inverts dying off

[fliynhi]

I hope someone can help me on here. I have a 55 reef tank thats been set up for almost a year now. I have approximately 120 lbs of live rock, a 2 inch live sand bed, two bta's, three fish (fridmani pseudochromis, yellow tang, maroon clown), three peppermint shrimp and about a dozen different corals. My parameters are:
Salinity:1.028
Ammonia:0
Trite:0
Trate:0
Mg:1480
pH:8
Phos:.1
Alk(dkh):6.3
Calc:480
I use Kent salt mix and do a 10 gallon or 20% water change bi-monthly. Aqua C remora for skimming and use 2 korallia 3's for movement.

I have had numerous turbos die, started with 10 down to three that I can find. A few blue leg hermits, had 6 down to 2. Got a sea hare due to recent hair algea problem, had it for almost a week and found it tumbling on the bottom. Had 6 cerith, down to 3. I haven't found any hitch hikers and the shells just show up empty. The sea hare looks like it just died. No battle wounds to notice. All of the fish and coral are doing great. I thought it might be a water issue but my bta's are doing great as well. I am completely stumped and hope someone on here can provide some kind of guidance as to what I might be doing wrong. As always any and all responses are greatly appreciated.
Shane

 

[fliynhi]

Forgot to mention that I realize my alk is low and I have been working on bringing that up slowly. Using kents buffer for it.

 

[mikchabe]

Have all these deaths happened recently, or gradually during the year you've had your aquarium?

Some snails have lifespans of 1-2 years, so that could be the cause.

Hermit crabs have longer lifespans, but mine tend to go missing over time as well.

Not sure about the sea hare.

 

[fliynhi]

It's all really happened since about April. I noticed I couldn't find a few snails and then found their empty shells. I got everything all at once when I first set it all up. I also put extra shells in there of varying sizes so that the crabs would have new ones to move into as they got bigger. Like I said I only had the sea hare for about a week and thats what really prompted my looking into all of this. It was eating the bryopsis in my tank and then all of a sudden there it was tumbling on the bottom of the tank. Thanks for your response, I'm hoping that with more, I'll stumble across the cause.

 

[VacavilleFC3S]

copper contaminatiton?

 

[Enigma445]

I would agree with the copper contamination. have you added any new fish?

 

[chrisstie]

I think your salinity could be getting too high, it should be down around 1.023-1.025

try bringing it down and seew hat happens before panicking about copper? and are you using a refractometer or a hydrometer? Hydrometers can be innacurate due to a sticky needle and even refractometers can wear out over time / need recalibration so i'd double check on your actual salinity. maybe test it against an LFS or if you have any friends in the hobby with similar equipment to test with.

Also, if you are really concerned for copper ask yourself if you bought the tank new or was it previously used, has any contaminated items been added to it etc.

Also it could be some kind of predator you aren't aware of, some hitchiker maybe? I've found some weird things after my tank has been a year or two old and never knew they were in there.

 

[fliynhi]

Thanks all. I think I may try a phosban reactor and see if I can get it down to zero. I'm sure that will help with the bryopsis problem too. As far as copper, I am positive thats not the case. Never used it and my shrimp and anemones are doing great along with all of my corals. The hitchiker is possible but I didn't see any battle wounds on the sea hare, and the hare is why I finally decided to start checking into this problem. It looks like it died for no apparent reason. I think I am just going to hold off on adding anything new for a few months and see how the remaining CUC does. As far as salinity goes, I can bring it down and see if that affects anything. I use a refractometer to check it and just calibrated it a month or so ago.