22/09/2026
A big acrylic tank on a bog filter, and a fish that will outgrow most people's floors.
Everyone in the comments is talking about the fish. Fair, it's a good fish. But here's the thing with a bog bed: the gravel and the plants do all the filtering, so there's nothing to swap and nothing to rinse. That's the appeal. It's also the catch, because the entire system rests on one pump. Cut the flow and the bed turns anaerobic, and a bed that isn't moving water isn't filtering anything.
So I did what I always do and ran the numbers. Tank volume, then the bioload, then the head the gravel eats before the pump even gets moving. Bog beds normally run a low turnover, and that's fine while the fish is small. Blue mahseer reach 70cm though.
A lot of these builds get sized off the litres printed on the glass. That's usually where they come apart.
Question for the group. What are you turning over on a bog bed, and how often do you actually clean it?