Hi, I have a Pond One Cleartek UV 18w. I’m about to set it up directly on my DT. Tank is a 326L. UV states it is 6000L p/h. I have either a pump that is 2000L p/h or a smaller one which is 550L p/h. I have an inline tap I can use with the larger pump, or just set the smaller one at its max of 550L. Which pump would I be better using? What flow rate is the best for trying to combat Coolia? Thanks