Only getting 97 GPH with UV Sterilizer

[Nick4978]

I have 75 Gallon mixed reef tank with a sicce return pump that outputs a theoretical 950 GPH connected directly to a neptune 1" flow sensor and then from the flow sensor out to an Aqua ultra 25W UV (max theoretical flow rate of 800-1200 GPH) and then out to my display - nothing else in-between. According to my Apex monitor, I'm only getting about 97 GPH through that flow sensor. I've taken the pump out and cleaned it and opened it up wide open, but it didn't change the flow rate. Both the flow sensor and UV are new. Should I be getting a higher flow rate? The UV sterilizer says to get rid of bacteria, it should run closer to 400 GPH and for general water clarity, about 800. I'm a long way from either of them. At 97 GPH, is it actually doing anything? For that matter, is any of my sumps filtration, skimmer, reactor, etc doing much since at that rate it's only cycling all of the display water just over once per hour? And if necessary, is there anything I can do to increase the flow? Or is that UV slowing it down that much?

P. S. - I haven't checked the flow without the UV because I got them both at the same time and plumbed them together. It would be a PITA to do as a troubleshooting step so I wanted to ask here first to see if this was normal before doing it since I've read various articles with different opinions about a UV slowing down the flow rate.

 

[Ben.QLD2]

I suspect the problem is head height. Pumping vertically is a big killer of flow rate. A UV system is essentially an empty vessel that just directs water around a UV tube, it shouldn't impede flow.

Unless it's one of those fancy spiral type units that their own internal plumbing?

I would say the problem is either head height and the pumo can't handle it, or there is a tubing kink or blockage somewhere.

 

[gbroadbridge]

I have 75 Gallon mixed reef tank with a sicce return pump that outputs a theoretical 950 GPH connected directly to a neptune 1" flow sensor and then from the flow sensor out to an Aqua ultra 25W UV (max theoretical flow rate of 800-1200 GPH) and then out to my display - nothing else in-between. According to my Apex monitor, I'm only getting about 97 GPH through that flow sensor. I've taken the pump out and cleaned it and opened it up wide open, but it didn't change the flow rate. Both the flow sensor and UV are new. Should I be getting a higher flow rate? The UV sterilizer says to get rid of bacteria, it should run closer to 400 GPH and for general water clarity, about 800. I'm a long way from either of them. At 97 GPH, is it actually doing anything? For that matter, is any of my sumps filtration, skimmer, reactor, etc doing much since at that rate it's only cycling all of the display water just over once per hour? And if necessary, is there anything I can do to increase the flow? Or is that UV slowing it down that much?

P. S. - I haven't checked the flow without the UV because I got them both at the same time and plumbed them together. It would be a PITA to do as a troubleshooting step so I wanted to ask here first to see if this was normal before doing it since I've read various articles with different opinions about a UV slowing down the flow rate.

I suspect that the flow sensor and other plumbing is restricting the flow.

FWIW, If you plan on using UV to control parasites such as marine Ich, a flow rate of about 120 gph is approximately what you need through the UV.

Which pump are you using?
I have a Sicce Silent 5.0 on my 75 gal system and I get around about 250 gph if I open up all the flow restrictions. I have it dialled down to 120gph through the UV.