Trying to get a little more time in my bulk ferment

Hi,

It seems like since summer is hear (Pennsylvania) my Tartine Country Bread is bulk fermenting (overnight) a bit too fast for me.

So my solution I am thinking is cooling down the water to around 35° and using a bit less leaven..........175 grams instead of 200 grams.

I know cooling down the water gets me more time but not sure what happens when I use a bit less leaven.

Thanks for your answers!