Hi Davidm

Sorry to hassel you with more questions.

You say "The basic idea is upflow filtration through heavy matting with aeration", Skippy dosen't seem to mention anything about extra aeration in their build,(I may have missed it) have you got any air being pumped into your filter?

How big is your pond and what size filter are you using, how many and what size fish?

Thanks for your help so far, I'm pretty sure this is the type of filter that i'm going to build, just need to decide on the right size.

My pond is about 2800 Gals and I will be keeping 12 Koi in there so I'm thinking a skippy of around 100 - 150 gals should do it.
I think that my pump may be to large though, I have an oase aquamax 8000,(8000 litres/hour) but at the moment, with my current filter the flow is so fast, the water is only spending about 1 minuet in the filter.
How does this compare to your setup?

BG