The Carbo-Plus is a system that generates CO2 through electrolysis. You drop the electrode block in the tank, and it produces CO2
from the calcium carbonate in the water. The amount of CO2 generated is controlled by a dial on a box that stays outside the tank. It really does work...but it is worth it?
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It's safe. No need to worry about yeast being siphoned into the tank, bottles tipping over or exploding, or too much CO2 getting into the tank. If you're the type who isn't comfortable with having a tank full of compressed gas in the house, this might be for you. It's convenient, if you live somewhere where it's not easy to get a CO2 refill. With the Carbo-Plus, you can mail-order the replacement blocks. |
It's messy. The reaction causes calcium to precipitate out of the water as whitish-brown flakes. This is very unattractive, and there's not much you can do about it. It's not very powerful. It worked okay on my 75 gallon tank when I had only 130 watts of light over it. But once I upgraded to 240 watts, the plants used up so much CO2 the Carbo-Plus couldn't keep up, even at the highest setting. It's best suited for smaller tanks. It can cause pH crashes. Since the reaction uses up the carbonate (KH) in the water in order to produce CO2, the pH drops. The manufacturer warns that 30% weekly water changes are nececessary to avoid pH problems. IME, even that isn't enough. When I got a pressurized system for my 75 gallon tank, I put the Carbo-Plus on my 29 gallon tank. It worked fine on a tank that size. I only had to set it at 20% or 30% to get enough CO2 in the tank. However, even with 30% weekly water changes, it's hard to maintain the KH and pH. The KH was less than 1 degree, the pH 6.6, last time I measured it. (Before the Carbo-Plus went in, KH was 3 and pH was 7.4.) I didn't have this problem in the 75 gallon tank, and I think it's because there's a substrate of Onyx Sand in that tank. (Onyx buffers the water.) For the reasons given above, it works better in hard water than in soft. Some people complain that it doesn't work at all in soft water. You can only use it in one tank at a time. If you want to add CO2 to another tank, you have to buy another complete Carbo-Plus system. With compressed CO2, you can hook up several tanks to one CO2 cylinder.
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