I am having a die off of snails in my tank. I have 12 now I am done to 4 or 5. The activity of my redleg, blueleg, zebra crabs have slowed way down. I added a picaso trigger on 11-27. At that time my level for all good. This die off start before the addition of the trigger. I just started adding Purple Up and Stress Zyme just this week. My N/N are 0, A 0, PH 0 and Calcium around 400. I have a trigger, yellow tailed damsel, domino damsel, clarki clown, sand sifting star fish (which stands buried in the sand) peppermint shrimp and emarald crab. I also have about 30 lbs of live rock in my 55 gal. What could be the cause of this?