I can't help with that, but I can tell you that A&A gives a lifetime warranty to the original pool owner, and they mean it. I was having issues and didn't think my 10 year old system was cleaning the pool as good as it should. One call to them and they sent out a tech who replaced every head in the pool, the gear and valve pack and helped me setup the run time and speed for my VS pump. I'm still a little bit disappointed with the system performance, but certainly not the service. I think my issues have more to do with the design of the pool than the system itself, since my neighbor's have the same system and it seems to work well in their pools.