. Remember how we used ph drops from your ph test kit? Compare the color in the drop checker to that of your test kit color card. See the green color, 6.6? Now look at the kh/ph chart. A kh of 4 and a ph of 6.6 gives you 30ppm of co2, which is considered optimal. I myself like to push it a little higher and keep my drop checker yellow:
- With a ph controller however, let's say you set it to maintain a ph of 6.6. Ok, but what are your co2 levels? You could use a drop checker, and see perhaps may see that at a ph of 6.6, your drop checker is still showing a blue-green color. You want green to lime green, so you reduce the ph in your controller to 6.0. Now you get deep green. So you reduce the ph again. See what I'm saying? It's an unecessary expense and complicates things more. And like I said, you can keep lowering the ph, but it's not going to harm your fish....TDS!!!! With a drop checker, good needle valve, and a timer, I can have my co2 levels fine-tuned within a few hours of setting the tank up.
- Now, as you can see, it's much easier and cheaper to simply control your co2 with a timer and a drop checker. This is what most folks do. My co2 goes off before the lights go off, so I'm never injecting it at night. By using a ph controller, you will be injecting co2 24hrs a day, and we all know plants don't use co2 when the lights are out, they give OFF co2. Some folks will then put their controller on a timer to stop when the lights go out. Why? I have no idea. Point is, a ph controller is essentially worthless and you can do w/o IMO. Never used one and never will.
Ok, enough rambling. Boy, did I make any sense at all?
