Hi I am setting up my 92 gallon bow front. it is five feet tall and I am switching my pump. I am installing a hydor 740. it has a max head 7.5 feet. Now that I have replaced my old pump with the hydor I don't think it has enough flow. How many times should I be turning over my water every hour? I changed my pump because my old pump was 100 watts and the hydor is 40 watts and the water flow was only a little more on the other pump. Any suggestions? thanks