Back up power supply

[Sermanley]

is it a biocube? (that's the only specific tank I know with your description), if so there is a biocube group on FB that does custom lights, lids, filters, etc all the time. I have a 4g AIO that I wanted to use for seahorses but I have the same filter issue and I was never happy with any solution. ALthough in my situation, a simple sponge filter without an intake would likely suffice.

It's a aquaclear 110 filter on a top fin 36g bowfront tank

 

[Sermanley]

 

[Reefing102]

The ideal solution would likely be something like a modified 3D printed mushroom cage (Not much if any loss of in flow). Otherwise any sponge should work (would just need regular cleaning). If going with a sponge, I’d probably go with a round sponge designed for a sponge filter.