The highest I kept my horses in my 65g tank was about 20x volume turn over per hour. I had a complex series of spraybars under the rockwork to generate that flow and to help solve the detritus problem that comes with lower flow tanks. IMO they could have dealt with more, but that was how that tank was setup at the time.
I have a 65g now that is in the maturing phase before I get some erectus that turns over around 25x an hour. This time it is run by a closed loop and te returns are split between spraybars under the aquascaping and a locline return split up with multiple flare nozles.
IME seahorses can handel higher flow then there given credit for, but it is best IMO to break that up as much as possible to avoid any strong currents.
JMO
