2 cannister filters hooked up to one set of suction/discharges?

[doug z]

Having a heck of a time figuring out how to position the suction/discharges for both cannisters..

ONE I could handle, but both..

My plants are getting blown about, the substrate directly below the spraybar is disturbed excessively when I place the spraybar vertically, it's hard to hide both of them, if I went with lily tubes where would the other one go, etc..

One solution I heard was to hook up both cannisters to one suction and one discharge line..

Is this at all practical?

Would the flow rate be doubled, or the same?

Has ANYONE done this?

[james481]

I've never done this, but I suppose it should work, provided that the tubing used is large enough to handle the capacity of both filters. Of course, with typical canister filters, this means you're probably going to need to run 1 inch line for both inflow and outflow. I'm not sure if hiding a one inch inflow will be easier than two half inch inflows, but also consider the flow pattern you need in the tank. Two outputs may actually be more appropriate for a good flow pattern.

ETA: Also, consider that every tee, ell, valve and foot of pipe you incorporate into the system will lower your flow rate, sometimes drastically. Make sure to consider how powerful the pumps in your canisters actually are, and that they can maintain a good flow rate through all of the plumbing you're going to put on there.

ETA Again: Also, upon further consideration, I would probably plumb this with hard-line PVC instead of flexible vinyl tubing for safety's sake. For instance, consider what would happen if one of your connections on the outflow side started leaking. The entire tank (down to the level of the intake) will drain by siphon onto your floor...

[robnepper]

Hey Doug. Here are two formulas to help you on your way.

I don't know how to write them on a comp... so here goes.

Solving for flow rate:
1/4 * 3.1415 * ( pipe diameter squared) * velocity.

solving for velocity:
4 * flowrate
------------
3.1415 * pipe diameter squared

There is one more to get pipe diameter, but that will be known. You should have flow rates on the pumps whick will probably coincide with the hose diameter that was supplied. These equations are probably not as accurate for flex pipe as there will be more turbulence. Going to a bigger dia. will definately reduce flow rate.