RO water dangers - Orchid Board

HereticHammer · #1 05-08-2009, 10:05 AM

Ok, I have just built a new orchidarium and it has an automatic misting system in it that I thought I was supposed to use only RO water with so it would not clog.

At our local orchid society meeting last night I talked to a number of folks who had varied opinions on RO water and now I am spooked. Warning this may get long.

I was told that RO water is very corrosive and I have found similar info online. Does this mean that RO is actually worse for the misting sytem than calcium build up and such that would come from city water? The nozzels are high grade and can be taken apart and cleaned BUT using city water would leave calcium build up on the glass since the mist is fine and drifts.

Now, what about the orchids? I was told by some that the RO water pulls good stuff from the orchids because it is so pure. I let the automatic misting system water normally (RO only) and I water with fertilizer with a hand sprayer once a week.

Also, the PH is low already in RO and then when fertilizer is added it can get dangeriously low (I verified this online also.) What do you do about that?

I know I now have to watch my one paph carefully (sanderianum) because it likes more alkaline water I have read and I don't know if oyster shell top dressing will be enough to combat RO and fertilizer PH problems?

I was told that I can condition the RO with tap but that would lead to the calcium deposits on the glass.

I was told there is an RO water conditioner that adds back good stuff sold in aquarium stores that many orchid growers use when using RO water. Will that harm my misting system?

Do any of y'all have misting systems? If so, have you used liquied fertilizers with them? I ask because I could use Dyna-Gro or something similar since it claims to have all the nutrients and micros that are needed for life and then I could add Pro-tekt to up the PH a bit but I fear that in the misting system.

Of course, they say only to make up what you are going to use right away but I assume it would just be weaker over time and not be an actual danger to the orchids.

UGH, I am so confused. I bet you could not tell. LOL

Anyway, if you read this far, I hope some folks can help me figure this out.

Magnus A · #2 05-08-2009, 11:21 AM

I think there need to be some things clarified.

Pure RO water has per definition pH=7 (neutral)!
Though the buffer capacity is non existing. This meen that a very small amount of carbon dioxide will lower the pH drastically!

Are pure RO water corrosive? No not as long it is pure and oxygen free. But oxygeneted and acidified with carbon dioxide, yes, it could be corrosive. Due to the low pH!

What to do? Either you use tap water to buffer your water or if you are scared for the Ca you could by any mineral water and use that instead. There are alot of good minerals in mineral water and usually relative low Ca content.

Danger for your orchids? I would say no, becouse the substarte will Always contain enough material that OSMOSIS will VERY seldom be a problem. (And it is not that the goodies is extracted from the roots but pure water is streaming inte the cells and burst them.)

/Magnus

cb977 · #3 05-08-2009, 11:57 AM

When the three rainbarrels we have run dry, I use RO water for the chids. Have been doing it for over 4 yrs and have seen no ill effects

HereticHammer · #4 05-08-2009, 12:09 PM

Thanks Magnus,

I did call the misting system makers and they said that their nozzles with metal parts that are made to be taken apart and serviced are made to resist corrosion of pure water but that their systems are used in professional situations (zoos and botanical gardens) and can handle anything that I would add to the water and straight tap water. The reason to use RO was only to not have hard water stains and to not have to service the nozzles as often.

So I can add anything I want but I want to try and avoid calcium deposits on the glass of the orchiarium so the mineral water sounds great.

Would it need to be a lot? I use a five gallon reservoir for the misting system to pull from. I also could add just a tiny amount of a complete fertilizer with trace elements too like a Dyna-Gro (or hopefully something cheaper.)

As to harm with the orchids, maybe not for most orchids that can take some acidity but I do worry about the Paph. sanderianum since it is not an acidic tolerant plant and adding fertilizer to the RO without buffer will drastically drop the PH. This site shows RO water's reaction with various commonly used fertilizers:

https://www.msu.edu/user/harveyb/Fertilizers.htm

The Peter's (especially Peter's Excel) which I know many use is really drastic.

The best suggestion I can take from that site that might help the Paph and sit ok with the other orchids is using Dyna-Gro and mixing Pro-Tekt to buffer the PH.

It has been a long time since I used DG because it was expensive but it should not be too bad just to use for the orchidarium.

What do you think? Any of these ideas make any sense or am I still coming at it wrong?

HereticHammer · #5 05-08-2009, 12:13 PM

Quote:

Originally Posted by cb977

When the three rainbarrels we have run dry, I use RO water for the chids. Have been doing it for over 4 yrs and have seen no ill effects

But you are just doing it occasionally? Also, you probably add your fertilizers to it right? That helps (at least for orchids that don't mind acidic conditions.) I have been using straight RO except for the weekly hand sprayer when I fertilize and that was what I was worried about.

cb977 · #6 05-08-2009, 12:40 PM

Quote:

Originally Posted by HereticHammer

But you are just doing it occasionally? Also, you probably add your fertilizers to it right? That helps (at least for orchids that don't mind acidic conditions.) I have been using straight RO except for the weekly hand sprayer when I fertilize and that was what I was worried about.

When the time comes that I have to use the RO, it's steady RO until the next good rainfall which can be weeks away

and I fertilize once a week. All other days it's used for misting everything.

I know your situation is a bit different than mine but I wanted to explain how it is used here

Ross · #7 05-08-2009, 01:16 PM

I have used RO water exclusively for a few years. The secret is to use fertilizer designed specifically for pure water. This will have the carbinates, micro nutrients, etc. added in a controlled dosage so the plants get only what they need/want. As for misting systems, there are more factors involved than nozzle clogging. With additives to the spray water, you will quickly get massive buildups on the inside of the glass. If it's carbimates, then good luck cleaning the glass. If you use acrylic as the container walls, there is no hope of cleaning the inside when you use anything accept pure water. As for the rest of your information, just remember that a terrarium or wardian case is not laboratory conditions. There are too many other factors as Magnus brings up. Many of us have been doing this for years so the info we share comes from direct, personal, observations, not lab experiments. Hope this helps.

billc · #8 05-08-2009, 01:22 PM

Jonny, I think you need a different perspective. Try reading this- www.paphinessorchids.com - The best thing I ever did for my orchids

I wish I had an RO system. Maybe someday...

Bill

HereticHammer · #9 05-08-2009, 01:25 PM

Quote:

Originally Posted by cb977

When the time comes that I have to use the RO, it's steady RO until the next good rainfall which can be weeks away

and I fertilize once a week. All other days it's used for misting everything.

I know your situation is a bit different than mine but I wanted to explain how it is used here

Thanks, that helps alot, it is actually a lot like my situation with fertilizing once a week. I will just be using RO all the time instead of a few weeks at a time.

HereticHammer · #10 05-08-2009, 01:29 PM

Quote:

Originally Posted by Ross

I have used RO water exclusively for a few years. The secret is to use fertilizer designed specifically for pure water. This will have the carbinates, micro nutrients, etc. added in a controlled dosage so the plants get only what they need/want.

The orchidarium is glass so can be cleaned but calcium build up is no fun to get off.

What other complete fertilizer besides Dyna-Gro are there?

I have only tried that one way back when I started growing orchids.