UV Flow Question

[Scottydo]

Question: We just installed a Pentair 18W UV with an inline Sicce 2.0 wet/dry pump running out of the water. We have a gate valve installed after pump and before UV inlet and a Neptune ½” flow sensor after the outlet. The piping is a mixture of ¾ flex and ½” hard pvc with a handful of bends and turns. We are only getting 115gph with the gate valve full open. The pump is rated up to 568 gph on the box specs. Our intent is to mainly run for Protozoa and Bacteria which requires 50GPH so for that we are ok and can dial it in but in the event we want to run for Algae at 25-300gph it doesn’t seem like we will be able to achieve the flow needed based on the current setup. Any suggestions? Should we buy a new pump? If so how much bigger? Are we doing something wrong? We are pretty new to this whole saltwater tank world, so any help is appreciated. Thank you.

 

[jassermd]

It's likely a combination of both the number of 90s, and the change in the diameter of the in/out lines as well as the pump size.
If you're looking to push more volume/flow, you'll need to either increase the size of the pump or the diameter of the lines or both. Max flow through 1/2 line w/ nominal pressure is between 420-840 gph, without head height loss.
<https://hy-techroofdrains.com/water-flow-through-a-pipe/>
FWIW, I run a COR15 w/ 3/4 lines on a 57w and flow max's out at 250-280 gph

 

[Reefpro]

So I’m just setting up my 57 watt as well from BRS. on a 300 gallon set up. The instructions are calls for crazy amount of flow do you know what the target flow rate is ?

 

[jassermd]

I have the same unit... I couldn't make any sense of the flow numbers that the manufacturer recommends. Ultra Aquaviolet notes that for saltwater use for parasite control is 1066 gph. Not sure how that is even possible given that the same unit (50w HO by Pentair) is 260-330 gph. Something isn't adding up... Plus, to get that amount of flow, you'd need 1 1/2 or 2 in lines and a powerful pump without anything else plumbed to it. Yeah it's probably possible, but not likely feasible.

I have mine running at 200 gph. I can't get the flow above 250-280 gph with a COR15, and that's if it's the only thing plumbed to it.

 

[Reefpro]

Yeah their 1066 makes no sense. Based of what I’m seeing I think it’s closer to the 550-600 range

 

[Uncle99]

At least 4-6 times volume for water column algae control.

 

[jassermd]

The set up is fairly simple... I run 2 return pumps, COR15 and COR20, each feeding one of the 2 returns in each of the overflows. I'd snap some pics, but I'm not at home...

The COR15 - Up pipe from the pump Ts to both right and left sides of the tank. On the left, the flow is through the UV and through the flow meter prior to going to the return line. On the right, straight shot to return and there is a ball valve that allows me to restrict the flow to the return line so as to balance the flow to the UV. Everything is 3/4 PVC or silicone tubing. Head height is about 6 ft from pump to top of tank.
If I shut off the flow to the right return, max flow I get at the UV flow meter is what I noted above.

 

[piranhaman00]

The differing flow rates is because there is no data on what UV dose is necessary to eradicate Protozoa in saltwater, there is data on true “ich” from freshwater but there is no “ich” parasite in saltwater so no one knows

Slower the better. I have been using UV a while in different ways, I find that even turning the tank over 1-2x per hour is fine for perfectly clear water. Using carbon helps to clear the water and allow better UV dosage.

 

[rhostam]

I came here to research what people are doing with their installs. I have a Pentair 40W that I just installed. It is mated to a COR15. There are four 90 elbows in the total flow path (in and out of UV), and I only see a peak of about 657 GPH. If I switch out the CO15 for the COR20 I'm using for return, I see less even at max (???). The Pentair documentation recommends upwards of 1000 GPH for my application (algae). If I can reach this flow, then I can tune down later for other applications.

I see a recommendation above of about 5-6 total water volume (mine tank being ~220 g). Pentair's number is roughly in line with that figure. Should aim for additional flow, or is 657 GPH adequate (but a "waste")?

I created a manifold to use with the UV. My goal was to feed two reactors with it.

CORxx 3/4" -->
Primary 3/4" tee --> one end proceeds to 1" barb to the UV, then 90 of the tee goes to another 3/4" tee -->
From this second 3/4" tee, each end terminates in a 3/4" elbow, which has a 1/2" reducer leading to the valved barbs.

This was the best arrangement I could devise for the space I have available in my sump.

Coming out of the top of the primary tee 1" barb is a hose which leads to a 1" reducer --> 1.5" elbow into the UV.

This was a post-install unit, so I have little space to work with, and it's why this isn't hard plumbed all of the ways through.

I can remove the manifold and just have CORxx 3/4" --> 1" barb and attach the hose directly. This is what I've done for the return. Thoughts on whether this would be worth the effort to increase flow? I know it will increase it, but not sure about the margin of improvement.

Thoughts on increasing flow/ experimenting with manifold removal?

A few pictures: