How Do I Backwash My Diatomaceous Earth Pool Filter?

by Pool Builders on 05-07-2011 in Articles

A diatomaceous earth filter should be backwashed at least every three weeks. Proper backwash procedure is as follows:

Turn pump off. Put valve in backwash mode. (If you have a push/pull valve, backwash is in the up position.) If you have a flexible backwash hose attached, unroll and direct to the desired area. Turn pump on and allow to run for at least 30 seconds, or until water is clear. Turn pump off. Return valve to filter mode or rinse mode. (If you have push/pull valve, filter mode is in the down position.) Turn pump on and allow to run for 15 seconds. Repeat these steps at least three times, and more if water still is not clear. Don't forget to recharge your filter with the proper amount of diatomaceous earth. For your convenience, I have listed quantities of diatomaceous earth which should be added.

24 square feet filter, use 3 lbs. diatomaceous earth
36 square feet filter, use 5 lbs. diatomaceous earth
48 square feet filter, use 6 lbs. diatomaceous earth
60 square feet filter, use 7 lbs. diatomaceous earth
72 square feet filter, use 8 lbs. diatomaceous earth

Backwashing regularly will extend the life of your filter components. But even still, every six months, filter should be opened up and disassembled for a more thorough clean. Do not rely only on reading changes on filter pressure gauge. While cleaning grids, check carefully for torn fabric, broken ribs, and cracked necks. Also check that the standpipe o-ring is still in place. Make sure there are no cracks in filter manifold. Replace any damaged parts to avoid having diatomaceous earth returning to your pool. At times, you may run into problems re-assembling filter assembly.

The purpose of backwashing is to wash out the old DE, with its trapped impurities (dirt and grime) so you can replace it with clean DE. So why do you need to clean the DE filter? When you see a filter assembly that has not been cleaned in ages, the answer is obvious.

The problem is that impurities cake DE, the combination of DE with those impurities makes a thick, muddy paste that doesn't just "wash out" when you backwash. Over time, especially with repeated cleanups of algae infestations, or even a single cleanup of a terrible algae infestation, huge chunks of such thick, muddy paste clog the spaces between adjacent grids, and become thoroughly stuck, unable to be backwashed out. In these situations it is usually easier to buy new grids rather than waste your time trying to wash off this nasty 'paste'.

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