When I'm done with mine, I neutralize it with baking soda then dump it to waste. I figure it's got all the calcium deposits that it cleaned from the cell in that water and I'd prefer not to put it back into the pool.

You don't end up using very much acid at all when using one of the "holders". Only a cup or two if memory serves. You only have to mix up enough to fill the inside of the cell instead of filling a 5 gallon bucket to submerge the cell into.