Swimming Pool Diatomaceous Earth

I have just recently installed a swimming pool. The pool's filter uses 
diatomaceous earth in the filter. Since the cost of the swimming pool
diatom powder is about $ 5.00 for a 25 lb. bag vs. $ 15.00 for a 5 lb.
bag of Vortex diatom powder, could I use the swimming pool powder in
my tank's diatom filter? Having read the labels on both packages, they 
appear to be the same. Has anyone done this? What were the results?
Your input would greatly appreciated. The plants and fish you save may 
be mine <g>!

Phil White