I don't fully understand dosing?

So to my understanding, dosing b-ionic is to maintain levels and not raise them? I dose 15 ca and 8 alk and my levels always fluctuate. I try to keep my calcium at 450 but it's always at 410 because my saltwater is at 420 and then my animals are using whatever's left. Alk is stable but calcium is the issue. No matter what dosage I use calcium is always at 410 or less. I've heard that you just dose the same and then add turbo calcium to raise it and then maybe adjust your levels a bit to compensate? Is that what I should do? Just keep dosing and when I get to 450 raise my dosage to say 20 of ca? Someone explain in detail, thanks