Thinking about adding an inline flow meter, worth the money

Started by Marcus Reed · · 3 replies
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#1
Been running my turnover and flow numbers off the Pentair affinity curves and my VS pump's wattage readout for years, basically backing into gpm instead of measuring it. Works fine for scheduling but it's still a guess once the filter starts loading up or a valve isn't dialed in exactly where I think it is. Looking at adding an inline paddlewheel style flow meter after the filter, mostly out of curiosity but also so I can actually verify turnover instead of assuming 22k gallons moved in X hours. Anyone running one long term on a residential pad. Worried about accuracy drift, fouling from salt, or it just being one more thing to maintain for data I don't strictly need. Curious if it changed how any of you actually run your pump schedule once you had real numbers instead of curve estimates.

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#2
Honestly with a spool I never bothered backing into gpm off curves at all, turnover math on 2500ish gallons versus your 22k is a totally different animal so take this with a grain of salt. But the part about curiosity being the main driver, that's the part I'd push back on a little, a meter that fouls or drifts on salt and needs its own upkeep is a bad trade if the number it gives you doesn't actually change what you do with the pump schedule. If dialing in your valve more precisely would genuinely shift your run times then sure, otherwise it's just another thing to babysit for a stat you already estimate close enough.
#3
I went down this exact road when I first wired up the WiFi pump controller, wanted real numbers instead of trusting the wattage curve, so I grabbed a cheap inline paddlewheel meter off Amazon just to see. Ran it about a season. Derek's point about it not changing your schedule is dead on in my case, the number was close enough to what the affinity curve said that it didn't move a single thing I actually do day to day. Where it did earn its keep was catching how much flow dropped as my filter loaded up between cleanings, that was more dramatic than I expected and the wattage readout alone didn't make it obvious. But I'm not salt so can't speak to fouling there, and honestly once I'd seen that pattern for a few months I stopped checking it. Still installed, just not something I look at unless I'm chasing a pressure complaint.
#4
Never ran a meter, cartridge filter so no backwash reference point to begin with, just pressure gauge and gut feel after five seasons. Robotvic's thing about the filter loading showing up on flow before it shows up on wattage, that tracks with what I see on pressure psi climbing slow over a couple weeks and I just rinse the cartridge when it hits a number I know by feel now. Don't need a paddlewheel to tell me that, the gauge already does it cheap and nothing to foul.

If your valve's actually mis-dialed enough to matter, pull it apart and check by hand once, don't need a permanent meter sitting there for that. Sounds like a solution looking for a problem unless you're chasing a specific turnover complaint from a tech or inspector.