Let me start with an apology...cottagefarmer, sorry I failed to mention the orchids in the original post. Not an intentional oversight, just a head full of too many details. Its often difficult to merge information from various sources and not only do I not always rememeber to ask all of the specifics of a question but often the answers to an initial query run so tangental to the original question, that its hard to stay focused. I also try to be senstitive to the length of a post, so I apparently fall short in the details in the process. Please all, accept my apologies and, if you still have patience, let me try and restate my situation: The gh is small (about 120 sq ft), wood frame, uses a 34" high kneewall of cement block,covered with 10mm twinwall. Floor is mortared used common brick that slopes to a central drain. pics via the URL below It currently has a 16" exhuast fan on thermo, two 16" shutters in the east wall, two 8" circulation fans running low speed 24/7 and (for starters) uses a 1500 watt milkhouse heater to keep night temps around 55-60. The plan (we all have to have a plan huh?) is mixed use in the Intermediate Greenhouse temp range, which I understand to be min 60 at night max mid 80s with a humidity range somewhere between 50- 75%. We'd like to maintain a small collection of orchids (of various types to the intermediate temps range) yet also start spring flower and veggie seeds, perhaps root a few cuttings etc. The gh has only been in operation for less than a month...mostly empty. So far the temps hold OK but the humidity hovers at mid 40s at best during the day. I do not plan a drip system for the gh. Plants will be watered and fertilized individually, or by "group". I do understand that misting and fogging are two of the ways to control and maintain a rise in humidity and that the two systems (fog vs mist) emit a different size water droplet and, of the two, I have read that the small fog droplet size is better for the plants than the (relatively) larger mist droplet size. (I thought I was trying to get input about which of the two systems people were using but, perhaps I failed in that communication as well) Of the two, at least for a start, I am currently (as of 10pmPST last night) looking at the Rainmaker Misting system from Ecologic that uses a high pressure pump and nozzles that produce 50-100 micron size water droplets (about $240). I understand that this is a misting system and that "fog" droplets would be smaller (less than 50 micron)but the cost differential between the two systems (at least from these folks) is big (roughly $240 vs $980). I'm not trying do this gh on the cheap but I'm not made of $ either. I do hear, even within the current answers to my orignal post, a difference of opinion about whether RO is "necessary" for such a system for use on orchids..at the moment my leaning is toward the RO system BUT it might be prudent for me to try the misting system without the RO and watch carefully what happens. It seems to me that cooling (in contrast to only maintaining humidity) is a plus to the deal. Since the gh needs additional humidity and, since that humidity in the form of injected mist would also help cool the gh, I can't see how the two don't work hand in glove, at least to a point. Thanks for your patience. Steve Here is a link that might be useful: gh pics

I think you can get some info from your water company. If you mix your own fertilizers you can compensate for the minerals that are present in various amounts. I just bought an RO system and I haven't used it yet but I can't wait. I was looking for the highest quality ones which were very expensive. I started looking through a very well known internet auction site(I don't know if I can say their name but the name has four letters). Anyway I found nicer quality/more expensive ones. One day I was searching and I found some that were cheaper because a company will start some at a cheap price and let people bid away. I got lucky and got a new six stage RO system with deionizer for $50 with shipping. I say just keep looking on this auction site and be patient because it could take a month or two but you can find a good price. I hope this helps.

As someone well steeped in a medical and science background, I can't really recommend an ionized water system over RO. No offense. Of course all unstudied things remain a mystery, but sometimes there are reasons we don't study things, because they don't make a lot of sense. Water is an extraordinarily weak buffer. You can sway its pH by electrolysis, but upon contact with any small amount of acid or base, it will quickly lose whatever pH it has. Read, stomach acid vs ionized water... stomach acid wins. If your goal is better tasting water, then carbon may be fine. If you want to remove tasteless chemicals and toxins, maybe RO is for you. The claim that there are 80,000 chemicals and toxins in the water supply at one time or another is sort of like claiming that every once in a while somebody gets hit by a bus, or struck by lighting. Yes, they are very real things, like chemicals in water, that may cause harm. But living your life in fear of such things can make people do extreme things, and waste a lot of money. You are not going to stay in your house, and avoid all roads to avoid lighting and buses, nor should every house install an RO system "to be safe." If your city has a bad track record for maintaining its water, you live near a clearly unregulated pesticide production facility, or you live on a farm with a well that has fluctuating water quality, it may be that an RO system is for you for "safety reasons." I still maintain an RO system is for us water snobs that not only want better tasting water, but clear ice, clear tea, and better water for our plants and high maintenance fish....

I would be concerned about 20 year old ducks too! They usually don't live that long. If they die in your air conditioner boy that would send some kind of stink down into the living space. Definately have him get rid of the ducks. :-)