Yes, overkill! 500gph is way too much for that tub and one nozzle...it's a good idea to try to keep the nozzles from clogging, but you can turn the spray into a water saw root cutter with that kind of flow...does the pump load up from all the back pressure? Maybe install a bypass loop to reduce pressure or a pressure regulator? I think you have a good idea, but I would try a smaller pump and more nozzles imo, or a pressure regulator, if you have to use that pump. A lower pressure will slow down many of the leaks all by itself, so I would get that pressure problem solved first and then work on what leaks are left.