Waterfall

Rich · Apr 2, 2012

I need to connect a garden pond pump (submersed) that has a 3/4" male thread outlet to 1.5" tubing that's already buried in ground. Tubing runs up approx 2 feet to top of waterfall.

1) Is it even OK to attempt this? Pump instructions indicate that I SHOULD use 1.5" tubing, but it seems large compared to the 3/4" outlet on the pump. Trying to maximize the water flow I get out of this 1800 gallon per hour pump, but maybe I should be using smaller tubing. Does going from a smaller outlet to a larger tube violate some basic plumbing rule?

2) What fittings can I use to accomplish this? Goal is to connect the 3/4" outlet to the 1.5" tubing, but there's no simple 3/4" FPT x 1.5" barb connector. In fact I haven't seen any such connector with a larger barb than its FPT. I suppose the answer will be a combination of a few connectors, but I can't find all the right pieces.

I'm a novice - please help!
Thanks.

speedbump · Apr 3, 2012

I find it hard to believe that a pump with a 3/4" outlet will do 30 gallons per minute. This sounds more like a bilge pump for a small boat that typically does about 10 gpm.

Anyhow, going to larger pipe will only help, not hurt. The larger the pipe, the more flow you can get through it.

As for the fittings, there are lots of varieties. You will just have to get in front of a fitting bin and use what's available. It may take 3 to 5 fittings depending on what's available. Not to mention a SS Hose Clamp.

Rich · Apr 4, 2012

Thanks for the note. I ordered the appropriate connectors and will give it a shot when they arrive.

Regarding the pump - it's Danner's Pondmaster rated at 1800 gallons per hour, so hopefully it will do the job...

speedbump · Apr 4, 2012

Even though it's called an 1800 gpm, the specs say 1200 max and a shutoff of 15' of head. Add ten feet of head to that and your getting far less.

I can't believe the prices they get for those boat bilge pumps.

Rich · Apr 4, 2012

Funny, you're the second person who's mentioned that (the other was in an online review), but the instructions pdf on the website show 1800 gph at 0ft of head, shutoff at over 20' of head. The name on the box certainly indicates 1800. My vertical head is only around 2.5 feet, and with around 14' total tube length I'm hoping for good flow (once I install the fittings that I ordered). If not, I'll have to lodge a complaint!

Why would they "advertise" an 1800 gph pump if it's really only rated at 1200?