Freshwater Refugium.

[xxBarneyxx]

For anyone who hasn't heard of it before a refugium (hope I spelt that right) is basically a second tank/container linked to the display tank where typically macro algaes are grown. In a marine tank this has the effect of acting as a bio-logical filter (to lower nitrate) and a secondary effect of giving a place away from predators where small inverts can grow (which eventually get sucked into the display tank for the fish, corals, etc to eat).

What I was wondering is how viable this would be for a FW tank. You would need some hardy, fast growing plants that took their nutrients from the water column but I cant (in my limited experience) see why it wouldn't work. I could see if being of most use on tanks that house large, messy fish where having the tank itself planted isnt viable. I'm not sure how much plant mass you would need to to provide viable filtration.

Just curious if anyone has any thoughts on it or has seen it done?

 

[Colin_T]

it does work on cichlid tanks and general tropical tanks. You don't get rid of that much ammonia unless you have the tank chock a block full of plants and they get heaps of light. I usually recommend having a prefilter on the water pump so it can act as a biological filter and strip out the last of the ammonia before the water goes back into the main tank.

The sump/refugium has the added bonus of providing somewhere to keep the heater and other equipment you want in the tank. This can be a bonus if you have big cichlids so they don't damage it.
Also in rift lake tanks where there is lots of rock, the sump holds extra water thus replacing some of the water that is lost from the rock work.

 

[Spider Pig]

I was thinking about something like this in the future but slightly different.

Essentially have one fish only aquarium, say for predators, or big fish and have another aquarium alongside as a heavily planted community set up. Water is pumped from the end of the first tank to the end of the other. Water is then pumped back from the far end to the opposite end of the first tank from where the water was first removed.

Stocking in a conventional planted aquarium isn't alone heavy enough to provide the macronutrients for the plants, so the waste from the fish only aquarium will add to this. With the added filters pumping the water around this should be more than adequate and keep nitrates down as well. There would have to be some direct connection between the tanks in case one of the pumps broke, to prevent overflow. This doubles as a back up.