display cases turned aquarium

KingNebTheGreat · Apr 7, 2026

I got 4 display cases from a store that was closing down near me a while ago. They aren't water proof but they are glued with something. A few months ago I turned one into a frag tank by sealing the inside seam with (aquarium safe) silicone and making some custom corners. Currently I am turning 2 of the others into sumps and I want some advice on if I am fine to do them rimless and not deal with the hassle of making more rims for them. I am pretty sure they are made of PETG since they don't seem to be affected by acetone. The glue holding them together seems to be like a welding glue to fuse the pieces together and it is quite strong. This is the seam between the sheets of them:

The other tanks look much better than this one to be clear. This one must have had some issue during manufacturing that caused it to become crazed badly along with the bubbly seams. The other 3 look pristine in comparison to this one. I am breaking apart this one that looks bad for the sheets to make sump baffles in one of the other two.
I'm wondering if the glue holding them together in addition to the silicone (rated up to 30 gallon tank and each of these are 5 gallon boxes) is enough to not need to put a rim on it.
Thank you!

JumboShrimp · Apr 7, 2026

Would love to see a full tank photo, out of curiosity. Sounds interesting.

KingNebTheGreat · Apr 7, 2026

JumboShrimp said:
Would love to see a full tank photo, out of curiosity. Sounds interesting.

Yeah np here's the full tank and the frag tank with the rims

I designed and 3d printed the rims. They are glued to the tank with silicone. As for the space between the corners there is minimal bowing. The frag tank has now been set up for around 5 months with no issues with leaking, cracking, or anything really.

When I get the rest of them set up I will update it to my tank thread with some diagrams with how it is all set up. Because one will be a refugium and the other a small sump since I modified my main dp to not have a sump due to area constraints among other things and I do regret that.

JumboShrimp · Apr 7, 2026

Ah, very nice. Now I understand. At first I thought 'display case from a store' meant something like a Deli counter from a restaurant. LOL!

KingNebTheGreat · Apr 7, 2026

JumboShrimp said:
Ah, very nice. Now I understand. At first I thought 'display case from a store' meant something like a Deli counter from a restaurant. LOL!

oh yeah i see the confusion sorry. That would be a very interesting tank though. Replace the cooling elements with heaters and ensure it has enough oxygen in the water and it would be like one of those aquariums where you can walk through the tube going through it