Musings on "hard" water/ high TDS

[Aceetobe]

So...the question is:

What is it that slowly kills plants from water quality?

I understand sodium or bad pH killing plants, however I have a harder time understanding how precipitated calcium and magnesium are a problem.

Has anybody tried watering with a divalent cation chelator? Like EGTA or something of that ilk? It might be cheaper than RO water.

Also might help some of the problems that people get with semi-hydro media.

[Ray]

I think the CaCO3 and MgCO3 accumulating in the medium sets you up for two issues - high pH, and upsetting the osmotic balance, therefore drawing water from the root cells, both upsetting their internal chemistry.

I don't know what impact chelation would have, as that's intended to make a relatively insoluble ion more stable while in solution, so may play little role, if any, upon the process of drying, concentrating, and precipitating.

[Aceetobe]

I was thinking more along the lines of incorporating a chemical injector with a strong solution of EGTA/BAPTA, and perhaps some citric acid to balance out the pH. Would be more like a maintenance thing rather than "saving".

Hypothesis being that the salts really aren't too bad for the plants, but its rather the accumulation of the precipitates that are. By adding a chelator, you're insuring the next time you water it will be "flushed" out, rather than precipitate out.