Lighting for 2 foot deep tank
I have used standard 48" FL shoplights (4, for a total of 8 x 40 w = 320
watts of light) on my "optimum" 120 gallon, 2 ft. deep tank for the last
year. Plant growth has been generally good, though some plants that
prefer stronger light (Hygrophila sp., Mexican Oak Leaf) have not done as
well as I had hoped.
I was particularly encouraged by the growth of E. quadricostatus and
Anubias nana, which I placed in the relatively dim foreground areas.
However, E. tenellus has not done as well. In order to encourage better
foreground growth, I have recently added three 20 w flourescent spot
lights aimed at the foreground. These are 2800k lamps, so while the
spectrum is not ideal, they do produce a neat simulation of shafts of
sunlight reaching through to the bottom. Do they speed up growth? The
jury is still out on that...
These fixtures are mounted on a massive hood, which is suspended from the
ceiling by chains, so that it can be raised and lowered with some
effort. I recently refitted two of the fixtures with electronic ballasts
and T-8 bulbs, which has made the hood noticeably lighter.
So, normal or T-8 flourescents have worked quite well for undemanding
plants in a 2 foot deep tank, and if you "roll your own" hood, they are
much cheaper than MHs.
- Jack O'Leary