Help with dying derasa

[Peter Jones]

I think my derasa is beyond help but I would like help to make sure it doesn't happen with the next purchase.

I bought an aquacultured clam about 8 weeks ago online. It looked very good in the tank, seemed to be doing fine until the last week or so. Right now, the mantle is shrinking and the clam is gaping. We haven't seen the foot for about a week. The clam never did seem to settle and was constantly turning and fall over. We "left it alone" as much as possible, trying to follow the advice from the site and other sources.

We had it placed on the sand in a 36 gal. The lighting is two 100K 65W 50/50 compacts about 4 inches above the tank. Water parameters are:

Ph - 8.0-8.2
Nitrite - 0
Ammonia - 0
Nitrate - 20 (but consistent)
Temp - 80 -82 (we are having a warm spell, it is getting over 83 somedays)
Salt - 1.025-1.026
Alk - 8.0
Cal - >550

These are all pretty consistent and other corals and fish in tank seem fine.

I read where clams are sensitive to changes in salinity. I notice that I have the habit of adding the evaporation water almost right over where the clam is located. Although I add the water slowly and gently, could this have been a problem?

Any other help?

 

[mbbuna]

the top off could have added to some stress. how tall is the tank?

2-65watt PC 50/50 isn't a lot of light, there's really only 1-65w, 10k and 1 65w actinic. actinic lighting does very little for photosynthethis

 

[Peter Jones]

The clam is sitting about 21 inches from the light, about 18 inches of it is through water.

 

[RichConley]

<a href=showthread.php?s=&postid=7747654#post7747654 target=_blank>Originally posted</a> by mbbuna
the top off could have added to some stress. how tall is the tank?

2-65watt PC 50/50 isn't a lot of light, there's really only 1-65w, 10k and 1 65w actinic. actinic lighting does very little for photosynthethis

Thats not true. Clams and corals photosynthesize 420 and 450nm light very well.

The problem is low par. So I'd consider it like 1 and a half 65w PCS.

That being said, thats not a lot of light, but then again, derasas dont need a ton. Mines actually under an overhang.

 

[RichConley]

Re: Help with dying derasa

<a href=showthread.php?s=&postid=7747492#post7747492 target=_blank>Originally posted</a> by Peter Jones

Salt - 1.025-1.026
Alk - 8.0
Cal - >550

I'd bet you've got a bad test kit in there. Its pretty much impossible to get your Ca that high and keep your Alk at 8.

 

[mbbuna]

<a href=showthread.php?s=&postid=7759215#post7759215 target=_blank>Originally posted</a> by RichConley
Thats not true. Clams and corals photosynthesize 420 and 450nm light very well.

The problem is low par. So I'd consider it like 1 and a half 65w PCS.

That being said, thats not a lot of light, but then again, derasas dont need a ton. Mines actually under an overhang.

whats "not true" ? your point is basically the same as mine