Clams losing zooxanthellae?

[benzreef]

I have a 6-7 inch derasa that i've kept for about a year now. The edges of it's mantle are losing pigment and it is slightly retracted to the top scute of it's shell. This clam has only been exhibiting these symptoms for 2 days. I recently added new carbon (replaced after 4 weeks) and started using Silphos GFO from Tunze. Water parameters and maintenance follows:

40B
Ca = 430 Seachem/Red sea
Alk = 5.6meq/l Salifert
Mg = 1450 Salifert
PO4 = 0.055 Salifert (dropping steadily from 0.2ppm)
SG = 1.023 maintained with Osmolator
Temp = 80 constant
pH = 8.1-8.3 night to day
NO2 = 0 Salifert/Red Sea

I dose Two little fishes 2 part A+B every morning by plastic dixie cup to maintain levels on a consistent basis. 25% of the water is replaced every 3-4 weeks. Apart from these basic routines, nothing has changed. I can't get any pictures of the clam now as my camera recently took a trip down the stairs without me.

 

[mscarpena]

Any change in lighting?? FO also pulls out a lot of organics and clears up the water significantly. How much FO did you add. You should start off slow at first because of the drastic changes it can have on water quality. Also you just changed our carbon wich also pulls out organics and clears up water. Did you replace your bulbs recently??

 

[benzreef]

i did not replace the bulbs. i did replace my old VHO magnetic ballast with an electronic one. could the magnetic ballast have underdriven the bulbs, then upon replacement were properly lit? this coupled with the addition of silphos and a carbon change could have done it i think. i am target feeding Combisan into it's incurrent siphon very slowly (and diluted) to see if it may help. If it's not getting enough energy from the alga then it may rely instead on filter feeding?

 

[mscarpena]

I would place a bit of a screen over the tank where the clam is or place the clam at a lower level if possible. I think the clam will most likely recover. Make sure you do changes slowly. It was probably too rapid of a change in lighting and tank conditions.

 

[a4twenty]

try to borrow a camera, a picture is the most important piece of information we can use to diagnose the problem. if you can post a pic of the clam and his surroundings.

how are you running the carbon and GFO??? are they separate?

 

[benzreef]

the clam died today. it had to have been the addition of the new carbon and GFO at the same time. i am running the carbon and GFO in a canister filter in seperate chambers. are there any issues to running these in the same filter? i've never heard anything about it, but if it could be a problem, i will remove one to another filter.

 

[Toddrtrex]

Not sure if or how it effects clams, but your Alk is really high. Wouldn't want it any higher then 3 meq/l.