I made kefir for
years!! I love the stuff, although I have to admit what I loved the most was the raw goat milk kefir.
Have you checked this site for cultures and information? I found it to be a very good site and have used the recipes and have bought kefir grains from them as well:
www.culturesforhealth.com/kefir They say you can use coconut milk with success once you have started the grains in "regular" milk for a bit.
I used water kefir for a bit as well, but I definitely felt like the raw goat milk kefir was doing me more good.
I'll be buying more kefir grains soon and looking into the section on how to use previously frozen milk for kefir making, as my son and his wife have that wonderful raw goat milk I can get!!
My understanding is that the ultra pasteurized milk won't offer enough bacteria for the kefir grains to be able to survive - they simply can't get enough nourishment from the milk - although I've read that the direct set cultures. These can be recultured into a new batch, but only a few times.
With that said, more sites are coming out and saying that the Ultra pasteurized milk makes excellent kefir. Here are a couple of those sites:
www.culturedfoodlife.com/how-to-make-your-kefir-creamy-again/kefirblog.com/types-of-milk-to-make-kefir/ - and don't miss the link at the bottom of the article:
kefirblog.com/making-kefir-with-uht-milk-vs-fresh-milk-is-there-a-difference/ Now, in looking for these links, I came across an interesting product that you may wish to consider - it's food for the grains!! It's called Ecobloom:
www.culturedfoodlife.com/store/product/ecobloom/ I hope this is helpful!!
Happy kefir making!!