UV sizing for 200g

[Grasshopper04]

Based upon some sizing info from retailers, I just purchased and received a 40w UV sterilizer. I have a 200g display tank with 70g sump, with a decent amount of LR. The sizing guidance on the UV retailer's site recommended 967GPH. However, the manual which came with the UV unit has a sizing chart and commentary which doesn't seem to match with what was on the retailer's site.

My preference would be to plumb it through my single return pump, which at max output and 4' head will output 2,000 GPH. That seems like it's pushing the limit of the recommendation without "destroying the planktonic food supply for the reef". Is that really a concern? Do I need to consider returning it and getting a 25w unit? Buy a new return pump?

 

[C_AWOL]

It's of minimal concern. Most pods will typically populate areas that would not result in them passing through your uv and at a higher gph, the dwell time likely isn't long enough to cause them problems either.

 

[Grasshopper04]

If the tank can handle a slightly higher dwell time, that would be great because ich managed to make it into the DT, hoping to manage it.

 

[DrkNMighty]

There are generally two recommended flow rates. One is for algae/bacteria control and is a higher rate than the one that is for Protozoa bacteria (like ich) and is normally the slower rate. Ich generally requires a long dwell time.

 

[Grasshopper04]

So alternately I can run my 2,000GPG return through one discharge, and plumb a 650GPH return though the second discharge. Would that be preferable?

Assuming I’d rather not run two different UV loops if I can avoid it.

 

[DrkNMighty]

Are you saying your tank has two lines where water is returned from the sump to the display? If so, yes I don’t see any issue with adding a second slower return pump that runs through the UV and to the display while your other return pump goes straight from sump to display.

 

[Grasshopper04]

Currently the one 2,000 GPH return pump plumbs to a tee which returns equally to two separate DT returns. I’d prefer to keep a single return pump, running though the UV. If necessary, I can add a second return pump and split flow, one to left (with UV) and one to the right. I’d rather not run two different UVs at different flow rates, unless someone thinks it’s really worth it.

 

[C_AWOL]

Just to attempt to answer your question as best I can since I'm not entirely sure what you're asking at this point.

If your goal is to attempt to kill ich, a slower flow to generate a longer dwell time is ideal (in my opinion it ultimately won't do anything for that since not all the water will pass through but that's besides the point)

If your goal is to kill free floating algae/bacterial blooms then just about any flow will work including higher flow.

If your goal is to do both with 1 unit then ideally running it at a lower flow will bring you closer to your desired result without having to employ 2 units and 2 pumps (keep in mind your actual gph will likely not be 2000gph after all the bends and head pressure unless your pump is very strong + you can always plumb a manifold for the UV + a regular return)

Hopefully this clearly answers your question.