"Koen" wrote in message
. ..
Hi,

I've just finished building my swimming pond (50 m3 swimming area with 13
m3
biofilter with lava rock). Construction is concrete brick walls with EPDM
rubber liner.

Any experience with such a setup ?
How should the pump be rated ?
Do I really need the extra filter? The contractor believes that if I only
use my biofilter, the fine debris will eventually clog it. If so, wouldn't
a
smaller filter or even the Zodiac leaf catcher suffice?

The use of lava rock as a filter material is a religious issue. I personally
it's one of the worst materials out there.

1. it's heavy
2. 13 m3 is really heavy
3. it quickly gets coated with mulm and cleaning it is difficult.

I'm assuming you're talking about this device:
http://www.baracuda.com/baracuda.htm
I'm envisioning your pond to be the size of a swimming pool. With the lava
rock coating the bottom or dumped into some kind of biofilter area chamber.
Unless the lava rock is spread out thinly, i doubt the g3 will do much
except wipe the top layer, it probably won't do much for anything below it.

Not having any experience with a pond that size, i'm basing this off my
significantly smaller pond. Unfortunately since your pond has already been
built, it might be too late for these suggestions.
1. bottom drain and a sloping design towards the bottom drain. That way
every time the bottom of the pond needs to be cleaned you can pump the
bottom of the pond into the lawn. (Free fertilizer)

A bio filter isn't really a particulate filter, though it can be. The point
of a biofilter is to provide a high surface area for bacteria that assist in
maintaining water quality.

Please read the rec.ponds faq for more information.