Please help

[slgcmg]

I've always love clams. I bought two smaller clams from an LFS in December. One Derasa and one maxima. Both were doing great so I bought two larger ones at the beginning of January. A squamosa and another Derasa.

Last week, both of my smaller ones died, today my large Derasa looks rough. I've checked for bugs but can't seem to find anything.

Params

.10 phosphates
0 nitrates

Lighting is 10 48 inch t5 and a couple of led strips.

Why can't I keep these alive???

 

[SaltyMeloni]

Cal, alk ??

 

[OrionN]

You should take some picture and post the pictures here. Other than that there is not a whole lot we can do.
Look for parasitic snails. Look for any evidence of fish or shrimps bother him. Pinched mantel disease? (picture needed)
Is the light and water condition up to par? temperature variation during the day?
How are the rest of the animals in the tank? Growing well? any problems?

 

[slgcmg]

I tested calcium and alk last week, calcium was 420 and alk was 8..

I searched for pyramid snails and didn't see any. I will take a pic when i get home tonight. It's a full reef, thousands of zoos, several hammers and frogspawn, huge monti plates and various other corals all thriving and growing.

I watched the tank for at least an hour yesterday and nothing was getting on it...