Ray wrote:

My understanding (I could be wrong, and would be happy to receive a correction) is that the
membranes function by means of a specific pore size, meaning that only ions less than a certain size
will pass. Ions are ions - each is pretty much the same size in any water source. Using
hypothetical numbers here, if I had two water supplies, one with 500 ppm TDS and one with 100 ppm
TDS, and ran them through a good RO unit, I would expect to see my output water with less than 10
ppm TDS, no matter what. If the first had five times the amount of boron as the second, I would
still expect to see approximately the same levels in the output.


John Talpa is probably lurking somewhere, waiting to pounce... But
in my opinion the only difference would be the amount of waste water
generated. You will get more rejected water from the initial solution
of 500TDS than 100TDS. But if the membrane is in good condition, the
output water should be very close in final composition.

Personally, I could see a problem if a grower used 'pure' RO water
and a commercial fertilizer designed for soil grown plants. But does
anybody who goes to the trouble of getting an RO unit do that? I use a
complete hydroponic fertilizer for the very reason that I know I'm
removing trace elements from my water. My fertilizer has boron and
molybdenum and nickel, and deity only knows what else in it.

Rob

--
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1) There is always room for one more orchid
2) There is always room for two more orchids
2a. See rule 1
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