I am trying to figure out how to maintain an old (late 70's) pool. It has a big old Squimquip sand filter, and right next to that is another canister about a third of the size. The canister seems to be downstream of filter heading toward the pool. It's got a pressure seal but no pressure gauge. Inside is just a basket made of very fine cloth in which a quantity of fine silt has collected. I have not opened up the sand filter yet so I'm not sure if that stuff is sand that has escaped, plaster from the pool, or something else. Can anybody tell me what this thing is for and what I can do to help it do whatever it's supposed to do?

TIA

I have something very similar, but it is a DE filter and it is there to allow me to back flush without losing any water. The container collects the waste DE while allowing the water to either return to the pool or be sent to waste.

A photo will help. Do you have any valves after or just before this device?

The equipment is in a cramped little pool shack so it would be impossible to get an overall photo but maybe I can stitch one together. It looks like the plumbing goes POOL --> PUMP --> FILTER --> THIS CANISTER --> GAS HEATER (not in use) --> BOOSTER PUMP --> POOL

Booster Pump?

Yeah, for the pool cleaner.

May there have been a DE filter at one time? It sounds like a recovery tank for a DE system.

huh... maybe it is DE. I thought it was sand because it looks pretty much like this: http://ebookbrowse.com/high-rate-sand-f ... d286680821

I guess I need to do more googling.

So the function of that would be keep the DE from going to the pool, and you'd put whatever collected there back into the filter?

Post a picture of the filter label and we can help identify it. I don't have a recovery tank, but I think it collects the dirty DE so it can be disposed of properly when you backwash the filter. You don't want to put used DE back in your filter.