My starters don't like white flours - thoughts?
I've tried a few times to get starters going. While I've been able to use my latest one to bake pretty good breads, I've noticed that as I keep refreshing/feeding with AP or bread flours, it takes longer and longer to rise. It gets to the point that it doesn't double even given 18-ish hours. When I refresh with rye flour, though, it doubles like gangbusters and we're back in business. Making a nearly 100% whole wheat bread works fine, but making a normal sourdough with bread flour and no added yeast is just about impossible to do. The sucker just won't rise. This is what's happened each time I've attempted to make a starter - as soon as I increase the percentage of whole grain flour, it starts rising again.
I guess I'm wondering if you have ideas as to what could be happening, and then I'm wondering if it's ok to just try to maintain something like a 1/2 AP flour/1/2 whole grain flour starter if that's what it takes to get a decent rise. I use KA flour 99% of the time and feed with bottled water. I do the rising on my counter if it's warm out, or in my oven if it's not (which maintains a 77 degree F temp with the light on). I'm not entirely opposed to a whole grain starter as I do a lot of whole grain baking anyway, but the scientific part of me really just wants to figure out why I can't get one working correctly with AP or bread flour.
If this has been covered here before, I'm sorry - please point me in the right direction. I did some googling and didn't see anything helpful. Thanks in advance for any help you can provide.