bullsie
Well-Known Member
I would like to know if r/o water is the equivalent of distilled. It came up recently when talking of my r/o system. If there is a difference, what?
water?
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They are not the same.
Distilled water has basically zero minerals because it is made by boiling water and condensing the steam. It also has zero buffering capacity for pH and can quickly become acidic once exposed to air.
RO water has some minerals in it and is much better to use for watering plants.
RO water should be cheaper is you have to buy it.
Distilled water has basically zero minerals because it is made by boiling water and condensing the steam. It also has zero buffering capacity for pH and can quickly become acidic once exposed to air.
RO water has some minerals in it and is much better to use for watering plants.
RO water should be cheaper is you have to buy it.
The residual dissolved minerals in the RO water is dependent upon several factors, with the top four being:
Basically, the membranes are designed to reject X% of the incoming dissolved solids. Most of those we see are in the 98%-99% range, although it varies from 93% up, depending upon the intended application. Even that is more than sufficient for orchids, though - If we use the excellent NYC water as a "benchmark" at 40-50 ppm, that "only 93%" membrane could match that with in incoming supply in the 600-700 ppm range!
- TDS of the incoming water supply
- What those minerals are
- Age of the membrane
- Design of the membrane.
Basically, the membranes are designed to reject X% of the incoming dissolved solids. Most of those we see are in the 98%-99% range, although it varies from 93% up, depending upon the intended application. Even that is more than sufficient for orchids, though - If we use the excellent NYC water as a "benchmark" at 40-50 ppm, that "only 93%" membrane could match that with in incoming supply in the 600-700 ppm range!
NYEric
Well-Known Member
Basically they are "equivalent".
naoki
Well-Known Member
Is distilled water easily available?
In biology lab (we do DNA and some RNA works), we usually don't use distilled water. We call it ddH2O (double distilled), but in reality, it is deionized water (we use Mili-Q for lab works). Here is some info about different methods of water purification:
http://en.wikipedia.org/wiki/Purified_water
In practice (for growing plants), RO should work as others said.
In biology lab (we do DNA and some RNA works), we usually don't use distilled water. We call it ddH2O (double distilled), but in reality, it is deionized water (we use Mili-Q for lab works). Here is some info about different methods of water purification:
http://en.wikipedia.org/wiki/Purified_water
In practice (for growing plants), RO should work as others said.
NYEric
Well-Known Member
yes, they sell it in gallon jugs at Walmart.
naoki
Well-Known Member
Oh, OK. Thanks, Eric, I didn't know it. I wonder if it is really distilled.
I have some customers that raise dendrobates (poison dart frogs), and a few others with marine tanks, and they are all very keen on very pure water, and they simply attach a DI column after the RO. That is probably as close as anyone will come to distilled.
bullsie
Well-Known Member
Ray, what does the DI column do on an r/o system?
naoki
Well-Known Member
Usually deionization (DI) column contains ion exchange resin to removed charged ions. It's an additional step to remove more ions.
Is the operating cost of DI expensive?
Is the operating cost of DI expensive?
The DI column is added to remove the last few ppms the RO system doesn't.
The ones I carry are $35, and are good for about 1000 gallons if the incoming stream is 10 ppm, 2000 if it's 5, etc.
From a plant perspective, I think it's a waste of money.
The ones I carry are $35, and are good for about 1000 gallons if the incoming stream is 10 ppm, 2000 if it's 5, etc.
From a plant perspective, I think it's a waste of money.
naoki
Well-Known Member
Thanks for the info, Ray. It isn't as expensive as I imagined, but I agree that there is no point for orchids.
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