Thanks happy chem, Being a circulation and oxygenation fanatic these concepts are hard to accept. I recently put sponges over the outputs of my HOB's to stop all surface movement. I don't know if I will get used to it or not right now it is driving me batty every time I look at my tanks. I have noticed a difference in co2 levels already without actually adding any, and my plants are all doing well. I guess sooner or later high tech is going to get me. but I'm avaioding it as long as possible.