Plastic PIPE fittings offer much less resistance than threaded metal
pipes. Tubing on the other hand is restricted by the barb fittings.
Copper and brass sulfate and is toxic in high levels. If you need a
lot of bends use two 45s instead of one 90 degree elbow, it will
restrict less flow. Or go to a larger pipe for longer runs even if you
have to reduce again to connect.
PVC is the cheapest and least reactive way to go and use ball
valves for best flow.

http://community.webshots.com/user/hankpage1

"Iain Miller" wrote in message
...

"Axolotl" wrote in message
30...
Does anybody have anything to say on the subject of copper/brass
fittings
when building your own bio/mechanical filter system?

I have just built a small filter system for my new pond (2600
gal), and
have studiously avoided using any metal fittings, but I am not
very happy
with the impedance that the plastic fittings introduce into the
water
flow. In addition the range of fittings available in plastic is
not as
great as that available in brass.

Everything I have read here to date seems to indicate that I
should avoid
using metal in fishponds.

Everything you've read is right - avoid all metals (Copper and Brass
especially)

I.