Ditch the minnows and go with jigs. I would be willing to bet that you are getting a lot if bites and don't know it. Don't wait for the thump because it rarely happens in this hot weather. When you go over your brush pile or whatever notice the depth of the top of the pile. That is you target depth. Slowly drop your bait down to it or if you are not over it you can cast to it. I use the count down method to determine bait depth. Now comes the fun. Again do not wait to feel the bite, you want to see it. Watch your line very carefully. If it does anything out of the ordinary SET THE HOOK. For instance if it stops falling - SET THE HOOK. If it moves to one side or the other SET THE HOOK. I think you get the idea.

I was taught this method by a friend that is also a guide. The first time we went he caught about 150 and I caught 1. But the second time he caught his normal 150 but I tore him up. I caught 3. But at least I discovered why I wasn't catching. I can't see. Oh well win some loose some.