Air binding in sand filter.

[psteichen]

I have an above ground pool with a single skimmer which feeds into my pump and then a Sta-Rite sand filter. My problem is that when air gets sucked into the skimmer due to floating toys blocking it, the kids messing with the door flap, or maybe just intense splashing near the skimmer, the air builds up in the sand filter. This in turn causes air binding (as described in the priming videos) which prevents the pump from priming until I let some of the air out through the waste port.

So my question is: Don't sand filters have any automatic way to deal with air? The top down filtration design of a sand filter seems to be a natural trap for air. I would think that over time even small amounts of air would build up into a huge slug of air in the top of the filter. Should my filter deal with this somehow that I don't understand, or do I need some DIY engineering to fix this issue?

 

[jblizzle]

Most filters have an air release valve on the top by the pressure gauge. You just open that to let the air out until water shoots out.
The only filters that do not have this release valve are the sand filters with the multi-valve on the top and in this case the air should be pushed out to the pool.

 

[psteichen]

How does the air get out of the sand filter? Pushed down through the sand with the water, or does the multi-valve handle this somehow?

 

[jblizzle]

The air certainly does not go down through the sand. I am not sure how the valve allows it to pass.

 

[ranger_ric]

I have a sand filter with the multi port valve on top. Mine does have a little valve to release air from the top of the filter. Just for grins I googled the StaRite Cristal clear 200# filter and found that the spec sheets states that it has a continuous air relief valve. You should probably dig out that owners manual or google your specific model of valve and see what it has for air relief. I have an Intex pool that I added a large filter and pump to. I open the air relief valve maybe once a week but I never have any air in my filter.
Since you can tie this problem to specific activities (splashing, kids playing with door, etc) perhaps you could just turn off your pump during those activities.

 

[JasonLion]

Most filters with a multi-port valve mounted directly on top vent air automatically when backwashing. Some also vent air when in filter mode, but that is less common.

Filters without a multi-port valve on top almost always have a manual air vent that you need to open to vent air and then close to prevent water from coming out.