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Using RO water with no calcium added

Posted by nekbet 6 (My Page) on
Thu, Sep 12, 13 at 22:43

So, after this thread I was helped to realize I was running way too high of EC for lettuce... and had some out of balance nutrients. I was using tap water with 200-250ppm and then adding nutes up to 1100 or so. oops.

So I switched out the main res with a lower nutrient solution using tap water...

And, I did a few lettuce plants with *just* RO water and general hydroponics nutrients, up to 600-700ppm. WIth no calcium or magnesium..

The image attached is a sample of what those turned out... not good... good experiment - now I know what calcium deficiency looks like.

The tip burn was much clearer an indication... the other thread picture was nutrient overload - browning/dying of the new growth, versus this was burning of the tips of old growth even.

Hope it helps someone to identify their problem later...

Follow-Up Postings:

RE: Using RO water with no calcium added

Nice to chalk it up as an experiment ;-).

The worst conditions (which lead to tip-burn) are set up when too much nitrogen is applied as small plants causing an accelerated growth without a chance to transport sufficient calcium to the tender rampant growth, even when it is in concentrations that would be acceptable. Cutting off the calcium after overfertilization is like a lab experiment.

Part two of this experiement might be to do it over again (!!) with [35 ppm] to [100 ppm] of *soluble* silica (SiO2, molar mass = 60) in the nutrient solution from potassium silicate to see whether it added any protection (or made things worse).

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