100% hydration starter deflating?
I have a question about my sourdough starter, which is now about 2 weeks old. I have been feeding it once per day, 200g starter to 100g room-temperature (~78F) filtered water, 50g KA bread flour, and 50g of a locally-grown, locally-milled whole wheat flour (which I keep in the freezer as per the farmer's instructions). I've been keeping the starter in a straight-sided pyrex measuring cup with a piece of tape to mark the level of the dough, and when I mix the old starter with new flour and water, it starts bubbling almost immediately. I'm usually gone for most of the day, so I can't track the starter's progress hourly, but based on the marks left on the side of my pyrex, the dough looks to have doubled in size and then deflated almost back to it's original level. The doubling must happen in the first 8 hours, because I am never there to see the starter at it's topmost point. There are always bubbles on the surface and sometimes it even gets frothy, so I know it's still alive.
My question is whether I will be able to use this starter to make sourdough any time soon? Should I be concerned about the deflation, and if so, is there anything I can do about it (I suspect feeding more frequently)? Also, if I want to store my starter in the refrigerator, can I do that at this point, despite the massive amount of deflation? Thank you for any advice you can give me.