Building a simple sump

Has anyone ever built their own sump? We have a spare tank we want to convert and would be glad of some pointers, especially where cost-efficiency and avoiding leaks is concerned. It only needs to be very simple as it's for a coldwater tank so no elaborate equipment like skimmers etc necessary. Literally a filter, a few baffles, an inlet and an outlet.

Any tips or links, I'd love to read them. Thanks!

How the internal bits of the sump work (ie skimmers or filters etc etc) comes second in the plans.

The main things to think about are: floating the room; avoiding emptying the main tank; and avoiding emptying the sump. ie balancing water flow. Flow out cannot exceed the flow in etc.

They are the bits to work on. The solution depends on the design of the main tank.

I would not recommend thinking about having an active pump out and active pump in. A one way pump system is the best, and then you use gravity and siphon action to balance the flow in the other direction.

The natural place to put the pump is in the sump to pump from the sump.....and not the other way around (unless you are going for an overhead sump).
Return from the main tank should be via a simple gravity or overflow system or a joint gravity-siphon action.
If the main tank has suitable holes drilled in it (at the base or somewhere near the top at the back) then you can use a simple over-flow gravity action (and have good plumbing seals built in).

If you don't have any holes drilled in the main tank then you will need some kind of elaborate gravity-siphon system built onto the tank.

All in all, the holes and tubes for allowing water in and out should be sufficiently large to not cause a bottle-neck of water flow and the strainers should not be easily blocked by debris.

It is easy enough to build.....and easy enough to go wrong if you don't plan it correctly.

ian