Wow Weezard what great info. That's the thing about DI water that has always worried me: it's relatively pure and likely to impose osmotic imbalance. Chloramines will not evaporate easily from water, but they aren't bio-available to plants either. So that is probably good in the sense that it retards microbial growth in the water that could harm plants or people. But I am very distrustful of our local treated water. The pH varies between 4.5 and 7.0 over even a day or two. Crazy. I am amazed by how little the absorption ranges for certain ions overlap. There is very little room for error, especially with something like P vs Fe.