It's a free standing frag system. I did notice that one of the browned out Sps is starting to color up with some purple on the tips. I use the Hanna Meter for phosphates and salifert for nitrates. I might be crazy but I really think it was lack of light that was keeping these corals from coloring up. I guess I'll know in a few weeks if they all start to bleach out.
There are many threads on it those Hanna meters where a complete fail not worth it one bit in my opinion. ALK meter is a diffrent story so i bet your po4 is off. Also if you have alot of algea your reading will be wrong due to the algea will eat the po4 so you can't test it.