If I read that correctly, Pat, I would guess that the RO water played no
role in your experience, but that you "over-alkalinized" things, probably
because - as others have helped me see - leachate pH control is not overly
reliable with orchids.

There is a thread on the Semi-Hydro forum discussing the fact that the
reservoir pH can drop to really scarily-low levels - 3.7 being one I recall.
I never did really figure out exactly what might be happening based upon my
theoretical suppositions relating to gas exchange, carbon dioxide
absorption, etc., but more recently I have heard that [some/all?] orchids
have the capability to lower the pH of the substrate in the root zone,
apparently to force the dissolution of certain metallic ions, which can then
be absorbed.
--

Ray Barkalow - First Rays Orchids - www.firstrays.com
Plants, Supplies, Artwork, Books and Lots of Free Info!


"Pat Brennan" wrote in message
...
Ray,

I was running 100 ppm nitrogen for the Dyna-Gro you use more often. I
think I was running a lower ppm of nitrogen for the Bloom formulation. I
would then add enough ProTech to get me where I wanted to be in terms of
pH. I started using the stuff at a pH of 6.8. As my leachate did not
improve I increased the pH. Before I gave up with Dyna-Gro I was running
it at a pH 7.6 - 7.8. (at that point I was using more than just ProTech
to adjust the pH). It was a most madding time as no matter what pH I
started with my leachate pH continued to drive down.

Although I had some damage to my Paphs and Phrags in a normal bark based
mix, it was the Phals in moss that looked the worst and were giving the
lowest leachate reading. Within the Phals, it seemed that the plants in
the older mix gave worst reading then freshly repotted stuff. I did not
have the time or mindset to do a controlled, double blind study. I really
do not have remember having any problems with my mounted stuff or with
Vandas just in baskets. They were fed when the greenhouses were getting
watered and got clear water the other days.

Pat


"Ray" wrote in message
...
Pat,

Out of curiosity, at what strengths were you using the Dyna-Gro products?
I
used about 1 teaspoon per gallon of each, which gave me a pH of about 6.3
and a nitrogen loading of about 100 ppm.

I had considered that maybe the major difference was the substrate
itself,
as I grow a lot in PrimeAgra in S/H culture, but I also have lots of
plants
in sphagnum, in CHC/charcoal/perlite, and in baskets with little or no
medium, and I didn't have any such problems.

This is most curious....

Oh yeah, one more thing. How can sharing your experience make you a
scum???? I think it has led to an interesting discussion!

--

Ray Barkalow - First Rays Orchids - www.firstrays.com
Plants, Supplies, Artwork, Books and Lots of Free Info!


"Pat Brennan" wrote in message
...
"Ray" wrote in message
...
Whoa!!! I think Pat has unnecessarily painted a real scary picture
there.
snip

I know three growers who have used RO water without any problems. Ray
is
one of them. I know six growers who have cooked plants with RO. I am
one
of them. Ray used Dyna-Gro/ProTekt in RO water with great results for
years. I used Dyna-Gro/ProTekt in RO water and after 3 months my
substrate pH was sitting at 3.6. MSU fertilizer makers do not seem to
be
concerned with adding alkalinity to RO water, while a similar
formulation
from Jack Peters suggests it very strongly. I am of the school that
thinks
alkalinity should be added back into RO water, Ray is not. Why the
differences? I do not know. This is not an opinion thing, both Ray's
knowledge and my own have been learned first hand with years of growing.
Maybe it has something to due with the RO units, the substrate we use,
or
our watering habits. But when you make the switch to RO either you will
have no problems and I will seem like a scum unnecessarily scaring
people
or your substrate pH will crash and Ray will seem like an idiot. I hope
I
am the scum, but the leachate tests will help identify problems before
plants are damaged. I think Ray will agree with me here, I highly
recommend you read these articles before you make the switch.

http://www.firstrays.com/PDF/Part%205%20-%20final.pdf

http://www.firstrays.com/PDF/Part%20...%20quality.pdf

Pat