I can not warn you enough.... DO NOT USE TAP WATER! RODI is the best other wise you will get red slime, and lots of other issues! you will truely regret using tap. If youre like me and only a few years into the hobbie and dont have alot of equipment or money there are a few options. You can buy water from you shop or simply go to walmart (lmao) and buy their colagen water for .33 a gallon