Hey Ruth, pressure ratings huh? Well, I checked around a bit, but could not find a Mfgs. site for "Sequence". Plenty of vendors though with good technical informaton, but no "pressure ratings" or "pressure rated" status to be found.
However, a pump like your Hammerhead, that's rated at 5800 gph, and retains 5000gph at 8' head is losing a small percentage of flow for that amount of head. In other words it is a relatively "high pressure" type of pump, and probably about as good as you're going to find for your application, in terms of retaining pressure, and ultimately, flow.
So, you might be pushing about 25 times your water volume with this, once "actual water volume" is considered for you 190 gal. This is a pretty good amount of flow for most tanks this size. It isn't "Megaflow" to be sure, but it is probably about right for flow that you use to keep the bottom clean, and detritus in suspension.
It doesn't sound like you've purchased the OM unit yet. Paul, at Oceansmotions.com is very freindly and helpful, and not hard to get a hold of either. You have a lot of options just with the OM unit if you go that way, and then you could supplement with Tunezs' or whatever to tune in your "Megaflow" requirements. :idea:
There are a lot of options out there, but there's your Hammerhead "pressure rating" anyway.
Best of luck, hope you don't need any! > Wave98