# Planted wet/dry filter? Water treatment plant?



## MacFan (Jul 30, 2006)

I'm not sure if this is the right topic, but it seemed close as it's sort of an advanced idea. I have purchased a 72 bowfront that I will be building to host Discus. It will be heavily planted and will be open top with suspended lights and plants growing out the top and probably around the tank. 

I'm planning to build a stand for the tank and to build it a foot or two deeper than necessary. Originally my intent was simply to make room to place plants behind the aquarium and as a place to hide plumbing. But last night I got to thinking, what if I built a sloped tray that ran the length of the tank and extended 12-18" behind the tank. I could then plant it with an appropriate combination of substrates and bog plants, and basically pump the aquarium water to the top edge and let it cycle through the substrate back into the tank. In a way, I imagine it would be sort of like a wet/dry filter in concept, but with plants to aid in waste breakdown. A bit like a septic field for those who lived in a house without a sewer system. The tank has an overflow in it for saltwater, I could fill it with bio media and a sponge if necessary, but the idea was perhaps I could do this instead of a typical canister filter. It would look cool and be more technically advanced. But I don't know what capacity it could handle and whether it would really be all that effective. So I defer to the advice on this forum... 

Michael


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## Laith (Sep 4, 2004)

While I applaud the creativity, I'm not too sure that you'll get any major incremental improvement in biological filtration over just the heavily planted tank.

A heavily planted tank with healthy plants will eat up all the various N compounds produced (NH3/4, NO2 and NO3) without external biological filtration, at least in my experience. I guess though it depends on your fish load. If you have an overload of fish then possibly this won't be the case. But a 72g won't hold more than 4 to 6 adult discus and a heavily planted tank can handle this bioload.

I run cannister filters on all my planted tanks but more for circulation and as a backup biofilter. I can remove the cannisters from the tanks and see absolutely no spike of anything. In fact most people need to add Nitrates or the plants will starve...

Your idea would have a more positive biofiltration impact on a non-planted tank, similar to refugiums used in marine tanks...


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## ruki (Jul 4, 2006)

I've seen this approach work really well for marine tanks. The filter tank had green leafed salt water plants cleaning up for the reef tank above.


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## DataGuru (Mar 11, 2005)

Here's the plant filter I had set up when I had goldies in my 55 gallon tank. I now have cichlids in that tank and wanted to do a Walstad-type natural planted tank, however, I also needed to keep the holey rock and wanted some sand for them to do their thing in, so there wasn't enough room for soil and plants. 









I ended up putting potted plants along the back of the tank and converting the plant filter to a natural planted tank. (Soil substrate covered by an inch of gravel and heavily planted). The only mechanical filtration is the foam filter between the tank and the plant filter.

The only drawback I see to using the tray like you're thinking is that debris would eventually build up, perhaps to the point of needing to clean it.


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## czado (May 26, 2005)

Agree with Laith and DataGuru. Wet/Dry is either redundant (I would call it unnecessary, as Laith said) or counter-productive (when injecting CO2). A planted filter is nice though, and at the least will help in nutrient export. A heavily planted main tank with regular trimming and water changes will have plenty of nutrient export, though.

For your consideration, you may just want to consider a sump, if only for the ease of water changes and the higher volume for your (said to be) sensitive fish.


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## ruki (Jul 4, 2006)

Another thought would be to have giant duckweed in another tank as a filter. There have been papers written about this removing all kinds of crud from the water. Just keep scooping the excess nutrient gorged plants each week. This would be perfect food for goldfish.


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