Triton 2 Sand Filter turns off, all of the water dumps back into the pool

[JShope]

I don't have a backflow preventer on the filter pump line, but I've never had this problem before. As soon as the pump turns off, all of the water in the filter runs backward through the pump and into the pool. It is so quick and forceful that it will flip the skimmer basket over and force a lot of water onto the deck.

I have not replaced the backwash valves in the 12 years I have been using them, but it is not a matter of running down the wrong pipes. I also don't have any problems running the filter so I don't suspect the laterals.

Does the Pentair Triton ii have any built in backflow preventer, or should I just fix the symptom and add one?

[Denniswiseman]

I had the same problem, it was a build up of air in the filter which compresses (air compresses and water doesn't) and forces the water back under pressure. My skimmer lid blew off as well
If it doesn't cure a non return valve will prevent further problems

[dr_harika]

How did you solve the issue Denniswiseman? How did you get the air our of the filter (assuming it is a sand filter?). I too have this issue.

[Denniswiseman]

It cleared up by itself after a long period running
Some filters have an air release valve to let air out
I do believe there is a small pipe inside the filter which vents into the returns to expel the air
A suction side air leak could cause air to be introduced into the system, does air come out of the returns?

[JShope]

I have noticed that the new lid and seal for my pump still leaks air and water. It makes a lot of sense that it pressurizes in the filter. The filter does have an air release valve (manual operation) and a special tube and filter that is designed to pull air out of the system. It might be building up faster than the little tube can handle.

[Denniswiseman]

Very likely
Have you smeared silicon grease on the new "O" ring as that is the most obvious unless you have a suction side air leak

[JShope]

I greased up the o-ring and even the threads of the pump, and it looks airtight. I'm afraid I might have a broken pipe. The ground is wet around the pump, which I assumed was from the leaky lid. But, it's not leaking now.

[Denniswiseman]

It maybe the pump shaft ceramic seal in the pump
There is a small hole in the bottom of the pump that lets water drain out
There are plenty of YouTube videos to follow