Heh. The big 'P' word eh?
Well this is certainly a way to get some fish heads hot under the collar...
A little history. When I started my reef tank in the early '90s the plenum/dsb debates didn't exist. People were trying 'berlin' methods without substrate, others were using crushed coral and some, including myself were trying sand.
Then word crept out about tanks in Monacco that Dr. Jaubert had going using a pvc foundation under the sand. I believe around the same time, I may be wrong, that there were people here in the states like Sam Gamble that were studying why tanks with undergravel filters in them did better when the power was off!
From there the plenum started to become widely adapted.
However, as sand became more and more popular, many people began foregoing the plenum and just putting sand in the tank.
I would speculate that this had a lot to do with people being intimidated by making a plenum and being encouraged by some success stories of tanks without a plenum. Also they may have heard stories of tanks having problems with plenums. You still hear these today, but I have yet to hear one from a direct source. It is like an Internet tumbleweed based on hearsay. I believe some may be true, but I would be willing to bet that they didn't construct the plenum very well.
It may be too early to tell, but I think I am seeing things go full circle as some that are not completely happy with DSBs asthetically or functionally are looking for alternatives. This has also been fueled by the DSB man - Dr. Ron Shimek's recent tank crash and his speculations about 'old tank syndrome' which turned some people off.
My take - both can work well at what they are supposed to do - lower nitrates. BUT they are not the end all be all and will not make or break a tank. What I mean is that they are one piece of the puzzle and other things: water quality, lighting, filtration, tank husbandry, etc.. are equally if not more important.
I tried to put everything I know in the sand section about setup. Check it out:
http://www.3reef.com/sand.htm
Basically, build your plenum with pvc/eggcrate/plastic window screening and put 4 inches of sand on it.
matt
