yeah Bob is correct (you really need a newbie like me telling you this dontcha bob ;) My test kit says multiply ppm by 0.056 to get dH so 70ppm is 3.92 Im pretty lucky my tap water measured at 50ppm or 2.8dH. I dont understand why Sydney people arent into dwarfs more :( Steph IDMiamiBob wrote: > Vicky writes: > > << I have a hardness test unit, with the 3 bottles of chemicals, and the > > solution turns blue at 70 PPM. Then you gotta multiply that value by some > > other number to get the DGH. It worked out to about 40.2 out of the tap. >> > >> > > The formula is to DIVIDE by 17.4. 70/17.4 =4.02. Somewhere you are getting a > decimal point off by one place. DH of 4.0 is about right straight out of the > tap for a number of Apistos and West Africans. Others will need it somewhat > softer. > > Bob Dixon > > -------------------------------------------------------------------------