1. Pentair T29 Fluidmaster Valve Manual
2. Letro Automatic Filler Owners Manual
3. Pentair Autofill Installation

I had the pool re-plumbed and re-plastered in 2009. At that time they put in an automatic filler (mechanical float type).I'm not certain that the thing ever completely shuts off. I'd hear a little high-pitched whine sometimes when it was near shutting off. It just seems there might be a little trickle into my large body of water.My problem is that the water department determines you have a leak if they see the little dial spinning on your water meter when they come by to look at it. I've told them in the past that I have a pool auto filler and that water may be flowing because of it. If I turn off the pool auto fill, the little dial stops spinning (and it's spinning very slowly).In the past, the water department has been okay with my explanation. Now, however, their conclusion is that if the auto fill doesn't shut off that I have a leak in my pool that needs to be fixed.

They said they've talked to pool contractors and they've been told the auto fill is supposed to shut off completely. I tried adjusting my auto fill float. I no longer hear the high-pitched squeal. My water level has gone down a little bit from adjusting the float, which I suppose can be expected. It still seems like it may not shut off completely. We're starting to look at the water meter a few times during the day to see what's happening.Should I expect it's going to completely shut off?I've already been fined for not repairing my alleged leak.

I got them to waive it this time, but they will be back and if they see the water meter dial spinning at all, I'll get my fine reinstated. My pool surface area is probably around 580 sq. Ft.My problem is that the water department has been educated by pool professionals who say auto fills should shut off. Therefore, I'm in violation and I'll keep getting fined with increasingly-large fines for repeat offenses unless I can get it to shut off.

Pentair T29 Fluidmaster Valve Manual

So far they've been nice. I don't know if I can educate them differently.How can I calculate the expected water loss from evaporation?

Letro Automatic Filler Owners Manual

I've also been using Heatsaver Liquid Heating Solar Blanket. It's supposed to help keep in heat and reduce evaporation. I don't know what difference that makes (in the real world or in calculations).I assume we shouldn't be using the pool when doing a test; otherwise we'll have water loss from pool use.

Pentair Autofill Installation

How many days do we need to not use the pool for a proper evaporation vs. (it's summer and we're swimming)Thanks again for the help.