WHAT TO CHECK IF DE POWDER APPEARS IN POOL

Question: We started seeing diatomaceous earth powder in our pool. We read that when you see this condition, there is probably a torn grid in the vertical grid filter. We took the filter apart but could not find anything wrong. The filter has been back in service for several days, but we still have powder in the pool. What is the problem?

Answer: Without knowing where the diatomaceous-earth material is ending up in your pool, we will look at a number of options that could be causing your problem and the costs to repair it.

Check the manifold O-ring. This small, thin rubber ring may not be providing a proper seal. The cost to change the ring should be less than $10.

Your pool's circulation system may have a suction leak on the pump. If this is the case, this is what happens. When the pump shuts off, air is drawn into the system, which forces DE powder out the main drains or skimmer.

After the system comes back on, some of the powder will be sucked back in and part of it may be left in the pool. Replacing the gasket on the pump should cost about $15.

Check to see whether the gasket in the multiport/selector valve has gone bad. This valve allows you to select where the backwash material will exit your filter. A break in this seal may allow the DE powder to exit the filter into your pool. The cost for a new gasket should be around $15.

Inspect the plastic nipples of each of the grids that fit into the manifold; one or more could be broken or cracked. Though the cloth material covering the grid may appear to be intact, the inside framing of the grid where the nipple is inserted into the manifold could be the source of your problem. One of the eight grids in the system would cost less than $20 if it needs replacement.

Inspect the entire manifold that holds the grids together for hairline cracks, which would allow extra DE powder into your pool. A new manifold should cost less than $50.

The worst-case scenario is that you would need to buy a replacement filter, which may cost about $550 uninstalled.

If you are tired of searching for the cause of the DE powder, a licensed and trained pool-service professional should be able to identify the problem for about $100. Additional charges to repair and install replacement parts will vary by area and pool-service company.

"Annual cleaning is the key to making the DE filter last and last. Every fourth week spend about five minutes to backwash the filter, reversing the water flow inside the filter to allow the waste DE to fall off the grids and wash out of the system," says Jackie Arnault of the Pool Pleaser in Orlando, a service and repair company.

Periodic inspection of all parts inside and out will allow you to spot small problems before they become big ones, says Arnault.

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