[Dag]

Thanks. By closed loop, I was referring to pulling water from the tank and returning it with an external pump without any air contact (including not running it through the sump). The discussion in your article of external pumps was primarily, if not exclusively, in connection with the use of a sump.

I was contemplating the use of two Iwaki RLT100 or Iwaki RLT70 with a Wavemaster Pro. Perhaps you have experience with that, or know someone who does?