The rust spots in the middle of the leaf not the tip... Reverse osmosis water I'ma have to look into that 'preciate it yo. Peace.true true crack in another forum i had said that it does depend on the strains too and different needs for different seeds. As far as the rust spots are they on the leaves themselves or just on the tips? as far as water go if you have any type of wildoats wholefoods or just a place that you can refill water its not that much for reverse osmosis water. I get mine for 29 cents a gallon and it gets the whole worry of what might be in the water off your mind.