Where to place FMK on UV

[thewalkingdad]

Hi all,

I have a UV sterilizer for my new build. I will also have an FMK. I want to tune the UV to cover algae/bacteria and will need to dial in flow, hence the FMK.

Where would you install the FMK to get the most accurate reading, pre-UV sterilizer or post-UV sterilizer? Does it matter? What if you have to step-up or step-down the pipe diameter to accommodate the FMK. Where would you install it in that situation?

 

[ReefHog]

Place it right after the UV for most accurate flow reading. My UV is 1 inch. I have 1inch reducers before and after to accommodate my return piping.

 

[thewalkingdad]

Thanks Hog. I have 1 1/2" return pipes and the sterilizer is the same. But my return pump is 1" so I'll need a step-up pipe.

 

[ReefHog]

Thanks Hog. I have 1 1/2" return pipes and the sterilizer is the same. But my return pump is 1" so I'll need a step-up pipe.

Won’t be a problem. Just make sure UV exit is above UV supply so no air pockets get trapped in UV.

 

[thewalkingdad]

It will be completely vertical. Although, that will mean I need to induce a few 90* bends since the in/outlet are perpendicular to the sterilizer itself.

 

[ca1ore]

Doesn’t really matter where you put the flow meter, though if memory serves Neptune recommends it be a foot or so from the pump. I’d put it where it is most easily serviced since they do clog up over time. 1” flow meter is quite restrictive. I use the 2” on my main return.

 

[Malcontent]

If it's a recirculating system, time-dose reciprocity means almost any flow rate will be equally effective as long as it's not too low.

 

[SPR1968]

Thanks Hog. I have 1 1/2" return pipes and the sterilizer is the same. But my return pump is 1" so I'll need a step-up pipe.

I would maybe look to using the 2 inch flow sensor on that size pipe, that’s what I did on my 1 1/4 return pipe anyway, as I didn’t want to restrict flow

it is a big beast though by the time you get the adapters and fittings into it to get up to that size..

I placed my flow sensor off the manifold and ‘into’ the UVC and it gives an idea of the flow through it. It’s also in easy reach for any maintenance

just consider adding unions each side of the flow sensor for easy removal.

 

[thewalkingdad]

I would prefer to 2" but it's just more money!!!

I'll likely end up picking up the 2" though.

 

[ReefHog]

just consider adding unions each side of the flow sensor for easy removal.

Neptune Flow sensors come with unions.

 

[lakai]

just buy a cheap $10 one from amazon and solder a plug on it to make your own.