Interesting. I had a similar issue. My PB pressured tested with air at 25 PSI, it held for 3-4 weeks with slow decline of 3 PSI each day. Then they were putting in some trenches and cracked one of the plumbing pipes. They fixed it and pressured it back to 25 PSI and it lasted for only 6 days until it was at 2 PSI. I told the PB that I was concerned and it said that the industry norm is usually no leaks for the 30 minutes and that the leaks could come from around fittings on the heat pump, SWG, and water filter pump that may have small leaks (which is okay?) and allow some air to leak. The PB said that you can't ever get a complete sealed system. Before the deck is laid, I plan to ask him to pressure test it again. I understand that the environmental temperature may play some affect, but what do others think about how long should the PSI stay stable (or what average interval of PSI decline per day should be seen) for water or air pressure testing?