01-18-2005, 05:04 PM
Join Date: Jan 2004
Location: Dallas, TX
iTrader Positive Rating: 100%
The "blue" bulb is the so called "actinic". They are used to stimulate growth of algae in saltwater tanks.
You can use a "blue" bulb over a freshwater planted tank without stimulating algae growth. But the plants will not benefit much off it.
220 watts of white light over a 55 gal. tank make it very "high speed" - meaning the plants will grow fast and eat nutrients extremely quickly untill they run out of one nutrient. At that point they stop taking nutrients and if you don't replenish the missing one you will most likely end up with algae taking over. The problem is that you may not be able to find out which nutrient you need to replenish before algae creeps in. The whole thing is very fast - plants can suck nutrients in the matter of hours.
Depending on how the bulbs are wired I'd say try to remove the two "blue" bulbs and use only the white ones. You may not be able to run only 2 bulbs on that fixture witout rewiring. With 110 watts of light, (2 watts per gallon) - you will have a good amount of light over a 55 gal tank without the "high speed" issue. Cabomba should do good with 2 wpg.