Turbo Snails all Dying!

I have (or rather had) almost 10 turbo snails in my 135 gallon main and 100 gallon sump set up. Suddenly they all have started dying. I have Turbos, Astereas, Nassarius, and maybe a handful of others. But only the Turbos are dying.

Parameters are:
Nitrates: 0
Nitrites: 0
Ammonia: 0
pH: 8.4
Phosphorous: 0.25 (but no algae bloom)
dKH: 12.0
Mg: 1200
Ca: 400

 

Can you be sure they are dying and not just hiding in the substate? A common behaviour of turbos is to burrow under the substrate and only usually come out at nighttime or when they sense food on the substrate.

If you just cant see them, they probably are still alive. Unless you have some stray hermits etc that are picking them off.

 

they are on their "backs" lying there. Haven't moved all day. I don't have all that many hermits running around at the moment ( I need more for such a big set up)

 

Do you run a RODI water filter ?
When I changed from "tap water" to RODI water, I went on vacation for 2 weeks, when I came home all my snails were "agonear".
Filling Evap water from the tap was allowing minerals, calcium etc into the tank, going onto a 6stage in line filter stripped everything out of the water, as a result all my inverts died and most of my coral population never quite forgave me (until I inserted a emporer angel and he ate everything in 24 hours )

Are u sure your mineral levels are right ?

 

Yeah. I check minerals twice a week and dose whenever they get too low. I use a RO/DI system exclusively. I moved into the tank over a month ago (I had everything cycling for a month prior to that) and I never had this problem with the smaller tank. I haven't changed my approach at all. The only new thing is that now I added some small fish: 3 fake percs, 2 banggai cardinals, a damsel, a blue/green chromis, and a blue hippo tang.

 

All too often, Turbos are collected from cooler regions and eventually succumb to temperature stress in our tropical tanks. Whenever I hear that Turbos are the only thing dying, that's always my first guess.

 

Also, how old is the tank? Even though it is good size, it is possible you do not have enough to sustain 10 of them.

 

...
Yup

 

That does seem like a lot if you are using RO/DI water and keeping it clean, and if you aren't it could be copper levels. Also, they physically cannot flip themselves back over even if alive - you have to help them whenever they do.

 

Moved to----- Inverts.