Starter triples in 8 hrs- now what?

Put it into the fridge if you don't want to use it soon. Rather than try to convert one of your recipes, why not use a tested and trusted sourdough recipe. I would recommend Norwich Sourdough; I use it frequently even after several years of baking sourdoughs. Also, you can use the search feature on this site for other suggestions....

Each time you feed the starter, discard half first. Just DO IT. In the trash can it goes. Otherwise you end up with jars full of unusable starter.

Then feed it. Once it's tripling in 7 hours, then either put it in the fridge until 1-2 days before you bake (then feed it 2 times or so before using), or else use it immediately (and time your feeding so that you use it in building your main dough just when the starter is peaking (like, doubled and all bubbly), and pace it so that you have ample peaked volume to use in your dough).

As to how to convert, i.e. how much starter to use, if you search for 'convert sourdough' you'll find several threads on this, e.g. http://www.thefreshloaf.com/node/5569/converting-recipe-uses-instant-yeast-sourdough-starter-recipe

There, you'll see people using everything from 2 T of starter (with an overnight ferment) to 1/4 or 1/2 c, to 20% or even 40% starter compared to the overall dough. The less you use, the longer you must wait. I personally use about 1 to 1.5 cups of peaked starter per medium boule, with great success, with a 6 to 8 hour ferment in the winter, and use less in the summer, but you should probably start with more detailed, written instructions from a dedicated sourdough recipe. If you're making a very precise recipe, you measure the water and flour in the starter, and subtract these from the amount put in the recipe. I personally don't bother, as I always end up adjusting the final dough by feel to get what I want.

I recommend starting with some dedicated (and detailed) sourdough recipes, until you get a feeling for the above-mentioned timing and volume, and after that you can start trying to convert your favorite yeast recipes.

I'm assuming you've seen the math and know how much flour you're wasting by not throwing away any discards...

(in case you haven't, here http://yumarama.com/1066/why-discard-starter/)

If you really can't tolerate the idea of throwing away your starter discards, you can keep them all in the same jar in the refrigerator and use them to make quickbreads. Pancakes, waffles, muffins, and cakes all benefit from the addition of some starter in the early stages. Mix most of the ingredients together, leave them on the counter overnight, and then when you want to cook all you'll have to do is add your leavening.

Also, if you're keeping all of your discards, you're going to want to reduce the size of the starter you keep and keep it very dry. I keep mine at about 50-60% hydration and only feed it when building for a bake. Nothing gets discarded.