CC starfish and invertabrite loss?

Question
Hello.

   A month and a half ago (Christmas) my family set up a 36 gallon salt water tank FOWLR.  I cycled 38lbs of live rock and a store bought bag of "live sand" (about 1/2" thick) and then introduced two acclimated mollies to help establish some bacterial growth.  All was well so over the next few weeks I introduced a juvenile tomato clown fish, a Dottie back, and another damsel, the exact name of which escapes me now.  For cleanup crew I (over a few weeks) introduced 8 small snails, 8 small hermit crabs, a male and female emerald crab, a blue fiddler crab, and two Turbo snails.  We were really interested in purchasing some chocolate chip starfish, so about a week ago, I purchased one, and slowly acclimated.  He seemed very happy and would move very fast all over the tank.  We went back to the store a few days later and purchased a stunning reddish color CC star (I read from your forums now that my tank is to small...)  This second star did not have quite the gripping power as the first one, but none the less was very active for many days.  The last few days I have noticed chunks have been taken out of the reddish CC star, exposing his white flesh underneath.  Today I awoke to find my female emerald crab dead, and fearing the worst, moved a bunch of live rock around to find that the blue fiddler had also passed on.  I have yet to find a dead hermit crab or snail, but my turbo snails have appeared to be a lot less "turbo" so far today.

   I have a few questions... has anyone known a dottie back to eat parts of a starfish? My dottie back has a history of attacking brightly colored things (namely red or orange, however the tomato clown will not take his crap).  I have personally observed the dottie back knock the red starfish off of the glass, he pestered and nipped the fins off of my bright orange molly until it eventually died, and has knocked red hermit crabs off of the live rocks they were trying to climb up.  He is kind of like a bull, attacks anything red he sees...  Also the last spot that the red starfish was seen in was near the dottie back's "lair."  My original, brown starfish shows no signs of deteriorating, and goes through phases of extreme activity to not much activity at all.

   My starfish and fish diet has been Formula 2 frozen food (a meat and algae) and tropical flake.  I read on your forum that my stars require more of a meat diet, however in the short period of time I have owned them, could that be contributing to its demise?  Is it possible that I am starving my clean-up crabs? I occasionally drop a few larger chunks of formula 2 to the bottom.  Any tips or suggestions would be greatly appreciated.  I also have been changing two gallons of water every other day for a week and a half to try and drop some nitrate levels (from 15ppm, my tap water tests at 5ppm) and have been using water conditioner.  I have added a SeaChem Purigen Filter to my filtration system a week ago to try to remove more nitrates, but to no avail...

A few hours after removing the dead critters I tested the water parameters at 12 noon (day cycle is from 7:30am-8:30 pm, on a timer)

Salinity:          Just over 1.022
Temp:          76 F
PH:          8.0
Ammonia:          0 ppm
Nitrite:          0 ppm
Nitrate:          15 ppm   (Still a daily frustration)
Copper:          0 ppm
Calcium:          440 ppm

Few more questions I just thought of.   Do I need to remove my deteriorating CC star from my system? Will he adversely affect my other tank mates if his condition worsens? I currently have his separated (not quarantined) from the other tank mates in hope he will get better.


Thank you for your time and expertise....   
-Matthew

Answer
well, im really stumped on this one, the only thing i can think of is that the tank was used previously with copper medication, copper is so lethal to inverts that the smallest bit of it can kill them, such a small amount it wont even show up on a copper test kit. i have never heard of a dottyback eating a starfish i can only think that he is suffering from the melting starfish disease, not a scientific name but no one knows what causes it and there has yet to be a way found to reverse it. usually chunks fall off and the starfish just seems to dissolve.

but this does not explain the loss for your clean up crew, i am starting to think your tank was not fully cycled when you added them, because the choclate chip stars are more resiliant the the red variety this would explain the deaths, or deterioration.

sorry i could not be that big a help but hope that does something for you. also your tank will most likely be fine with the two stars, it is not too small.