plumbing question


Lifetime Charter Member
Lifetime Member
Nov 21, 2007
Los Angeles, CA
I need to attach a return line to a underwater pump in my sump. It is a 3/4" outlet and my clear 3/4" flex tubing fits over it tightly (but I doubt I will need to heat it up). I'm not confident that the flex tubing will hold under pressure, especially since there is not a ridge that the flex tubing must be forced over. I would like to avoid spraying the water in my sump all over my room. :)

What's the best way to make sure that the flex tubing stays on the pump? I would rather not do a "permanent" attachment that cannot be undone, although I would not mind permanently attaching a coupling with male threads on one end. Is there some sort of glue (PVC cement) that holds on to plastic and PVC both? Or perhaps I should use a clamp of some sort -- I have both plastic and metal clamps. The last time I used a metal clamp I really bent the heck out of pump's outlet (and even with the clamp, the connection came apart a couple of times rather easily). Any other ideas?


Plant Guru Team
Lifetime Member
Sep 23, 2007
South Florida
Hi Ted,

I did the following for my Mag drive which is as you describe with no slip or barb fitting.

I used a ball valve first which threads onto the Mag drive. I then used a connector or two (at the LFS) to place a barbed end after this.

The flex hose slips over this along with a hose clamp.

No leaks or spray.

If you need a pic, I am pretty sure I have one.........

Or, use a PVC slip bushing or two to achieve the same affect if your outlet is not threaded.............

A trip to the plumbing section should set you straight in a few............


Lifetime Charter Member
Lifetime Member
Jan 24, 2005
Sacramento, CA
Virtually none of the pumps or powerheads we use produce much pressure. They use a fast turning rotor that pumps by centrifugal force pushing water out the outlet. Their maximum outlet pressure is usually around 1 pound per square inch or less. This is not enough pressure to force a hose to come loose from a fitting, if it takes any force at all to push the hose onto the fitting. For example, for a one half inch diameter hose, which has a cross section area of less than 0.2 square inches, the maximum force, if the pump produces a maximum of one pound per square inches, is 0.2 pounds or about 3 ounces.

The risk of "blowing" a hose off the fitting is very small, but handling the hose, vibrating the hose, jerking the hose, etc. can pull the hose off sometimes. That's the reason for the barb on a hose barb, or the use of a hose clamp.