Hi. I have a Hayward sand filter on my pool and currently the pressure gauge is reading over 50PSI when turned on. I have backwashed and the pressure does not drop. When I turn the filter off, the pressure only drops to 30PSI, not 0. I can also hear a gurgling or some type of sound at the top of the filter when it is turned off. And when I turn it on, there is water running down the filter. Do I need to change my sand? Or do I need to replace the gauge since it is going all the way to 0? The gurgling and water running down concern me that sand is causing pressure build up and needs to be removed/replaced. We have had our pool around 3 years and keep it open year round as it is enclosed. Our equipment is in an enclosed pump house. Normally we keep the pump/filter running all the time when it is cold, but it did drop down below 30 degrees suddenly and I forgot to leave the pump/filter running. Water is still coming out of the jets, so I don't think there is a freezing problem, but just wanting to make sure there isn't frozen sand inside the filter causing pressure build up.
Any advice/suggestions would be greatly appreciated. We try to swim everyday as I use it for therapy for health problems.