Well this will be my first try at a topic of the week.. I am asking for a lot help from experts out there

I am no expert! Just someone who loves plumbing tank with high flow

Well lets start with - Can you have too much flow? Or not enough flow in a tank?
I think you can not enough flow in a reef tank atmosphere, because you can get things like cynobacteria and such.. But too much? Maybe if you can't keep a coral sitting on a rock...
I have a 210g tank with Reeflo Barracuda pushing about 3000+gph on my filtration side.. I also run two Tunze 6100s on a multicontroller for another 3,170gph each.. I alternate them.. I like SPS and LPS in my tank, so the flow goes great with those corals... But for others it will be too much.. I would say a recommend flow would be about 15x the gallons of the tank...
Flow was also an issue for me when I was thinking about a sand bottom.. I tried a little sand and with all my flow, I had my sand in the back of the reef within a week or so? So how do all you people with sand in your tank, keep it? I would love to add sand, I love the look of it (getting sidetracked here, sorry)..
So how do you control your flow with you substrate would be a great question for this topic...
For determining your flow you want to know which corals like flow and which don't... Make caves and stop the flow near certain corals when needed or get the flow kicking into the acroporas (they love it!)
Thats it for now.. But lets get this thread
flowing for others to learn!!!