Reef Central Online Community - View Single Post - Do barbed fittings slow down flow rate? Size of return line?

sleepydoc · 03/21/2016, 08:06 PM

Yes, barbed fittings definitely add significantly to head pressure and therefore reduce flow. I was plumbing a Fluval SP4 and tried it with a section of vinyl tubing and then a section of flex PVC. The tubing had about a 15% drop in flow IIRC. Best way to see this is to look at the size of the hole on a ¾" barbed connector. It's closer to ½"

Can you use spa flex or ultra flex PVC? They will give you the flexibility of vinyl tubing without the drawbacks.

Regarding the return plumbing, plumbing resistance is additive, so even though your bulkhead is 3/5", there is likely some benefit to upsizing the pipe. I'd play around with some headless calculators to try and get an ide how big of a difference it will make.

03/21/2016, 08:06 PM	#2
sleepydoc Registered Member Join Date: Oct 2011 Location: Minneapolis, MN Posts: 3,907	Yes, barbed fittings definitely add significantly to head pressure and therefore reduce flow. I was plumbing a Fluval SP4 and tried it with a section of vinyl tubing and then a section of flex PVC. The tubing had about a 15% drop in flow IIRC. Best way to see this is to look at the size of the hole on a ¾" barbed connector. It's closer to ½" Can you use spa flex or ultra flex PVC? They will give you the flexibility of vinyl tubing without the drawbacks. Regarding the return plumbing, plumbing resistance is additive, so even though your bulkhead is 3/5", there is likely some benefit to upsizing the pipe. I'd play around with some headless calculators to try and get an ide how big of a difference it will make. __________________ ~~~~~~~~~~~~~~~~~~~~~ 120 gallon, coast to coast overflow w/beananimal overflow. Waveline DC 10000 II return pump, 40 gal sump, Octopus XS200 skimmer, T5 lighting