I buy 1 lb containers of ascorbic acid powder from amazon for like $12, just a little bit will dechlorinate a bucket of water-you can just eyeball it, I use about 1/8 teaspoon for 5 gallons. For PH down you can buy bulk citric acid meant for canning-also on amazon, but you can buy it at anyplace that sells canning supplies, like walmart or hardware stores. You have to experiment with how much PH down you need, but my water is about 140 ppm and along with my Jack's nutrients, I use 1/4 teaspoon citric acid to bring 3 gallons of water down to 6.3-just to give you an idea. These are two of my favorite products, cheap bulk powders and both are great for plant growth beyond just dechlorination and PH down. Good luck!