[Wet Thumb Forum]-Setting up a sump for a larger tank??

[Nillo]

The best way to have a sump with minimal CO2 loss, is to have the sump and the tank on the same level. Instead of having the sump underneath the tank you place it beside it or behind it. This, of course, takes up more horizontal space but does have a few advantages.
The first is that it is impossible for the sump to overflow in the event of a power outage. Even if you just had a direct siphon from one tank to the other, they would just balance out.
The second is the lack of head. Since you don't have to push water up 4 or 5 feet, fighting gravity all the way, your pump if far more efficient. Because of this you have the option of either getting a less expensive pump with lower head, having an enormous amount of throughput from a big pump, or creating head for the big pump by using manifolds and multiple small outlets placed throughout the tank.
Plant tanks enjoy the benefit of not needing large sumps, and oxygen exchange towers. We just need a place for unsightly equipment, and some mechanical filtration. With a tank that is 30" FTB you could easily have a sump that is 6" x 30" x 18" and have more than enough filtration. I recommend machine washable filter socks.

[Aqua Dave]

The spiral idea is something I thought of as well. I don't know how much it would help, but it couldn't hurt. The key to me is to have your drain pipe terminte under the water in your sump.

Most of the stuff I've read suggests and what I'm doing is to do the mechanical filtration the first thing in your sump. You could place a filter bag or sock around your drain outlet or use a filter pad in one of your baffles. Then you could use a polishing block to remove really fine stuff.

I'm using an external pump with no problems. I'm thinking about going up a size to get a little more flow, but the cool thing is that I can just take out the current pump and slap in the new one without having to do anything else. I have my CO2 reactor and UV sterilizer after my pump on the return line to the aquarium. I would suggest oversizing your pump a little as you can always use a ball valve to restrict the flow some.

Depending on your overflow constuction you may not have a problem with your sump getting filled up in a power outage. My overflows are constructed such that only a couple gallons of water goes into the sump if the power goes out.

I personally like using a sump and planned my aquarium to use one.

David