IMG_0275.jpgI have the pool for 13 yrs now and have done all of the maintenance required. The Power-Flo Matrix motor was replaced two years ago. The Strainer housing, cap, and thru-wall skimmer were all replaced this year. The union was also replaced as well. I am not seeing any visible leaks and have used plumbers tape for each connection. When I open the cap of the strainer housing, it fills and will start to overflow within seconds. Once I close the cap (that has been lubed and has a new O-ring) and start the filter, the water drops halfway down and stays there. I keep reading that there is an air leak on all of the similar posts. But, I am not seeing bubbles coming into the pool. I've also done the small plastic bag test to see if there's a block from the thru-wall skimmer to the strainer housing, and there isn't. The bag appears in there within a couple of seconds. Now even though the skimmer housing is about half full, the pressure from the filter return is great, not as good as previous years, but still great considering. When I go to vacuum, there is no pressure there at all. I called up Hayward to speak with a troubleshooting rep, they believe it's a plugged up filter since it is a DE. They recommended getting Alum and waiting overnight with that in the pool and then vacuum with the backwash drain open. Does anyone have any recommendations? Have you tried Alum? The pool was completely green and had scum and now is crystal clear with some dark algae spots on the floor of it. The only thing is, the pump had the issue as soon as I plugged it in, not after filtering for hours.