cleaning used ac300 filter

replace the foam and carbon and let the stuff thats removeable soak in bleach and put some water with a little bleach in the other part with the pump
 
If there's a lot of lime scale on it, you can also use vinegar to dissolve the deposits. Vinegar rinses away easily and is tough on calcium carbonate.
 
not bleach

I am not fond of bleach, too hard to get it off later. Oxiclean is as good for sterilizing and rinses off better.

I prefer to start with vinegar, then move to CLR for lime deposits. Use a new toothbrush to scrub impeller and filter body, get a filter brush set to clean tubings. Get new sponges and carbon.

Let everything dry in the sun before using.
 
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