Hello. My BB with the HDPE (starboard) covering the bottom has about three spots where the detrius gathers. One is the "main" one in that given the water flow, most accumulates in this one spot. It was luck that this large spot is easy to access to suction the detrius out.
I would suggest repositioning powerheads to see if a new spot for the collection of detrius can be made, ie: based on flow and "dead areas".
I bought a piece of stiff clear plastic from PetCetera and cut it down to about 18 inches and attached it to a 10ft length of hose. I then put the hose end in a pail and the piped end infront of a large powerhead in the tank. The siphon is then forced via the powerhead and I use the stiff pipe like a vacuum. Today I siphoned out the large spot, which was a weeks worth of detius and took less than a 5 gal pail of water to do it (18l pail from home depot). I had the new water in the tank and the job took no more than 5 minutes. This is on my new 180 gal.
I have an Aqua Medic Turboflotor 1000 Multi hanging on the back of the tank, and 7 powerheads and a Magnum 350 canister filter for charcoal and phosphate remover. The skimmer collects lots, and any accumulation is behind the rocks, not in the front of the tank. Based on what I'm removing I can't believe that with a sand/gravel bottom it was consistently accumulating in the tank. The bottom is quickly covering in coraline algea - pink spots on all the "starboard" bottom.
If you look at the image in this link
http://www.activepartners.com/regina...cat=500&page=1 the detius gathers in the bottom right hand corner of the tank just behind the large tonga branch rock. You can't see it of course as it's behind the rock, so it's not unsightly, but is easy enough to get to for a once a week cleaning. Because it's so easy I'm thinking of removing it even more regularly. It can't hurt
Fish are: Pacific Blue Tang - 6 inches, Fox Face Rabbit Fish - 6-inches, Koran Angel -5 inches (changing to an adult), Coral Beauty, 3 inches, damsel - three stripe - 2 inches, Scissor Tail Goby 3 inches, and a scooter blenny and lawn mower blenny. No plans for any more. About 85 - 90 lbs of live rock.
Rick