Based upon what I've read, that seems like an extreme amount of UV sterilization for a 55. However....if you would run them just a third of the time with a 250 gallon turnover that would be sensible imo.
Running it slower is overkill unless you have nasty parasites that can get exposed, and running it more often at a higher speed is a waste of money, imo.
10 watts run at 170 gph continuously would in theory wipe out most things in a 55 gallon tank (algae, bacteria, some parasites) you'd want to kill, so this is in theory a waste if it's run continuously. Every 3rd day for example should suppress or eradicate most of the things that would go through a UV filter.
You could probably get a timer to run them every third day, or 6- 8 hours every night. If this is just for algae and tank clarity, and assuming these are absolute steals, I'd consider buying them only if I had bigger tanks in my future.
