I'm so confused because I just visited a local pond place where the guru in charge told me that my home built "skippy" filter (rubbermaid stock tank upflow type) was an "anaerobic" system but that his filters (downflow type same as mine only in reverse order but without a settling chamber) was the "only" way to go.

So basically you have a big plastic box and water from the pond goes into this box either at the bottom and comes out the top or in the top and comes out at the bottom (and the box usually has at least two layers but often three (settling chamber, bio material layer and filter layer).

So what's the diff whether your water flows UP or DOWN?
Why did he describe my skippy upflow filter as "anaerobic"? I am having muddy water clouding problems and consequently cleaned out my settling chamber (where I found some sludge (but not a lot of it) and it was (of course very STINKY) and I cleaned my filter material etc. This fella said the stuff in the filter should never smell bad...so is he assuming that because I had stinky sludge that my system was anaerobic?

Can somebody please explain in simple terms what this guy might have meant? and if there is a difference between upflow and downflow filters, explain WHAT the diff is?

Thanks for help!
Kathy

If your sludge/filter media is stinky, chances are they are (the bacteria) is operating without O2.

I've not built my own filter, and just own a pressurized UV filter.

Good luck.

Never clean off all of the filter material at one time.
Always leave some of the filter material "dirty".
This will re inoculate/re-seed the rest of the cleaned material, with the "good bacteria" which is required, to keep the pond water healthy.
"Horton".