I agree with all the comments so far,however,the question is vague because there are so many related considerations depending on LR formations,type of species,what foods you are feeding and generally it helps to have very efficient filtration. The fowlr I set up last Dec. 2016 has terrific circulation (30x) ,but it wasn't until it was set up and operating ,that I was able to tweak the systems to meet the bio load demands.These set ups are always a work in progress,as they get fine tuned ,over time.I am still playing with my circulation seven months later...