I will be putting some sort of FW tank underneath my 40br reef. It will be either a 10 or 15 (or even 20), but I am leaning more towards the 15. I know everything I am going to do as to filtration, heating, decor, etc, but I have this idea that I don't know will work or not.
I want to try Dwarf Puffers. I know about all their feeding habits, and feeding frozen or even live foods is fine. But I still want to get back a betta or two, without the addition of more tanks. I think you know where I'm going here...
15G Tank (24"x12"x12"). Divide off 4" on both ends of the tank, leaving about 2.5 gallons in each end, which makes the middle compartment 10 gallons. I would put 3 DPS in the middle (3.33 gallons per puffer), and then two bettas on the outsides. I would make sure that the dividers I get have small enough holes so that the DP's can't fit in. I could also probably put a wall of plants in front of the dividers.
The filters (Penguin 100) will be in the middle, so the flow is still slow for the bettas. Heater in the middle as well.
I will also most likely be using fake plants and both real and fake decor.