I use a drainage layer no matter what. Built with egg crate diffuser. A drilled piece of pvc pipe will allow a siphoning. I'll post a few picks of some tanks.
This is the pond section of one fire belly tank.


Full shot.

My other fire belly set up

Both have false bottom to support land and let water pass under to pumps and filters.

Here's a few pics of a current build.

Top view. Notice the hole in the center of the false bottom. Thats the pvc pipe so it can be siphoned. The false bottom is foam for support to keep it from moving.

Here's another look at the flooring with the screw top feature we're trying out. This keep the substrate out.(I hope lol.)

I hope this helps you out a bit.

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