Center Pipe in sand filter breaking

[Poconos]

Sure looks like freeze damage but still don't understand why it didn't show up immediately and also why it was damaged in the first place. If it wasn't drained completely then the damage at the bottom could be explained, partially, but the top????? I really can't think of any scenario that would cause this.

Anyone else with ideas?

Al

[CarlD]

What size pump do you have? Your filter is a 150lb sand filter. If your pump is too big it could damage your filter.

Let's rule that out as a cause first.

[shalym]

It's a 1 hp pump--same as I've had since we got the pool 10 years ago.

Shari

[Poconos]

More long shots. When you replaced the sand did you partially fill the tank with water first, before adding the sand? This is done to let the sand evenly fill the tank without stressing any of the internal plumbing. After you filled the tank with sand did the center pipe stay centered so you didn't have to stress it to mate with the valve assembly? As I said, log shots but I have to mention them. I'm heading in the direction of anything putting stress on that center pipe. On the pump, even if it was way oversized I don't see that causing the problems you describe. I'm still stumped.
Al

[shalym]

More long shots. When you replaced the sand did you partially fill the tank with water first, before adding the sand? This is done to let the sand evenly fill the tank without stressing any of the internal plumbing. After you filled the tank with sand did the center pipe stay centered so you didn't have to stress it to mate with the valve assembly? As I said, log shots but I have to mention them. I'm heading in the direction of anything putting stress on that center pipe. On the pump, even if it was way oversized I don't see that causing the problems you describe. I'm still stumped.
Al

We did partially fill the tank with water first. I don't remember having to force the pipe into "mating" with the valve assembly, but we may have had to. I'll ask the people who were helping me do it. I did remember one thing--both times, it happened right after I had backwashed the filter because the pressure got too high. The backwashing went fine, the rinsing went fine, and when I put it back on the filter setting there was a kind of shudder when I turned the pump back on, and sand started pouring out of the return.

I am watching the pressure really carefully now and making sure it doesn't get too high--I'm probably backwashing too often, now--I do it if the pressure rises much over 5 from what it is when the filter is clean.

Shari

[Poconos]

Backwashing at a 5 psi rise is fine. In fact I do mine less than that unless I'm vacuuming a lot of junk. There is truth to the idea that the crummier the sand gets the better it filters but if I want better filtration I throw some DE in the thing. As I said above I still can't imagine high pressure due to dirt causing the problem. Anyone else want to chime in here with any ideas no matter how bizarre they may be?
Al