These blogs are awesome by the way. I have been a silent reader for quite a few months now. We have an IG FG 18,000 gallon pool. Brand new equipment:
Pentair Whisperflow 1 hp 2 speed pump
Triton 60 Sand Filter
2 return lines
2 main drains
Initially when the pool guy set up our system, it was working beautifully for 15 minutes. Then a huge sand dump into the pool. Manufacturers defect on the Sand Filter, and we now have a new one.
Since the replacement, whenever we turn on the pool, open the valves, our pressure is at 17-18. When I add the vacuum, the pressure drops down to 10, sometimes 5. The pressure is not enough to vacuum. There is no air in the return lines. When I backwash the pressure goes back up (I know, backwards). I then start the process again hoping a simple fix will come to me. Our pool guy checked for leaks in the above ground pipes, debris in the pump, nothing. He is stumped. He said it wouldn't hurt his feelings if I hit the blogs. Here I am.
There is only 250 lbs. of sand in the filter. The idea was to vacuum the sand from the pool and catch it in the filter. This isn't happening because the vacuum is not working. Not sure if this affects the pressure. Any ideas would be appreciated!