Hi Goulet (robert?)
No I really believe in my case it has been a case of singing ALK.
It is a lesson in the evolution of a system really. When I set up the tank I had a lot of SPS.. I think I had 62 decent sized ones in there at one point haha... its a 80g shallow so it was pretty packed. I had a tornado come through the area and lost power a long while. As a result I had some die off. What I failed to do was adjust my reactors and such to the new lower alk uptake and as a result I believe I experienced swings that had previously been non-existent.
Over the last few weeks what I've done is keep a much closer eye on my ALK level and I've been using saturated kalk in my top off to keep those levels much more stable. Color is definitely better in the SPS I have left, and my LPS seem to be more than fine.
Several people have suggested a send off water test, and that may be in the future, but for now I believe the issue has been resolved by maintaining a steadier ALK with a supply that more matches my demand.
Of course I plan on things growing so now I'm calling into question whether or not I need to sell the CaRx I want to sell haha.. so if you're considering that one you need to hit me before I change my mind ! ha
In my limited experience sps aren't THAT hard to keep. The challenge lies in stability and not really in specific narrowly defined parameters. I have had a nice sps system before and those numbers were probably a far cry from what most would shoot for, but its where the numbers fell and were most stable, and as a result I experienced really nice growth and success.
So, lesson learned again. Keep levels stable, and keep an eye on the demand you have vs the input.