Sand blowing into pool from the filter

[philc]

I have a Doughboy Silica II filter. It recently started "blowing" sand back into the pool when the pump is restarted. Each time the pump is turned on a couple of handfuls of sand is blown back into the pool. It then stops, until the next time the pump is cycled. I know that other posters have been told that a "lateral" might be broken. Does the doughboy have "laterals"?
Thanks for any help, in advance.

 

[woodyp]

If it's a sand filter, it has laterals as far as I know.

 

[philc]

The internals for a doughboy silica II. If it has laterals, where would I find them?

 

[dakhath]

Taken directly from Doughboy's website: The tank’s Single-Part Underdrain Assembly assures maximum longevity because this unique design has no laterals which can break off.
http://www.doughboy-pools.com/Products/PumpsFilters/Silica.aspx

Part #25 on your diagram is the "Periphery Underdrain Assembly" the doughboy's equivalent of everyone else's laterals.

I pulled this from the manual under the troubleshooting section.
http://www.doughboy-pools.com/servicesupport/images/documentsearch/og99silica2.pdf

G. Filter is backwashing when valve handle is in FILTER position after servicing filter.
1. Valve cover is assembled backwards on tankcover (180o from correct position).

By any chance did you recently open up the filter to look inside? Could this have possibly happened?

 

[philc]

Nope, I have not opened it up except to put the sand inside by removing the bolts around the tank's "equator". I wonder if the "spider gasket" has begun to leak?

 

[dakhath]

That's what I'm thinking too. The spider gasket seems to be the common culprit right after broken laterals.

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