Since you would use something thin, I am thinking plastic clip to clamp down to the background at the top edges. Does pvc run through into the background? You could drill hole and extend the PVC as needed and run through the cover. I think it's doable and reversable if you wanted. Magnets could work but too as mentioned but two things to think through 1) the background isn't flat so you'd have to ensure two magnets can touch. 2) You would have to glue magnets to background...but you dididn't like it anyway.
I think it could look very clean...just cannot suggest specifically around plumbing without seeing it as i dont remember how yours run over / through the tank?
All the plumbing is in the overflows. I just realized theres nothing to clip it to. The top wouldnt allow for it. I think the pond armor would look better, but i like this idea as a test run. Should be relatively cheap to do and i can probably get it to hold with magnets. If i dont like the look i can just take it down the pond armor is permanent. Any ideas on what i should use ? I was thinking poly carb sheets butt they wont sink easily









