Advice on using overflow and sump with 25G cube AIO

[Runner]

I just purchased a nice 18x18x18 cube tank (25G) with AIO filtration area in the back. I am exploring the possibility of drilling and adding an overflow to the middle section. Has anybody ever done this?

Also, any sump recommendations? Can go no bigger than 16x16 footprint. Likely will just make it myself, though. Or use a baffle kit for a 10G. But would appreciate any recommendations.

Plan for tank is LPS and softies (zoas) and a few smallish fish. If I go with the sump, it would be as a refugium with sand bed, or location for a skimmer.

P.S. Just getting back into hobby after a few years hiatus, so taking this slow and planning everything before putting water in the system.

 

[*GAREEF*]

Yes, but unless you are familiar with drilling glass , I wouldn’t recommend it. Or at least practice drilling first. Or take it to a glass specialty store.
Also, certain glass can not be drilled.
If your just going to do lps and softies the filtration should be adequate. Does it have a space for a skimmer in the chamber?

 

[Runner]

Pretty sure I can drill it safely. But not taking the chance. Tank is Hydra Aquatics Brilliant Back Filter Rimless Aquarium. The glass is starphire -- at least on the three visible sides anyway. The back filter section is just over 3" wide and there are several nano skimmers out there that would fit, but I fear the skimmate cup would sit too high and be visible. Going to go without the skimmer to start i think.

 

[Runner]

But if I can find a nano skimmer with a low profile cup on top, I will consider it.