San Francisco starter

I received my San Francisco starter a few days ago and it's looking great I have my own starter that I use for most of my breads that is not sour and I purposely maintain it that way.
I keep 300 grams of starter, feed every 12 hours when kept on counter. If its kept in the refrigerator I'll take out a couple of days before hand and start feeding every 12 hours. Whenever I feed it I dump all but 100 grams of the starter out and feed 100 grams bottled water and 100 grams of flour made up of 85% high guten flour ( all trumps), 10% whole wheat (KA), 5% rye (KA). I'll make my levain from that starter. If I recipe calls for 600 grams of starter (levain) I'll only take a couple of spoonfull's my starter and add 300 grams of flour and 300 grams of water let sit on on counter for a couple of hours, then take a scoop see if it floats in water when it does I'm set to go. I don't always want a sour bread I found this method makes a flavorful but not a sour loaf.

I know most sour flavor is gotten from a using long cold fermented dough but In addition to that what is the best way to maintain and use this San Francisco starter. I'm looking to bake a very sour loaf about once a week. Just need information concerning the starter maintenance to optimize its sour capabilities.