I don't know what that stuff is but that big jug is probably costly. Go to a smaller hardware store and look for Wood Bleach crystals. Comes in smaller containers in the paint section and costs +/- $7. I use the type made by Dap and got it at an Ace or True Value store (can't remember which place). Last I looked Home Depot didn't have it. Use a pinch at a time with some warm water, and using some gloves when handling it is suggested by a number of us here.

Also, there are plenty of threads on oxalic acid so a Bike Forums search should turn some up for more info.