I’m considering building a new 2ft cube tank into a breeding tank. It will be a planted tank with wood, not a bear glass tank – as I find a planted tank with a stable biological system is far easier to take care of (especially considering I often fly interstate).

In the past with my last breeding tank, I found that a sponge filter in the tank just didn’t have the guts to do the job, and that all manor of inlet pipe attachments (to prevent fry from being vacuumed into the canister filter) just caused problems that resulted in lots more stuffing around. So last time, I used an under gravel filter with my canister filter intake pipes sucking water from under the baseplate (and it worked perfectly fine until my flat mate turned off the system when I had to fly interstate).

Now I know a lot of folks frown upon under gravel filters, and I agree with most of their reasons. But I found this to be the best solution for my setup last time. So I thought I might bounce some of my ideas off you folks and see what constructive criticism I get.

The problems I found last time were:
Gravel Particle Size – If the gravel is too fine, the larger particles of food will get stuck on or in the gravel. Gravel with a pebble size of no smaller than 5-10mm would be best.
Void Space – The void between the floor of the tank and the base plate of the under gravel filter should be 2cm to 1 inch – anything smaller does not give an adequate flow for the power and can, block up with matter and create flow voids of stagnate water.
Flow Rate – I found that the rate of water flow through my old canister filter just didn’t have the guts to handle the setup to keep the flow of water in the under gravel area at a good level, resulting in low pressure zones. Also pipe diameter restricted maximum flor rate.

What I am considering doing is to make an under gravel filter from scratch. I’m looking at a specially cut plate made from Perspex to form the main base plate, with stand off feet to give a void space of 1 inch. The canister filter should be of a larger variety than I have used in the past (I have taken on an overkill attitude towards canister filters because I am not as fanatical towards water changes as most – and because I aim for a biological process more than just lots of water changes). With larger gauge tubing that I plan to attach directly into the filter base plate – although I am still considering how best to make the fitting to get best flow rate...

But I am in no hurry, I’m still growing out the pair I suspect I have in another tank.