"Medical Grade" - all it means is whether it uses oxygen or ambient air. [ but see rog's comments : "Medical Grade" also implies ozone-resistant materials and construction in the ozone path. ] People here report good results with ambient-air generators. They are cheaper, and don't require bottled oxygen. They are apparently reasonable for ozonating water. Personally, I had to use oxygen because we'll be using insufflation and possibly some other delivery methods. If you don't use pure oxygen, you will get impurities because the ozonator will act upon other elements in the air - the big danger being nitrogen. But for water ozonation, ambient air is ok. [ append 11/3/06 - Enaly units e.g. are quite cost-effective for this purpose; see http://curezone.com/forums/fm.asp?i=754382 ] If you need ozonation for anything other than casual use, you cannot have a "toy" generator, you *must* use oxygen feed. You'll get your oxygen from a distributor, so get out your Yellow Pages, but do not tell them what it is for. My distributor, AirGas, instantly asked me what I wanted oxygen for, and would have refused to sell to me (forever) had i told them the truth (i lied to them, saying it was for getting rid of mold in my barn). [ append 11/3/06 - other people have found lying to be unnecessary to get oxygen from their distributors, even their local AirGas distributor. However, I was actually refused, point-blank, when i said it was for personal use. Just use common sense. However, when I obtained a Longevity medical-grade oxygen tank, AirGas (who knew me well by then) refused to fill it, giving three consecutive excuses for why they couldn't do so. I had to drive 25 miles to another distributor. N.B. ] So be careful. Also, get an oxygen regulator (about $100).
If you are serious about a medical-grade ozonator (and you should be), consider the one from EBay from a regular seller there named MyGettinPlace. I got his high-end one (the only difference is in output : $680 or $399). The guy has a 100% positive feedback rating from EBay users, and I can tell you from personal contact with him that his high rating is 100% deserved. See http://myworld.ebay.com/mygettinplace
and just click on [Items for Sale] – you’ll find his two models.
Rog refers to this seller also.
If you want the best and can afford it, get the Plasmafire, it has a lifetime warranty. But you’ll be fine with the Synergy Systems one on EBay. We got the high-end Synergy Systems one, and it is excellent. Don’t worry about the lack of lifetime guarantee, this distributor has never had one fail, and would fix it for you if it did. If you’re rich, go ahead with the Plasmafire model. We are not rich, so we could not buy it ($3200 or $2000). The distributor, Dr. Saul Pressman, is brilliant, and is worth getting to know. See this link for his excellent intro to his ozone generator : http://healingtools.tripod.com/saulsltr.html.
These two brands represent the low and high investment on the best type of ozonator. You can pay $400 or $3200, and the only difference is in output. Here's where you need to understand that "medical grade" does not refer to the method of ozone generation (the "technology") - there is more than one method. For AHT or IV ozonation, you must get a cold-plasma generator - but if you're going to do one of those, you'll want professional guidance in any case. The Plasmafire is a cold-plasma generator. You will note that cold-plasma is hard to find - and you will find liars, so i am told. [ and so I found out. There's a lot of hype (lies) about the term "cold plasma". ]
Do research to validate everything you hear, either here on this forum or otherwise. The reason is, you yourself must understand the how and the why of ozonation. The more serious you are about ozone, the more you must find out.
And ask questions here, to get started. This place is incredibly good.