Leigh, you informed me that I had a low light
tank (10 gallon tank with 1x 10w flourescent tube, and 1 x 50w 300 lumens
desklamp). And told me that i should just remove the incandescent as it will
not really be doing any good. I did remove the lamp about a month or so ago
and only had the 10watt going in the meantime. All was fine but plant growth
basically halted in its tracks. They looked healthy but were not thriving.
Last weekend I added 4 Threadfins to the tank (the only inhabitants). I did
a small water change before they were added and while examining the tank I
decided that the plants were definitely lacking something. I put the
incandescent light back on the tank and hey viola....Instant Pearling.
A couple of other things to consider:
* How old is the flourescent tube? The cheap bulbs that come with
some fixtures really drop in output after 6 months or so. An old
10 W flourescent with poor reflectors won't put out much light.
* What is the position of the two lights? If the desk lamp is shining
directly on the plants, it's going to have an effect.
So Leigh's advice may have been spot on, in the general case, but your specific
case may be different enough that you had a different experience.