I am on a well and use a hydrologic as well. But I found I still have leaf necrosis issues no matter medium (soil, hydro etc.). I always add calmag back into the water. I learned that forms of certain substances like manganese are soluble in water and pass through RO, so I think I might have a toxicity problem with a micronutrient. So now I am trying a new thing, Ozonating the RO water product and then after it dissipates passing the water through a active carbon post filter. It is a huge pain in the butt, but if it fixes my problem I would be happy. Ozone causes soluble forms of metals to precipitate and they can then be caught by carbon filtration. Fingers crossed.