DIY nano sump?

[Flyby Stardancer]

Does a sump always have to be at a lower level than the tank, or for nano tanks can it just sit behind?

I'm taking inspiration from this nano sump for tank I'm working on, though my tank is a bit larger than his.

Changes I'm thinking of include having bio media in a container with the pump's intake and mechanical filtering outside of it... I'd also be doing a PVC overflow, since I don't want to risk cracking the tank.

My tank, even though I've been calling it 6 gallons, is closer to 7 or 8 gallons. 18"x8.5"x12".

Any thoughts?

[Strider199]

A sump is just more capacity for your water filtration system. It can sit where ever it fits. The reason most sumps are located under a tank is that the water from the display tank can be brought to the sump with gravity and the sump will most likely be hidden from view as it some times contains skimmers and other equipment.
If you want to use a pump to move the display tanks water into a sump you can have it higher, beside or behind your display tank. You may have to have a secondary pump to bring the water back to your display tank if gravity isn't an option. The down side to this besides having more then one return pump, is in a power failure one of those vessels may over fill. But that can happen with a sump under your display tank also. It's a balancing act to get the volumes right so a power outage doesn't give you a mess.

[Cliff]

You could set it were you want. But you would need one tank to sit higher than the other so you can drain water from the higher tank into the lower one and have a return pump move water back into the higher tank

I would not suggest using two pumps. Even if you get pumps that are the same make and model, there will be a be a very slight variance in flow rates, even as little as 1/8 gph. That would be enough to cause problems in a smaller set-up

[Flyby Stardancer]

Well, the water levels in the two tanks would be inherently different, which would encourage water to siphon from the overflow into the sump... I think I'm a bit worried that the difference might not be enough for the overflow to keep up with the water being pumped back in, if it were set right behind the tank.

What I'm thinking of having in the sump is just the pump, two forms of filtration (likely a sponge for mechanical, plus some sort of biological filtration), and the heater. This tank isn't going to need a lot of equipment, but it's small enough that I do want to keep as much as possible out of the tank itself.

[Cliff]

Google HOB (hang on back) refugiums.

I think that might be along the lines of what you are looking for. That is very common among people who keep small salt water set-ups

[Flyby Stardancer]

Did a quick google search, and I might be able to get some tips from those... Though they aren't quite what I'm going for either. What I'm looking to build is most like a sump, in that you have water overflowing into a separate container, and then being pumped back in once it's been filtered. However, the small size is what prevents it from having the classical sump set-up with the three chambers, and is instead one larger chamber. The only thing I want hanging on the tank is the pipes that get the water between the tank and the filter.