Plenum for Freshwater?

[The Gipper]

I've seen a few posts regarding plenums. Anyone maintaining a plenum in a freshwater plant tank? If so what for and how do you do it?

Thanks

[RTR]

I have several FW plenums, just as a test to see if they do function in FW. The construction is exactly the same as the SW plenum using PVC pipe sections for support, egg crate light diffuser grid, and fiberglass mesh screen. I omitted the mid level screen ro avoid root entanglement in planted tanks. Mine do work in that they reduce nitrates, meaning that my moderately lighted non-CO2 tanks have to have nitrate supplement just as do high light, pressurized CO2 supplement tanks. Other than the nitrate reduction function, they operate as would any other planted tank.

For me is is/was just a long term experiment. When mine were first set (~5 years ago),many folk said that plenums could not work in FW. That proved to be mistaken, another case of people deciding things without ever testing them.

I'll keep them running at least to a total of ten years (my normal tank setup projected life). I see no great advantage nor disadvantage to them for moderately stocked tanks. If you have chronic high nitrate readings and this is a problem for you, the technique does work for me, but it is not a quick-fix by any means. It is slow to establish the nitrate-reduction function, maybe 4-8 months. Increased water changes woulf be faster and simpler.