I have used these but never on the ST loius river. has anybody used them on the river and tell me whats a good set up with them. i see the river is up this year. What size sinker should i use???

In a boat or from shore? Anchored or dragging? I would say on shore or anchored a 3/8 ounce weight would be fine and hang the float back a few feet from the weight. If your dragging against current go slow and you may have to beef up to a half ounce weight.
These works best sitting or moved very slowly. I caught fish on the white and chart ones the other night.

The size of the sinker will vary by the current or your speed. If you weren't planning on it already use a slip/sliding sinker rather than a few split shot or fixed sinkers. The only places I've used them are areas where the current is slower so that I can get by with less weight and line out. These spots also tend to be a bit shallower.

it sounds like its easier to just stick to harnesses and leadhead jigs. i just had a few floaters in my overfilled box but the current seemed a little tough for them yesterday.

If your pulling spinners against the current your going to want a 2 or 3 ounce bottom bouncer or you will have a lot of line out and be snagging up all the time. A bigger walking sinker would also work but bouncers tend to snag less.
Like the Birthday Boy said you have to figure out the weight when you see what ya have for current, wind, bottom type etc. At times I have changed sizes many times in the day depending on where we fished the river. Experimentation is sort of fun at times and you never know whats going to catch the HOGS.

yeah ive been using 2 oz bouncers or snap weights although it seems the bottom bouncers work better. theres good current but its been worse