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Reverse flow undergravel filter for Planted tanks

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I may build my own filter for a 40 gallon breeder tank, it will be a barb and plant tank. The filter will be a sump design with an overflow/skimmer box, the return lines will be on the bottom of the tank. So...

The return line could connect to a series of PVC pipes will holes drilled in and placed under the plant sections (will use gravel) or make a platform will holes drilled into using PVC sheet material from Home Depot.  

I may try a DIY CO2 system (yeast in a bottle) and feed it to the return lines ie: pump CO2 to the gravel. 

Any thoughts?

Edited by madmark285
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Hi @madmark285,

Everything sounds like it should work with the exception of feeding the CO2 into the gravel.  Beneficial bacteria (BB / nitrifying bacteria) do best in a pH typically above 7.0 and will begin to die off below pH 6.0.  Adding the CO2 into the return will likely drive the pH of the substrate (gravel) to levels that will effect BB growth).  I used under-gravel filters for decades and other than the CO2 feeding into your substrate your system should work.  Hope this helps! -Roy

45 gallon (tall) with UG filter


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