This "LOW FLOW" requirement is an old condition.
Now it is accepted to have a tank with low, medium, and even high areas of flow for a seahorse tank.
As long as you have hitches in each of the low and medium flow areas so they can choose where they wish to be at any given time, you will be ok.
Many people keep seahorses in tanks with ten to fifteen times flow.
Pipefish are not always a good choice because they are almost all wild caught and many times pass on pathogens to the seahorses that they are unable to deal with.
However, this possibility exists with any fish that hasn't been bred and raised in the same facility that the seahorses have been in.