# Thread: Cost analysis to decide when to backwash DE filter

1. ## Cost analysis to decide when to backwash DE filter

Split by moderator from the DE Filter Cleaning Tutorial to keep the Sticky clean. jblizzle

I did a cost-benefit analysis to tell me when to backwash/clean my filter, but this can only be done if one has a variable speed motor which displays the running wattage being used. Given my electrical costs per kilowatt hour from my monthly bill, knowing that with a clean filter my motor runs at about 300 watts per hour, and that DE costs about \$5.00 each time, I calculated that it was cost-effective to backwash/clean my filter when the motor speed increased to 344 watts per hour. If I waited longer than this, the excess monthly electrical costs would exceed the cost of the DE.

2. ## Re: DE Filter Cleaning Tutorial

I'm not a pool guy, but I think part of the reason to backwash is to avoid over pressure in the piping between the pump and the filter. I think it might stress out the weak points and maybe the motor. So you might have to figure the cost of fixing something breaking into the cost-benefit analysis. I didn't realize this for a while, but do believe it's true.

Originally Posted by tonto
I did a cost-benefit analysis to tell me when to backwash/clean my filter, but this can only be done if one has a variable speed motor which displays the running wattage being used. Given my electrical costs per kilowatt hour from my monthly bill, knowing that with a clean filter my motor runs at about 300 watts per hour, and that DE costs about \$5.00 each time, I calculated that it was cost-effective to backwash/clean my filter when the motor speed increased to 344 watts per hour. If I waited longer than this, the excess monthly electrical costs would exceed the cost of the DE.

3. ## Re: DE Filter Cleaning Tutorial

The pool pump can not generate enough pressure to damage the pipe. It can only do about 40psi.

4. ## Re: DE Filter Cleaning Tutorial

On mine, I have saddle clamps for the chlorinator line, and I think 40 psi may be too much for it. I'm not sure how much pressure it would take to screw up the valve system either, or possibly the DE filter panels which probably feel that pressure to some degree (and can be somewhat fragile). I think long term, it stresses the system, but I'm not a pool guy.

Originally Posted by jblizzle
The pool pump can not generate enough pressure to damage the pipe. It can only do about 40psi.

5. ## Re: DE Filter Cleaning Tutorial

Pool equipment is designed for 50psi at a minimum.

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