Johnny,
Welcome to the Forum.
I can understand the motor burning out if you added 6lbs of DE after backwashing each time. You need to check the procedure for backwashing The DE 4820. If you don't have it, this is what I do when I backwash my DE 3600.
Stop the puimp. Set the multiway valve to the filter in the backwash positin.
Open the main drain as well if you have one. You need to maximise flow when backwashing.
Start the pump, and look at the glass on the waste connection. It will turn dirty/white. When it is clear shut the pump off.
Switch the multiway valve back to filter, and start the pump. Filter for about 3 - 4 minutes. Then stop the pump.
Switch the multiway valve to backwash, and start the pump. Check for more DE in the sightglass, and when clear shut the pump down.
Continue these steps until the sightglass is clear. Shut the pump down and switch to rinse on the multiway valve. Start the pump and rinse for about 3 minutes. Then stop the pump.
Switch back to filter, start the pump, check the pressure on the filter, and at this point you can add the DE slowly through a skimmer, 1lb. at a time. There is no need to premix, but you have the option.
I would continue to use DE instead of Aqua Perl.
Hope this helps.
Pat
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