Backwashing, or Cleaning the Filter
By Merry Wise – Cruising Through Pool Care The Wise Way
Periodically, the pool filter or spa filter will need to be backwashed, and/or cleaned. Backwashing essentially reverses the water flow and flushes out the pool filter, internally cleaning it and readying it to function efficiently again.
How you do this depends on the type of pool filter you have, so we will discuss the most common three kinds you will usually find on modern pools and spas.
There is one type that is not meant to be backwashed and we will describe how to clean those.There are also a couple of oldies out there and your pool might be equipped with those that have to be handled with a series of rather complicated steps to keep functional. Some of those never did work very well even when they were new, and my advice would be to replace those with a more modern up-to-date and properly sized pool filter system as soon as possible.
A sand filter contains laterals, finger-like thingys, at the bottom and a combination of filter sand or sand and small gravel called chat that filters the water as it is forced through it. It should usually be backwashed weekly, or when the pressure gauge on the top rises about 8-10 points, usually over 25 psi.PSI stands for “pounds per square inch”. Prior to starting to backwash either of the two types of pool filters that require backwashing, start water running into the pool to replace the water you will be cleaning out, using the fill valve to turn it on or a garden hose. Water should always be kept at about the middle of the skimmer opening or title line. To backwash a sand filter, first turn the pool pump off. Then, turn the valve to the “backwash” position, and turn the pool back on. Backwash, which means to reverse the flow of water to clean the filter, until the water looks fairly clear in the sight glass, a little glass window bulb water will be churning through on top of the filter or on the backwash valve. It will take about 3-4 minutes or so. Then, turn the pump off again, and change the valve back to filter.