Would bio balls work with this filter? And what size pump would I need?

[Miyavp]

I'm building a pump that looks like this out of a milk jug. Would putting bio balls and allowing the water to flow through them work? Putting some sort of sponge at the bottom to slow the water flow a little maybe? Also would I need a super powerfull pump for this? Could I just hook a tube up to the outtake of my 40gal submersible filter and run that through this?

[Miyavp]

Wrong picture sorry

[Miyavp]

This filter not that one. Its almost three in the morning here sorry.

[Fresh2o]

I used to frequent an LFS about 20-25 years ago (wet dry filters were taking off at the time) and they used this type of setup in a lot of their larger tanks. Have not been back there in a while so I don't know if they continued to use them. I have seen this setup in pond/aquaculture systems.

This would work, however, there are a few things to consider. You would want to prefilter the water so that solid waste is not added to the bio media. Else you would encourage the growth of heterotrophic bacteria (I believe bacteria in the nitrogen cycle are autotrophic). If you are growing plants in anything above low light conditions, a portion of the injected CO2 would be removed with this setup.
Otherwise, for ammonia/nitrite processing this should do. Good luck. Record your water parameters so that you can see how effective this is.