Newb with lighting question

[MurfQ]

Hi,

I'm setting up my old 10 gallon and decided to give a planted tank a go for the first time. My hood is an incandescent one and I didn't want the expense of replacing it, so I located some 15 watt screw in compact florescent bulbs at Pets Unlimited. I figured I'd just put one in which would give me 1.5 watts per gallon. That way I could get some low light plants and not have to worry about CO2 or fertz. Upon closer inspection, when I brought the bulb home, I noticed that it says that it is a high output bulb and is therefore the equivalent of much more wattage than it actually is. They show a diagram where it says one 15 watt is equivalent to three 25 watt incandescents. Now I'm worried that I may have too much light. What do you guys think? I really want to avoid CO2 and major fertz at this time.

Thanks,
Cindy

[Purrbox]

You could actually use two of these bulbs over the tank and not have to worry about CO2. It's necessary to have a lot more light over a small tank like this one in order to reach the various lighting threasholds.

Watts is just a measure of how much light a bulb consumes. The reason that a 15watt compact flourescent bulb is equivelant to a 25watt incadescent bulb, is that incadescent bulbs put out more heat and less light with the same amount of watts. The thing is that incadescent bulbs are nearly useless for growing aquatic plants, so comparing the bulb to an incadescent really doesn't mean anything for this application. The baseline for the "WPG rule" is actually a T12 Flourescent over a 55-75 gallon tank. While compact flourescent are more efficient than flourescents, you're going to have some light lost to since the bulb is self ballasted and restrike (light hitting another part of the bulb and being absorbed). Between these issues and the size of your tank, you should be able to do quite nicely with two of these bulbs.

[drobertson]

The single 15watt bulb will be fine for your 10 gal. All screw in CF bulbs are compared to the much higher watt incandescent bulbs, The CF's are cheaper to run by using less wattage. The watt per gallon rule breaks down on the smaller tanks. You should not need CO2 with that bulb, Just be careful when picking out plants, LOW LIGHT.

[MurfQ]

So, if I put in 2 of those bulbs, could I go with some medium light plants and still not have to worry about CO2?

[rich311k]

That is correct. The watts per gallon rule breaks down over small tanks and those bulbs are not as efficient as the tubular ones, due to restrike issues. Plus the reflector in your hood is probably not that great either.

[drobertson]

I use a 11 watt and a 23 watt on my 10 gal with no CO2, I do use excell for a carbon source. I use 1 ml a day, and I have medium light plants that are doing great.

[MurfQ]

Awesome. Next question: is there a website that I can go to which will show me the light requirements of various plants? Preferably one with pictures as the shops around here are notoriously bad at labelling their plants...

[Purrbox]

PlantGeek
Tropica
PlantFinder - Must be a member to use.

[drobertson]

Fantasy Reef also has a nice plant directory.

http://fantasyreef.com/

[MurfQ]

Thanks much! I will check all of those out.