Discount Pool Supplies and Spa Supplies

Short filter cycles between cleanings

Insufficient backwashing time

For the most part, 2 to 3 minutes is enough. This should be done until the water runs clear. A sight glass will help you determine the correct backwashing period. Cycling the pump on and off two or three times when backwashing often helps to eliminate additional waste.

Water not properly balanced

Check the chemical balance of the pool water. An excessively high pH can cause calcification; a low chlorine residual encourages algae growth, which can clog the sand bed. Bring the water into balance. Be sure to check and adjust the total alkalinity and water hardness levels. Replace the sand, if necessary.

Inadequate flow

20 gpm per square foot of filter area is needed to properly backwash a sand filter. If less than 20 gpm per square foot is being delivered to the filter on both the filter and backwash cycles, a larger pump and/or piping should be installed.

Incorrect sand size or type

Too fine of a grade of sand will clog too quickly, If the sand is too soft it will break up and cause clogging as well. Replace it with the manufacturer's recommended sand size and type. Most manufacturers generally recommend No. 20 grade silica sand.

Filtration system improperly sized

The pump should cycle the pool volume in approximately 6 to 8 hours. A longer turnover rate means a shorter filter cycle. Use the manufacturer's sizing chart to determine the correct size of the filter and pump. Increase the filter and/or pump size, if necessary.

The water is cloudy.

Particles too small to be filtered

Under some conditions, alum may be used as a sand filter aid to remove fine particles. The pH should be adjusted to 7.0 to 7.4 to ensure proper flocculation of the alum on the filter bed. Application is 1 lb. alum per square foot of filter area. Use only as necessary and be certain to follow the instructions on the label. A water clarifier may also be used.

Water not balanced

A high pH or total alkalinity can cause scale deposits and cloudy water. Low chlorine residuals allows algae to grow and give a cloudy, green-or rust-colored tint to the water

Damaged or worn o-rings/gaskets

The "spider" gasket in the base of a multiport valve, or the o-rings or pucks in a push-pull piston type backwash valve, may need to be replaced. When these become worn or torn, water will bypass the filter and go directly back to the pool.

Improperly sized filter

An undersized filter is unable to keep up with the dirt and organic matter introduced into a pool. A residential pump/filter should be sized so as to turn over the pool volume in approximately 6 to 8 hours at the most. A commercial pool may require a shorter turnover rate. Make certain that the filter cycle is long enough.

Incorrect grade/size of sand

Too coarse a grade of sand allows fine particles to pass into the pool. Replace the sand with the proper grade. No. 20 grade silica is usually recommended. Consult your manual.

Sand is passing into the pool or out of the filter during the backwash cycle.

Damaged or worn o-rings/gaskets

The "spider" gasket in the base of a multiport valve, or the o-rings or pucks in a push-pull piston type backwash valve, may need to be replaced. When these become worn or torn, water will bypass the filter and go directly back to the pool.

Sand needs replacement

Sand that is too fine will pass through the underdrain or laterals. If the sand bed is channeled, high flow rates through the channeled area will break up the sand and allow it to return to the pool. Replace the sand with the type and size recommended by the filter manufacturer

Laterals broken or cracked

Replace damaged parts. Clean the filter tank/o'ring mating surfaces and lubricate the o-ring with a Teflon-based lubricant when reassembling.

Over-sized pump

An over-sized pump will break up sand particles which allows them to pass through the underdrain or laterals. Correct this