One size fits all?

[AbranV]

I would suggest you get an 18x18x24, at least. The main reason is that extra height is really nice in almost all situations because it gives you more flexibility with plants. 18 inch or smaller vivariums just really restrict you to very short plants. I have seen people with 3 tinctorius in 18x18 foot print vivariums and an 18x18x24 will also house a group of thumbnails. That said going with a 24x18x24 would be even better.

I have a 29 gallon with the front broken out. I've tossed around the idea of getting another during the PETCO sale. Then taking the front off and attaching it on top some how. This would give me something like a 30lx18wx24h footprint.

I've also thought about Frankensteining two 20 gallon tanks into a 24x16 cube