One is for LPS the other is for SPS. As far as the effectiveness goes, it's up for debate. I think the ZEOvit system as a whole is pretty well established. It's hard to deny the success of ZEOvit. However, I'm not sure how much of their product contributes to success and how much is snake oil. Disclaimer: I dose from the little blue bottles. I've had success with it before and so far, so good on my current tank, but it's still pretty new.