I had a sq4200 series (sequence) on my CL, 4200gph, If you went with two of these you won't hear them virtually, also very little heat introduced into the water. That would be 8,400gph at an incredible low power consumption, you would have to consider a 2" inlet over the 1 1/2" on the other pumps to get the maximum gph, that is how they can get so much flow from such a small pump. These are the original pump before the Dart & have a very good power to gph ratio!