New to sw, have a question about my sand..

[gottafindnemo]

Heyy! Sorry if thisbisbthe wrong place to post... Im about to start up my first sw tank. Itll be a 25 gallon reef + fish. Wondering how i wash my live sand... I was told need to wash it it dechlorinated water, and not haveing am ro system.makes that a little difficult and expensive with store bought water. Can i use the low low nitrate water out of my discus tank to wash the sand?