[mxett]

Originally posted by hahnmeister
I read you plan on putting silica in the RDSB... bad move. Silica is glass, and therefore it doesnt breathe very well at all like aragonite. Also, the glass may seem fine and soft on our skin, but its murder on fish gills, as well as any other organisms that have to live in it. Also, the acids that develop in a DSB/Plenum allow phosphates to bind with the calcium in aragonite: without the aragonite, this wont be possible and you will have a phosphate factory.

So I would suggest two things...
1. make the RBSB from aragonite, perhaps a coarse grain for about 3", and then a screen on that and topped with a finer grain (not sugar arag though, but .5-1.5mm arag) on top for 2-3".
2. make it a plenum. research is showing that in the long term, DSB's act as nutrient sinks, but when they fill up, they can backfire. The reason is that they lack the large open anoxic zone of a plenum. So get out the eggcrate! The two DSB's I ran were both plenums, and the cool thing was that I had a pipe running under the plenum with a valve to drain it. This was cool because once a month or so I could drain off a bit of that foul water from in the plenum, detritus, etc... to keep it from clogging up. I only did maybe a gallon at a time, usually 1/2 that, but Im sure it kept the plenum in much better shape because it prevented buildup.

Thanks for the advice. However I've seen Dr Ron Shimek recommend fine silica sand for in tank dsb's. Not that I don't believe you but I've used one before with silica and it worked well, and I'm happy to trust Ron.