"Rick" wrote in message
...
I have some light bulbs labeled T12 and some T10 and see some in catalogs
listed as T8. What is the difference, they appear the same to me. And while
I'm at it, are 2 40watt (80w total) bulbs enough to support plants in a
90gal tank? Seems to keep the plastic ones alive

Damn, the Algae killed my plastic plants.


Rick,

I don't think 80 watts will do it for you. I'd want at least double that to
give you close to 2 watts per gallon.

If you prefer a different religion, a 90 gallon is 48*18 or 864 si and your
lights will only give you 6400 lumens (80 * 80 lumens per watt) when new.
The figures I've seen are 15 lsi (lumens per square inch) for low light
plants, 22 lsi for medium light plants and 30 lsi for high light plants. Of
course this all varies with the clarity of your water, the efficiency of
your ballast, the quality of your reflector, the depth of your tank (not so
much) and the phase of the moon.

If you're serious about growing plants, check out AH Supply. Great product
and service.