Thanks, my next mission will be to get flow right. The tank owner does not want any pumps inside the tank. So I'll have to come up with a closed loop system. I've thought of drilling the tank and hooking 2 x OR3500 up, one on each side with a split output or with swcd's. But then the flow might be to much for the swcd's.
The whole setup is for some one who want to convert a freshwater corner in to a saltwater corner and he is not a patient man. He even offered to buy my setup, just so that he could skip the cycle process.
Thanks for all the info and assistance. My knowledge on marines is onlu 3years old and still very limited.