Yup... what he said. Best to get your own test kits so you can not only test your tank water, but also the water you're getting from the LFS
. Until you know the exact numbers of your water parameters then you're just throwing money away on "solutions". If the water you're getting at the LFS
is bad, then it's just like throwing gas on a fire. And if your nitrates or phosphates are through the roof in your tank, then you can keep dosing with any of the "wonder fixes" and it'll just keep coming back. It's best to find the problem, and fix it.
And just my personal opinion... ditch the PurpleUp, completely. If you have no corals, it's doing no good other than adding a bunch of stuff you don't need. (And even if you had corals... it's still not needed, in my opinion.)
How often are you doing water changes? If you have a cyano
problem, and you aren't doing at least 10-20% weekly, then that would be a good place to start.
Recuring the rock will do nothing really. Your rock is cured already. No need to start over. The rock isn't the problem... it's what's in your water.