Right, ive got nearly everything i need for my darkroom, just need some black out material, tongs, measuring cylinders and of course a few more rolls to process then im all set. One thing i have been wondering is which chemicals are reusable? I have paper dev, film dev, stop and fixer. Which of these can i store after using and re-use because im a lil stumped on this one. Also, is it worth buying a wash aid?