Well, I tried the bb thing for a while. It was great for about a month, then I started noticing my corals didnt seem as happy (softies) and they didnt open up as far as before. For some reason over the last few days i've started getting hair algae on a few spots here and there. Mostly on the skimmer PH. The glass has to be cleaned at least twice a day, and even that isnt enough. You can see in the pic how the tank looks. Sooo, i've decided to go back to DSB. I like the salt and pepper look of black and white sand, so i bought 4, 5lb bags of black and 3, 5 lb bags of white. (any feedback on this would be great before i start this project) I also bought a sheet of acrylic and some rigid tubing to build rock stands. Thats where the questions start coming in. For example, how deep should a DSB be in a 16gal bowfront? How far should the rocks be lifted off the sandbed? I've added a couple pics so if anyone has any suggestions or things i should change I would like to here them. I'll be doing this projectthis evening, so i havent started anything yet.

You want the sand to be a minimum of 4" deep. I would start with at least 5" because it will compact. Is the grain size the same for both colors? Otherwise you will end up with layers instead of a mixture.

Yes, the grain size is exactly the same. Its soaking in buckets right now and i think it looks great all mixed together.

How far off the sand should i have my rocks? Im gonna make stands for them. I was thinking maybe an inch or a little less, but i wanted to ask around to make sure.

Thanks!

I don't have my rock on stands, but I will add them the next time I re-aquascape, but I seem to remember that it only needs to be a little bit. The idea is to allow the water to circulate beneath the rocks and help to prevent dead spots.

Here's my two cents on the idea of raising your rock: The idea originally (I believe) came from the Jaubert "Moncaco" style of reefkeeping where you would have a deep sand bed with a plenum but leaving most of the sandbed exposed. The idea behind the system was to have organisms in the sandbed "pump" nutrients down into the deep sandbed where there was little oxygen and anaerobic bacteria would break down these wastes (NO3) into Nitrogen gas. So it was necessary to have a large part of the sandbed exposed in order for it to work properly.

If the reason you're wanting to lift up your rock is to do this, then an inch or two would be fine. If you're doing this for extra circulation around your rock then I recommend you just be creative about stacking your rock. I have the exact same tank and what I did was to create lots of caves and space between the rocks on the lower levels. Obviously you want it to be stable so big rocks go on the bottom. It's actually recommended to place your rockwork first then pour your sand in around the rock because this would stabilize the rockwork and prevent shifting after it's full of water.

The point here is that you actually WANT less circulation in some areas. You want there to be a gradient of oxygen levels because it's in these areas where de nitrification takes place. It's a delicate balance for sure. Besides, who wants to look at egg crate and tubing? lol. Keep good circulation throughout the tank and behind the rock and you'll be fine.

Hope this helps.