Measuring Flow

T-J · Dec 28, 2020

I’m planning on purchasing a Lifegard 25 Pro Max UV, along with some Apex flow sensors for both the UV and my media reactor. Both the reactor and UV will be off the same pump with a line split and gate valves to dial in flow.
My question is, do I put the flow sensor before each device (input side) or after them (output side)?
Also, if you have a pump suggestion, I’ll take that too!

Ron Reefman · Dec 28, 2020

Maybe questions about the Apex flow sensor placement would be better asked in their sponsor forum? Get it from the horse's mouth so to speak.

T-J · Dec 28, 2020

Ron Reefman said:
Maybe questions about the Apex flow sensor placement would be better asked in their sponsor forum? Get it from the horse's mouth so to speak.

Honestly, the question is more about where to put a flow sensor (input side or output side). The sensors just happen to be Apex for my build.

92Miata · Dec 28, 2020

T-J said:
Honestly, the question is more about where to put a flow sensor (input side or output side). The sensors just happen to be Apex for my build.

In theory - it shouldn't matter. There can't be more/less water going into the UV unit than there is coming out of it unless its leaking.

In practice - whether or not the sensor gets a correct reading depends on a lot of things and you should ask the manufacturer of the sensor.

garbled · Dec 28, 2020

I'd say it doesn't matter either way. Whatever fits your plumbing better. I seem to recall the FMM likes to be mounted horizontally if possible. The one thing that does impact readings slightly is if there is any air mixed in with the water, but presumably that won't be an issue with your UV.

Saltyanimals · Jan 14, 2021

Is there an alternative to the FMM? Read some not so positive feedback on it with accuracy and overall buggy. Is that the only game in town?

reddogf5 · Jan 14, 2021

For flow meters in general, you want non-turbulent flow going through them, which usually is translated into a certain number of straight pipe diameters before and after, typically 10 to 20, depending on the obstruction. Straight before is more important than after.