There is no need to use Deionized, distilled or RO water when making up your nutrient solutions. The concentration levels are estimated and have a minimum required level only. There is little danger of precipitates forming from elements in the tap. Just add the powders to tap water and get on with it. If you're in Tesco spend your money on extra beer or a fine wine in lieu of DI water.
The minimum concentration levels for max lighting levels have already been calculated for you. There is no need to get wrapped around the axle. If you are using less than max lighting then you already will have an excess. There is no need to worry about "right range". Maximum uptake rates have already been calculated, therefore if you dose per the stated amounts these are automatically taken care of. A more detailed explanation can be found in this article: EI DOSING USING DRY SALTS
Cheers,
The minimum concentration levels for max lighting levels have already been calculated for you. There is no need to get wrapped around the axle. If you are using less than max lighting then you already will have an excess. There is no need to worry about "right range". Maximum uptake rates have already been calculated, therefore if you dose per the stated amounts these are automatically taken care of. A more detailed explanation can be found in this article: EI DOSING USING DRY SALTS
Cheers,