Of course, this debate goes on forever about sand. It makes sense to me to NEVER replace your sand but simply take care of it. I believe sometimes we over-think what makes a good filter medium:
1. Dirty sand filters better..........hmmmm. maybe, but how dirty? If you believe that verbatim then you will never backwash 'til your filter explodes from running 200psi and filtering no water (I'm kidding...it won't do that but I'm making a point.....you certainly can't let it get too dirty so how much is enough?)
2. New sand has sharp edges and, as a result, catches more dirt......hmmm, maybe, again. Until I see some new sand and then 10 y/o sand under a microscope, I'm not sure the sand gets that much wear and tear.
Even if it's true, couldn't you make the argument that the old, smooth sand fits together more tightly creating smaller spaces for the water to pass through and, thereby, catching more dirt?
Different brands of sand would certainly have different characteristics....I believe the only criterium to be called "pool" sand is the the particles be in between some size values but itr doesn't say what percaentage of those particles can be smaller or larger.
Until my filter starts spitting dirt back into the pool, I'm gonna keep this sand forever. BTW, Vince, if your sand has channeled, simpy open the top of the filter and break it up. Backwash thoroughly, and you're good to go for another season.
I've often felt that channeling is a possible sign of an overdriven filter, i.e. the pump pushes the water thru the filter with too much force but contaminates in the sand could also be a culprit.
From what I've read here and my personal experience, I'm pretty convinced that a big, big filter will solve most of these issues. Whether that filter is cartridge, DE, or sand bigger is simply better in virtually every case.