Hi. I'm confused about this....

1. How do you determine the proper flow rate through a biofilter to
calculate say a water change once per hour or say twice per hour?

2. If you have say an 1800 gph pump moving your biofilter.... Does
the resulting spillover SPEED/VOLUME from the biofilter/waterfall to
the pond, vary with the size of the filter tub?

I.e.; if I have an 1800 gph pump. Would I have a different
Rate/speed/volume OUT of the waterfall if I have a 35 gallon bio vs. a
70 gallon?
Would I have a wimpier waterfall with a 70 than a 35?

I'm debating about making a biofilter out of a garbage can (or
similar) vs. a 70g rubbermaid stock tank. I am worried the 70g tank -
because of having more water in it - would dissipate the action of the
pump/waterfall.

I hope my question makes sense even if it might be a stupid question?

That's good to hear!

OK - I also understand the closer the pump is to the filter and the
less tubing involved - give you better flow or more oomph.

I'm now looking to buy tubing. Expensive!

I'm either going to get (2)-1800 gph pumps or an 1800/2400 combo.

The 1800 has an output hole of 3/4"
The 2400 has 1"

Should I get 2" tubing for these 2 pumps? Or 1.5" Which would be
better for more flow or doesn't it matter at some diameter point?

Also - would I need a larger tube to go from my prefilter to my pump
also? Or is hose diameter not an issue before the pump?

I think I would agree with John, I would use the 1 1/2, I think I would also
go with the 1800/2400 combo that way you could run the smaller one 24/7
&both with the bigger one bi-passing the filter for show

"Lisa" wrote in message
om...
That's good to hear!

OK - I also understand the closer the pump is to the filter and the
less tubing involved - give you better flow or more oomph.

I'm now looking to buy tubing. Expensive!

I'm either going to get (2)-1800 gph pumps or an 1800/2400 combo.

The 1800 has an output hole of 3/4"
The 2400 has 1"

Should I get 2" tubing for these 2 pumps? Or 1.5" Which would be
better for more flow or doesn't it matter at some diameter point?

Also - would I need a larger tube to go from my prefilter to my pump
also? Or is hose diameter not an issue before the pump?

"Lisa" wrote in message
om...
That's good to hear!

OK - I also understand the closer the pump is to the filter and the
less tubing involved - give you better flow or more oomph.

I'm now looking to buy tubing. Expensive!

I'm either going to get (2)-1800 gph pumps or an 1800/2400 combo.

The 1800 has an output hole of 3/4"
The 2400 has 1"

Should I get 2" tubing for these 2 pumps? Or 1.5" Which would be
better for more flow or doesn't it matter at some diameter point?

IMHO...go as big as you can afford...you can always put a valve in line to
effectively "make the pipe smaller". Small pipe can't be made "bigger".

BV.