I have a 2 week old starter that is doubling in just under 24 hours.

I have been using a 2:3:5 ratio so it is relatively stiff.

Tastes sour, smells right.

Lots of bubbles.

I have been using AP flour - however I switched to a cheaper lower grade flour about 4 days ago...this is when I noticed things started to slow a little. Perhaps this flour is lower in protein? could this be it? Ambient temperatures have been consistent and around 25C

I really want to get this up to full strength before I even consider baking my first loaf.

How can I get this thing doubling in 12 hours, in 8 hours etc? Would rye flour help?

Thanks,

Matt