Reptile & Amphibian Forums

Lets see if i have this right. CF give off more heat then normal flourescents also the higher the wattage the greater the increase of heat. And for supplying light to my vivarium I would want to get the greatest amount of lumens as I can with the least amount of heat? So for my 30g cube about 20x20x20 what wattage screw in CF would be ideal and how many would I want to get the best results.

Thank you very much

CF's do give off a good deal of heat. However, a great amount of the heat associated with the CF's comes from the ballast. Therefore, if you buy a kit that uses the straight pin type bulbs (like what is sold at AH Supply, you can locate the ballasts on the back of your hood (away from the bulbs and away from the terrarium), and reduce the heat output that affects the terrarium. This is one way that the straight bulbs are better than the spiral type bulbs.

Another point is that yes, the higher the wattage of the bulb, the more heat it will give off. However, if you use one 36 watt bulb instead of three 13 watt bulbs, you will have less heat from the one 36 watt bulb than the three 13 watter's. This has (mostly) to do with the ballasts as a point of inefficiency, but you will also note that there is a slight increase in efficiency of lumens per watt as the individual bulb wattage gets larger, in most cases. That should translate to less heat, but it will be negligible.

As for a 30 gallon cube of your dimensions, if you are really set on CF's, I would either recommend a 2 x 36 watt kit like those sold at AH Supply placed across the top for super duper plant growth, or you might try a couple of those CF task lights like Matt is talking about below. Of course, you could also double the amount of wattage and just use 18" standard fluorescent fixtures. Really, the question is how many lumens do you need, and what are the respective prices for the fixtures and replacement bulbs.

If you want me to pontificate more, I will, but I'm starting to feel like I might be rambling.
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Homer W. Faucett III, esq.
Purveyor of Trivialities and Fine Nonsense

I agree, ah does have some nice kits, and I also agree that the higher the wattage with these types of bulbs the efficiancy also (usually) goes up. for instance, according to published numbers, a 55watt bulb can produce more light than 2-36 watt bulbs. I don't know if it would fit over your tank though. 55watt bulbs generally run about 23 inches long, if I remember right. maybee it would fit corner to corner? There are also flat quad compacts. Check out the lighting links on doyle's dart den for a lot of info on lighting.