I bought a 38 gallon Aqueon tank and hood about five years ago at Petland. I use colorful "silk" type artificial plants and have a nice array of colorful fish, mostly tetras including long fin red minors, neons, and "featuring" pink, yellow and blue Glo-Tetra (Gymnocorymbus ternetzi).
So I am loving my tank .... and the original bulb in the hood burns out. No big deal I think so I go to Petland to get a new bulb. I told the guy I had artificial plants and he sells me a "Tropical Sun 550K Daylight," 24", 17 watt T8 bulb.
I get it home and my gosh ..... the light is so bright that the fish (and the fake plants) lose most of their color and and the effect is more like a floodlight than an aquarium light.
So here's the rub. In the five years I've owned the tank, I never cleaned the "gunk" off clear the plastic on which the light fixture sits. So I cleaned it off when I replaced the bulb (it was filthy) so I don't know how much of the new "brightness" is attributable to the new bulb and how much is attributable to removing gunk from between the bulb and the aquarium.
So I think to myself ... I'll just go with a lower wattage bulb .... hopefully with some sort of "cool blue" look to it (as oppose to the current "white hot" look).
So I google it and find on the drs foster & smith, there are five types:
Actinic (Blue) Bulbs
Natural Daylight/Plant Bulbs
Aquarium Lighting: Fluorescent Bulb Selection Guide
After reading each description, it appears I probably want a 50/50 bulb ... but it looks like I am stuck with a full 17 watts which appears to be standard for the 24" size. If it's too bright .... I may need to put something between the bulb and the aquarium cover.
Suggestions or guidance would be appreciated. Thanks.