Yeah, Pat's post did seem a little bit scary. I plan on using the same
fertilizer as you Ray and I am hoping that it work to correct the pH for
me as well.
Thanks for the tips, it looks like the pressure tank and pump is the way
to go.

Dustin







Ray wrote:

Whoa!!! I think Pat has unnecessarily painted a real scary picture there.

The continual use of RO water won't lead to any problems whatsoever... IF
you are smart enough to manage the nutrients and pH well, and that can be
easily done by using a fertilizer formulation designed for pure water and
with the right nutrients.

For about 5 or 6 years I accomplished that by using Dyna-Gro "Grow" formula
and adjusting the pH by the addition of ProTekt. For the last 28 months, I
have used the GreenCare "Orchid Special" for pure water at the designed rate
of 125 ppm N and my plants couldn't be healthier or happier. (I don't have
the wherewithal to do most of those tests Pat mentioned, so I let the
fertilizer companies take care of them for me.)

If you fail to use the RO water intelligently, Pat is correct about
nutritional issues, brought about by either the lack of nutrients being
present or them being unavailable due to pH issues. That latter case can
also lead to certain ion toxicity too, as they are variably available
depending on the pH, and you can actually poison the plants by unknowingly
putting too much of certain ions in solution.

As far as delivering the nutrient solution, first let me suggest that the
small tank that usually comes with an RO system is of little value, if any.
It is a feeble attempt (for horticultural purposes anyway) to convert it to
an "on-demand" system.

I prefer to think of it in two segments: putting the RO in the storage tank
and not overflowing, and pumping it through the dosing pump and hose to my
plants.

For the first part, I attached a simple float valve to the RO system outlet
in the tank. When it's full and flow is cut off, back-pressure in the RO
system triggers an included upstream pressure cutoff valve so the membrane
does not sit there under pressure at idle. (I'd check to see if your
discount system has one, as it prolongs the membrane life.)

As for delivering the "final product" to your plants, I have tried two ways.
The first was a simple in-line pump. Simple and reliable, I had to turn it
on for watering, not dally too much during the process to avoid overheating,
and sure had to remember to turn it off when I was done. My current setup
uses a well booster pump, complete with an anti-backflush valve, a 20-gallon
bladder tank and pressure switch. This was a 1/2 HP Home Depot
off-the-shelf unit, set up with the input coming from the bottom of the
storage tank and the output running through my dosing pump and onto a hose
(and mister, but that's an aside here).

As long as the hose end (or mister solenoid valve) is closed - I use
spring-loaded squeeze valves before the water wands - it is off. When
either is opened when watering, the bladder tank pushes away, and when its
internal pressure gets low, the pump comes on the repressurize it. Yeah, I
invested about $150, but it's reliable and I don't even have to think about
it.