On this website, I've gone into quite a bit of detail about how to get a starter established.
Lately I've been experimenting with spelt flour (triticum spelta) in sourdough starter, and I've discovered it's really is a very viable grain to use. Quite often I'll use different grains in starters and try new methods of handling them - mainly because I'm endlessly curious, but also because there are different strokes for different folks...check out 'Introduction to Sourdough Starter' for more on this.
Spelt flour works well in sourdough starter, because it's got a great flavour. It ferments well too, and the protein eventually becomes quite soft, which is good from a starter perspective. It is, however, a fibrous grain, so it makes its presence felt in every bread you make using the spelt starter. If you are trying to avoid wheat, then this won't be a concern. I do suggest you gradually head for the lighter grades of spelt, though. These are less fibrous, and so blend in better with a wide range of recipes, which you'll sooner or later want to try, when the breadmaking bug bites.
Other flours, like wheat, are less strident in terms of flavour. Rye, on the other hand, just walks right in on everything. Spelt sits somewhere in the middle of these extremes.
I mentioned fermentation earlier. All grains will ferment. It tends to be that the more available or flexible the protein is in a grain, the further the fermentation process must go before the starter becomes useful as a rising agent. So grains which have low or soft protein work well in starter. Rye is a good example - rye starter provides an amazing rise to wheat breads.
Let me expand on that point. While in general breadmaking, the baker is looking to develop protein, when making a sourdough starter this is not the objective at all. The idea to keep in mind when producing starter is that you want to promote fermentation, and protein (gluten) actually gets in the way of this process. You want the protein to have broken down a bit before the starter is useable. A glutenous starter is both hard to work with, and will slow down the rising process when put in a dough.
That's the major problem with spelt in sourdough starter. Usually, spelt has a very high protein content, and that's why it makes such good bread. But a lot of people struggle with starter made from spelt flour for this very reason - it's too glutenous! I also think that when you are used to working with wheat, the time it takes for fermentation is quite different.
As I mentioned earlier, Spelt flour ferments well - it has a lot of natural enzymes and yeasts in there, and it holds for a while without turning acid. This is good for our purposes. However, because of the protein, you have to extend the time for fermentation in the first stages of building your sourdough starter. What this means is, if you are used to having your starter ready in a day after feeding, with spelt it will be more like 2 days.
But once fermentation has been established, it actually breaks down faster than other ferments, meaning that you have to feed it more often. I try to keep it in the same rhythm as my other starters, so I tend to make it quite thick - this will give you a bit more time between feeds.
But wait - there's more! White spelt will be very glutenous, and may well turn acid before the gluten begins to break down. But then, it breaks down rapidly. For this reason, I recommend using wholemeal spelt only at first in your sourdough starter - it has less protein, more fibre, and will hold longer before it begins to turn acid. Yes, it will mean that your bread will have a more pronounced spelt flavour, but this can be reduced by lighter flours later on in the doughmaking process.When your ferment is well established, you can lighten the flours you use to feed it.
Meanwhile, don't worry too much about the 'separation' that may be occuring between feeds using spelt flour - just let the process chug along for a few feeds and it will right itself. You don't need to pour off this 'hooch' - just recombine with more flour and a little water at the next feed. Just make the mixture as thick as possible when you feed the starter using spelt flour.
Once you have extablished fermentation in your spelt starter, i usually gradually thicken the consistency of the mixture by increasing the ratio of flour you use each time you feed it. This will prepare the starter for lighter spelts, and change the way the enzymes work in the starter. It'll hold longer between feeds, and yet be ripe and ready for use in about the same time as before.
If you have a starter established already using regular wheat flour, it can be fed with Spelt quite successfully. Because of the way spelt is milled, you will find that it absorbs quite a bit of water - see 'liquid sourdough starter' in this website. Generally, I use one part water to one part flour as a default ratio in all my starters, but the more wholemeal the flour, the more water in the ratio. If you have been using my method, and you have managed to get a starter established, then just start feeding it with spelt.
Spelt tends to exhibit brittleness, like rye - what I mean by this is it seems very stiff when you mix it, and then after a day or so it softens quite dramatically, because the protein is quite brittle, and has started to break down after it becomes saturated with slightly acidic water during the fermentation process.
Bear in mind, though, that different grades of spelt flour make a big difference. Essentially, millers remove more or less of the bran, to create different grades of flour. Spelt flour has more bran than wheat, because the layer of bran is thicker. Have a look at Spelt Flours Explained for more on this.
Wholemeal spelt is, as mentioned earlier, the most viable for use as flour for sourdough starter. It will get things really active, but allow more time than you would with wheat flour. When using wholemeal flour of any kind, whether it is wheat, spelt or rye, use a bit more water. I won't repeat the method here, just have a look at my 7 day sourdough starter recipe. It's exactly the same method, even from scratch. You need to remember to lengthen the times between feeds though.
Happy Sourdough Baking!