04-04-2009, 01:35 AM
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When a fluorescent light bulb package says that it puts out as much light as a 65 watt bulb they are comparing it to an incandescent bulb which has a less efficient light output. when people talk about how many watts they have above their planted tank, it is safe to assume they are talking about the more efficient fluorescent light and they need not relate it to how many watts it would use if they were using incandescent bulbs. So for the purposes of this forum you have 15 watts of light. It is also important to note that many household compact fluorescent bulbs (CFL’s) lack the proper “color” for growing plants. Most Bulbs labeled Full Spectrum or Daylight will do okay, 6,700k is considered ideal.
CO2 will help pretty much any plant but I wouldn’t say it is a necessity, definitely not for hornwort. In a densely planted tank it does make things easier. But it is expensive and for a few small plants not really worth it. If you really want CO2 than look into a DIY system, I used such a system up until recently for a year but have come to resent them because of the dedicated maintenance involved.
If you do not use CO2 than an air stone won’t hurt, it can only help. People commonly hear that air stones drive away CO2, this is true if the concentration of CO2 in the tank water is higher than the concentration in the air surrounding the tank such as in a CO2 injected tank. However when CO2 is not injected into a heavily planted tank, often the concentration of CO2 in the tank is lower than that of the surrounding air and the air stone will help CO2 from the air absorb into the water. Generally your filter will provide the means for the gas exchange of both oxygen and CO2 and serves the purpose of an air stone, and you don’t have to worry about it too much unless you have way too many fish in the tank.