Also .. have you considered using something like a med sized tub just as the water area and building a deck land area around it?

use plywood as top layer around the tub, water seal the plywood, then put some astro turf over the plywood ... I did a set up like this years ago but instead of a tub I used a kiddie pool, it worked out pretty well.

You could do land area on all 4 sides .. on 3 sides or even just on 1 side ... anyway you like.

You could use a canister filter like a fuval fx5 or etheim thermo canister filter and hid the unit under neath the land area, hide all the plumbing under there also.
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Great Lakes Zoological