Just because biofilters exists and just because people have them doesn't
mean they're needed.... With that said:

Bacteria will grow on anything so I don't think you really need a separate
bio filter. They were made popular because aquarium/pond filter manufactures
wanted more money. Maybe if you super duper overstock your pond you would
need one but other than that, the surface area of your ponds and rocks and
normal waste filter are enough. However, if you still want to build one the
key is surface area. The more surface area you have the more area bacteria
will have to grow on. Understand though that bacteria will only exist in
quantities that the food in the pond can provide. So in other words, if you
have 1,000 square feet of surface area for the bacteria to grow on but no
fish (or no other decaying debris, etc) you won't get any bacteria because
there wont be a food source to support them. Also don't over do it with
surface area. For example lets say you have a few fish. Out of that 1000
square feet maybe only 500 of it might be used. At that point you're wasting
your money because there's 500 feet doing nothing.

If you have an existing pond and are wondering if you need a biofilter then
measure the ammonia and NITRITES. If they measure 0PPM then you'd either
benefit from a bio filter OR you'd benefit in moving your water around more.
The bacteria in the pond can't convert ammonia and nitrites if they can't
get to it. Usually still water ponds have bio problems.

If you do need one your media should have a large surface area. Check out
splintered glass media by Ehiem. Fluidizers also provide a large surface
area by utilizing sand as the media.

Sam


"Todd " wrote in message
...
Can anyone recommend a biofilter or good plans to make your own

Thanks
Todd