Best way to mow crab grass

I have a stand of what i used to call water grass but I think it is crab grass.

It is soaking wet all the time and grows like crazy. It can be 100 degrees out side and the grass is full of water. Just leaves a mess of clipping's on the lawn that tend to build up over the summer. The hotter and the higher the humidity the more it grows. As soon as it gets cool it quits growing.

I'm told that the only way to kill it is to use a chemical before it starts to grow in the spring. If anyone knows how to kill it in the summer I would like to know about it.

Does anyone have a way to mow it so it does not look so bad? I'm mowing 2 or 3 times a week now to keep it from growing as tall.

Thanks