question on algae and UGF filtration

"Eric Gutierrez" wrote in message
m...
I've got two 3month old 100 gallon freshwater aquariums. (72" x 18" x
18")
No gravel, just bare bottom with a few (less than 10) handsize rocks.
Cleaning (all water drained) takes me 6 hours total...a pain...

My first problem is green water, the tanks cannot be placed in another
location, and direct sunlight hits them for 3 hours per day (6am-9am).
Question: What can I do to eliminate this? The water turns cloudy
after 3-4 days of a complete water change, then green in about 4-5
days. In two weeks, you can't even see the fish, the water is totally
green, but you know they're still there, coz the food disappears.
I am now covering the aquarium with a car-sunscreen hoping this would
work.

Second is on filtration. My earlier installation was just a powerhead
(up to 1200GPH) connected to a 4-stage box filter on top of the
aquarium. Somehow, I thought this was inadequate. I decided to use
the same powerhead to drive a UGF, plus another airpump connected to
an airlift tube on the other side. The powerhead sits very close to
the plate using only a short 2" updraft tube. I am still not using
gravel, just some kind of 1" thick white cotton like substance
normally used as filter media covering the entire UGF plate. Question:
Is this alright? I'd like to avoid gravel, coz it will be a nightmare
trying to clean this aquarium with it.

Thanks for any advice, guidance, tips.

eric
ericag_ph @ yahoo.com

Use a UV unit. Clear in a day.