Yep, I believed that too, until I saw an electron microscope picture of freshly cleaned 10 year old sand from a commercial filter that had just as many points as the fresh sample next to it. It can become rounder and smoother with alginate biofilm build up but that was removed in the commercial washing process (acid clean and air scour plus wash with a cleaner)Heckpools said:The sand in your filter is like a rock in a moving river. Over time the pointy edges become rounded from the constant water flowing over it. The more rounded the edges get, then less it filters out the tiny particles.
my personal opinion is every 3-5 seasons. 3 for those who run the filters non stop and 5 for those who run the filter 8-10hrs daily.
Thats just my opinion though...
kplaster said:How often should this be changed ,4th summer of use!!!!
I don't quite agree with that, it does become sticky and pebble into balls which allows channels to develop. So a good clean is necessary from time to time but changing it, waste of money unless there is a problem (calcium biuld up etc) or you are changing for something possibly better like Drydens AFM which I am experimenting with.kplaster said:If it ain't broke don't mess with it...I haven't had any problems just was wondering if I should do it..Thank's for all the advice!!!