I just picked up a bottle of edwal blue toner, to try out and get my feet wet with toning. I did not realize that it will only keep for 3-4 weeks, and I know I don't have enough to tone in that time period, so most of it would probably go to waste. Is there any way to extend it, like to make a different solution with the crystals, instead of pouring them all in the bottle, then mixing at the time needed (I guess more similar to the Berg toners, that had 2 solutions).