I have a (roughly) 20,000 gallon pool.  

pump: Pentair 342001 SuperFlo VS Variable Speed Pool Pump

filter: 48 SF Hayward DE filter.

Pipes are 1 1/2"

I think the grids in the filter are torn because it is pumping DE into the pool.  I'm aware that DE is technically the best, but I'm really leaning towards swapping it out with a sand filter because its good enough and is easier to maintain (in my experience, anyway).  So my question is: according to the above specs, what sand filter would be the best for me?  It is being suggested in a reddit thread that a 27" sand filter would be correct for me.  Does this sound correct?  I'm including pictures of the current setup, but, to be honest, I'm not sure that we have correctly a matched or paired pump/filter combo.  The people that built this system don't seem to know a whole lot about pools and the whole setup seems pretty patched together.  Thank you for your help.  

current filter specspump/filter