I will preface this by mentioning, this is MY experience, based on my observations and no scientific data. I know others who’ve had similar experiences, but I am only talking of mine. I dose the full Reef Moonshiners program. I do this as I find it to be a much more stable environment for my acros. This method also saves me money and time. The money that I save on water changes pays for the price of a monthly (more like 5-7 weeks) ATI ICP test. To your question.
He’s also the only person that I know of that sells a pure rubidium supplement. When I first began the program, I accidentally added far too much rubidium, raising my levels to approx. .6 µg per liter. I immediately (within 3 days) noticed explosive growth in my acans and zoas (and a few other soft, fleshy corals). Actually, to the point where I started giving away rocks covered in zoas as they were beginning to dominate my acro growout.
I discussed this observation with others and noticed that we all experienced similar results. I don’t have any scientific backing, or controls to compare to, so take this info as “experimental”. That being said, 300% of NSW rubidium levels definitely did NOT warrant a poor response from ANY corals in my tank.