Emerald crab dead or molt? Dinoflgellates

These crabs have been in my tank for 2 months, I never really see them and this morning I find this on the sand bed. I either have a bad case of dinoflagellates or diatoms I'm leaning more towards diatoms but really don't know, so many problems with this tank I don't want to mess with him if it is just a molt. I've never seen one before .

 

All 3 of my emerald crabs died when I had my Alk spike to 16 dKH, very sad incident.
I can't really tell from the pic, even though I see the crab, I can't tell if it's a molt or a dead crab. When I found mine dead, it was a good while after they died. All I could find was the hollow shell and the legs were nowhere to be found. I assumed my hermits and other clean up crew (CUC) did their job well.

I do see something on your back glass that looks like green hair algae... if so, I would remove manually the best you can, and check your water parameters, specially phosphates.

Did you use tap water to set up the tank? Algae blooms are also very common in a newly set up tank.

 

Gha is the one thing I haven't gotten yet... Knock on wood. I'm running phoban. Will check alk when I get home.

I found 1 live crab but didn't see the others. Nothing usual during the day though. Will it be okay if I let it sit a while?

The back is the cheesy background picture. Let the kids pick it out

 

Yep just let it sit. If it is a molt, it will not hurt anything, if he died it will not hurt anything.

I can go several months without seeing my emeralds and it is only a 28 gal tank that I stare into continuiously, so they are elusive for sure.

 

I guess I'll leave him. This brown algae or diatoms or dino is driving me nuts and I'm just worried that what ever it is is affecting the inverts. I lost a turbo snail a few days ago but I think that's because it fell and I didn't notice it until it was too late

 

well my new goby flipped him over and the crabs started picking at it, if it's not a molt it is definitely dead :-(

 

I have tried three times to keep emerald crabs in my tank.. three of them have just died I don't try anymore, I think they just end up starving I have no algae in my tank at all... sorry for your little crabby..

 

what is the substrate in your tank?

 

Caribsea aragonite black

Big big mistake it shows everything!