Early Christmas gift
 

So my wife just got me a 20 gallon standard tetra tank kit. Came with full hood with light and a filter. She also got me 1 amazon sword, some dwarf hairgrass, and some crypts. I threw it all together just now and I think it looks wonderful. However, I need a light recommendation. It is one of the crazy dual lamp socket hoods rather than a straight fluorescent bar type. It came with 2 15w incandescent bulbs that I have currently installed in it. However, I am looking for which lights I should be looking for to go with low tech planted. I am not going to do any crazy Co2 setups or anything but I would like to have fluorescents cause the light looks better to me. Any recommendations would be great thanks.

GE 15w Daylight CFL bulbs will fit perfect and have a 6500k spectrum.

Thanks for the suggestion. I stopped by the closest walmart and they had 10s and 20s so I bought a pack of the 10s. Said they are comparable to 40w incandescent so that would me I am at 2wpg right?

Watts is not a usable guide, as I'll explain in a moment. To your 10w CFL (compact fluorescent) bulbs, I would get higher wattage. I have two 10w GE daylight CFLs over my 10g and 20g tanks, and they are fine. I have a 29g tank, and I doubt two 10w will provide sufficient intensity. I know there are 13w CFLs, but I would suggest the next higher wattage, whatever it might be.

Now to explain watts. This is simply the measurement used for the amount of energy (= electricity) needed by a bulb/tube to produce the light it emits. It has no direct relation to intensity, except when comparing identical types. As in the above, a 13w GE daylight is obviously more intense (brighter) than a 10w. But that is as far as comparisons can go.

The light needed over a given aquarium varies due to depth, length, width. The type of plants impacts this, since some will do well on less light than others. There is no guide such as the sometimes-seen "watts per gallon" that is reliable, since with all the different types of bulbs and tubes today, intensity can be the same with so many different wattages depending upon the way the tube/bulb is manufactured. For instance, a 48-inch fluorescent tube in the regular T8 used to always be 40w, but many manufacturers now make a 32w tube that outputs exactly the same light intensity. The 32w is simply made differently so it uses less energy to emit the same light. But again, a different type of tube can be much different at the same wattage. A 32w Daylight 6500K tube will emit more intense (brighter) light than a 32w "Aquarium" tube, which will be about half the intensity. So watts is rather meaningless overall.

Byron.