We remodeled the pool 8 months ago. At that time, we added a Triton II TR140 sand filter. It has gravel in the bottom with sand of top. I've only had to backwash the filter twice. The first time was fine but after the second backwash, I found gravel and sand in the pool, more gravel than sand.
I back washed for a total of about 5 minutes. During this time, the flow at the P-trap slowed down after about 3-4 minutes. It didn't pick up again. I rinsed for about a minutes and then back to filter mode. When starting in filter mode, I could hear crackling in the pipe (gravel).
As I haven't seen this prior to the back wash, and it stopped dumping gravel and sand in the pool after the first day, what should I expect? Is this s one time occurrence, are the laterals cracked, or could the back wash flow be too high? I did back wash on the highest speed (3410 RPM) using a Pentair VS pump.
I appreciate any help you may have.