I've been making Kefir for about 10 years or so. I had milk Kefir and water Kefir at one stage but the water Kefir propagated so fast it was threatening to take over the house like it did with Ali.
I make mine in an unsealed jar and just fish the grains out with a large spoon that has holes in it and transfer them to another jar. I use a stainless steel spoon and I've never had any problems.
When my first child was born we lived in a mouldy house and he got a severe respiratory infection and we nearly lost him. So when my next son was born I cultured some of my wife's breast milk with kefir grains and gave that to him at 2 days of age, and he seems to be immune to everything. I can't prove it was because of the Kefir but a healthy GI tract is largely where our immunity comes from, so it certainly didn't hurt.
One of the best sites I've seen about Kefir is Dom's Kefir site. There's a few spelling and grammatical errors and the site is ancient, so it's not layed out very well but there's tons of info about Kefir there that you won't find anywhere else. That also where my Kefir grains came from.
Dom's All About Kefir in-site
And an excerpt from that site about an early attempt to acquire Kefir grains. I don't know if the story is true, but it certainly is interesting.
In the early 1900s, the
All-Russian Physicians' Society contacted two
Blandovs brothers, who owned a cheese factory in the northern Caucasus Mountains. The society asked the two brothers for their help to obtain the kefir culture. The brothers decided to take on the challenge, and planned to use one of their employees, a beautiful young woman named
Irina Sakharova, to coax a Caucasian prince,
Bek-Mirza Barchorov into giving her some kefir grains. Irina indeed dazzled the prince with her beauty, but the prince refused to give her any of his precious probiotic-jewels, possibly due to strong religious beliefs.
However, the beauty-dazzled prince wasn't willing to giving up Irina, so he instructed some of his men to kidnap her as she returned home. Against her will, the men brought Irina back to the prince's courtyard, where the prince, hoping to win her love, proposed her hand in marriage, however, Irina understandably refused. The Blandovs brothers eventually rescued Irina from the clutches of the prince. Then, backed by the two brothers, Irina brought her case against the prince to the Czar's court. The prince offered Irina gold and jewels as reparation for the crimes done against her, but she refused his offer. Instead, as a settlement of her suit against Prince Bek-Mirza Barchorov, Irina demanded, and received,
probiotic jewels [kefir grains] instead. In late 1908, Irina Sakharova brought the first amounts of kefir to Moscow, where it was used medicinally in lung sanatoriums as part-treatment for tuberculosis with good success.