Fuge

[Mr_Cool]

I'm building a small fuge for my 55 galon. I'm going to have a small chamber for some live rock rubble, and the rest will be for live sand and macro algae. It's only about 9 inches tall because I don't have a lot of room to work with. I really just want a place to grow some macro algae for nutrient export. So here's my question...

If I already have a 5-6 inch deep sand bed in the main tank, how much sand should I put in the fuge? If I go much more than 3 inches in the fuge, I'll only have about 4 1/2 inches or so of water in the fuge. Is this enough? Or, should I just keep a small layer of sand in the fuge (like an inch or so) and have a little more water?

Any opinions would be appreciated.

[blueboy]

sand is not nessecary in the fuge, i would just use rubble, and some chaeto, one of those CF lights from depot, and a small pump, just enough to keep the water moving a bit.

[Louie3]

well, in my 10g fuge I have 20lbs in 1 section about 6-8 inches deep and a pice of rock a smashed with a hammer. but ever since that my levels are perfect

[Mr_Cool]

Actually, I'm not planning to use a pump. Everything will be gravity fed. I am going to put a T in the drain line from the overflow with a ball valve on the side that leads to the fuge. This way I can controll the amount of flow to the fuge, and whatever water that is not handled by the ball valve will back up and go into the sump through the other side of the T. The fuge will sit a higher than the sump so that water will over-flow through a bulkhead down into the sump. Then, the water from the fuge will mix with the water in the sump and be pumped back up to the tank through the return pump.

I think I'll try a small layer of sand with the rubble. This way, I can always add more, or even take the sand out completely if I want to later. Nice to know it doesn't really matter, though. I know that my denitrification is going on in the main tank.

[hobogato]

the last step of the nitrogen cycle is the one that a deep sand bed will perform. chaeto will also get rid of nitrates. the live rock in your tank and the shallow sand bed do little nitrate to nitrogen conversion, so without a way of exporting the nitrates (like macroalgae) you may get a small buildup of nitrates. the reason a deep sand bed gets rid of them and a shallow one deosnt is, the deep sand bed allows for an anoxic zone for facultative bacteria to change nitrate to nitrogen. a shallow sand bed does not have an anoxic zone, so those same facultative bacteria will not change nitrate to nitrogen.