Changing Sand in Sand Filters
INTRODUCTION
The sand in sand filters in pools needs to be replaced every three to five years in pools that use chlorine or bromine as the primary sanitizer. If it has been longer than one year since the filter media has been chemically cleaned, it may be necessary to replace the sand. Use Kleen It® before closing the pool in the fall and Strip Kwik® midway through the summer to help keep the sand in good condition.
Replace the sand more often if you have hard water — which can make the sand channel. Also replace more often if you have problems with cottonwood seeds or anything else that might cut filter efficiency.
For biguanide systems, like SoftSwim®, it is recommended that the sand be changed every season and the filter be chemically cleaned with SoftSwim Filter Cleaner® every four to six weeks.
To change the sand in sand filters, do the following:
STEP 1: Check with owner’s manual as to how to open the filter. There are several types of filters and each one differs as to the fill method and amount of sand.
STEP 2: The formula for figuring the amount of sand needed is as follows:
82 pounds of sand per cubic foot of filter area
There should be a tag on the filter tank stating the cubic feet. Example: a 3.1 cubic foot filter would take 250 pounds of grade 20 Silica sand.
If you do not know how many cubic feet you need, fill to approximately 2/3’s full or if you know the model number, see the chart on the last page.
STEP 3: The best way to remove the old sand from your filter tank is to use a wet/dry vacuum or you can remove it by hand.
STEP 4: Check laterals for cracks or clogged screens (the screen located on the underneath side of the laterals). If the lateral is damaged or has a hairline crack, replace. Please note filter brand and model number when checking on replacement part(s).
STEP 5: Before adding new sand to the filter, cover the standpipe with a rag to prevent the sand from going into the standpipe and clean sand out from the lateral hub guide at the bottom of the filter tank.
STEP 6: Fill the tank with water to six inches above the laterals. Water helps protect the laterals from damage due to the weight of the sand. Then slowly add enough sand to cover the laterals. Finish filling with the proper amount of sand. Silica sand, grade 20 is highly recommended by most filter manufacturers. Beware of inexpensive filter sand. Round river sand gives poor filtration.
STEP 7: Lube the tank o-ring and all other o-rings with Magic Lube or a type of teflon based lubricant/sealant. Do not use Vaseline or petroleum based lubricant/sealant because they are water soluble and will not last as a sealant and will cause plastic to breakdown.
STEP 8: If you had to cut pipes going to and from the filter, use no-hub clamps or unions in lieu of pvc couplings. This allows for easier access in the future.
STEP 9: Close filter and backwash for 3-5 minutes before turning the valve to filter position. Always shut pump off before turning valve position.
Download a printable PDF: BUL-140 – CHANGING SAND IN SAND FILTERS
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Bulletin #130