Sorry to be such a pain tonight, but I suddenly don't trust ANYTHING I've been told before finding this board!

Ok, for the past 4 years, whenever I needed to clean my cartridge filters (there are 4 of them), I have purchased a bottle of filter cleaner/degreaser and put them inside a clean 30gal. garbage can (purchased just for this use!), filled it with water (and the cleaner) and let them soak overnight. Then I would spend a couple of hours thoroughly spraying them out the next day.

I was told by a friend who has the same kind of cartridge filter that I could use muriatic acid to clean the filters by soaking them overnight with 1 gallon of acid to 29 gallons of water (in other words, same as before, but using a bottle of muriatic acid instead of the filter cleaner/degreaser.)
What do you think of this advice???
I have NOT tried this yet, but my friend SWEARS by it and has always done this (he has owned his pool for 4 years also). He has had no trouble with his cartridges.
Is there any reason(s) to do or NOT DO this???
Just looking for a little more experience and guidance here... I sure appreciate all the help I have already been given!
Thanks in advance,