Pre-gunite, pressure gauge dropping slightly ... concern?

[CMorrow]

Hi folks. We are set to have gunite this Friday. Plumbers were here today muscling the PVC to get it all back into the form -- some long stretches had slipped under the form and two corners had also been set outside the form. I was worried they wouldn't be encased in the gunite, so had PB call plumbers to fix. While they were here today, they were pushing around the PVC pretty good to get it inside the form. My question is when they set the PVC nearly 2 weeks ago, they tested the water pressure up to 35 PSI. Today, before plumbers got here, it was down to 33 and change. That seemed ok to me for 2 weeks considering evap. Granted, my pump's not running yet, but still. Now, after plumbers were here, gauge is reading close to 32. Is it possible they jostled some unions and created a small leak somewhere? Don't want to call PB for every little thing, but am concerned once gunite is shot, ain't no going back. Am i worried over nothing? A pound of pressure over a few hours?

 

[jblizzle]

The pipes are pressurized with air and not water.

Being that it is a closed system, the internal pressure will rise and fall with ambient temperature and sun exposure.

I would just keep an eye on it over the next day and if you find that it is lower tomorrow afternoon, call the builder before they shoot.

 

[blakeusa]

With a leak they normally would go to zero.

 

[CMorrow]

Thanks, to both of you. It is down to 31 now -- 11 pm. I'll keep my eye on it for sure. Question: if they pressure check it with air, why do my skimmers have water in them? I know the day they pressure checked, they asked for my garden hose...
Appreciate the time here. Too many things to remember while workers are on site. Also, trying to let them do their job without nitpicking over everything I don't understand. Steep learning curve for this one.

 

[SBall]

I pressure checked mine with water. I have had difficulty with the Jandy valves and also had difficulty fully plugging the return lines into the pool. Just little drops, but enough to lose pressure. Keep in mind that a pool plumbing system is also an "open" system in the sense that the lines are meant to hold water, not to contain pressurized water. There is certainly pressure in the system when the pump is running, but there are also the returns which act as outlets, and water follows the path of least resistance. I read somewhere that if the lines will hold 20 psi for 20 minutes you are good to go.