Am I overfeeding my starter?

Am I overfeeding my starter?

Hi so first post here, this site has been awesome for me in my endeavors into sourdough and artisan breads but I haven’t been able to find a thread that specifically nails down some of my questions thus far… here goes:

I’m in the middle of my second attempt at a sourdough culture and I’ve hit some killer bumps so far I think. My first starter (all white flour) I was keeping at 100% hydration and feeding as per Thomas Keller’s instructions (start with a 100% hydration mix of AP White flour and water, let be for 24 hours then feed at a 1:1:1 ratio every 12 hours) and I gave up after seeing no real activity after about 6 days. It started doubling and bubbling around day 2, but by day 4 or so it was a lifeless mess.

My second starter (the one I’m working with now) I began with whole-wheat flour (to get more wild yeast incorporated) and I had been feeding with 50/50 whole wheat flour to white AP flour and tap water that had sit out for 24 hours. I let it sit for 24 hours, then fed, then sit another 24 hours, and I’ve been feeding it every 12 hours since then. It was looking AWESOME by day 2 or 3 (doubling in 8 hours, bubbling throughout) but in the last 2 or 3 days it has been bubbling much less and barely rising if at all. I stopped using tap water and have since been using Poland Springs bottled water for about 4 feedings and at day 2 or 3 I began using 25/75 mix of whole wheat flour to white AP. Could either of these changes in the feeding have effected my starter culture? 

My hunch is that I’m overfeeding my culture and not letting the yeast take hold, or that by feeding it whole wheat flour consistently i’m introducing too much new life? With my starter appearing as lifeless as it has been, I stirred in an additional 15-20g of whole wheat flour about two or three hours after feeding this morning. 

OH YEAH my other worry is that even at 100% hydration, my starter has been consistently soupy, even if I end up only hydrating about 90% during the feeding process. 

Other information: My starter has been at room temp it’s whole life (fluctuating between upper 60s and mid-high 70s). I keep about 150g or so of starter at any one point. When I say I added a whole wheat supplement, it was probably two tablespoons or so, maybe closer to 10g. It was just enough to make the starter hold a mound in the jar, but since then it’s already returned to a much more runny consistency.

What are your guy’s thoughts and/or suggestions for jump-starting my starter? I’ve been battling with starters for about 2.5 weeks so far and I’m beyond ready for some reliable starter to make some bread already!

Source: Fresh Loaf