Don,
With all due respect - I've been keeping reef tanks quite successfully for over 30 years. With a degree in biology as well, I'd like to suggest that I'm pretty adept at reef husbandry. When I set up my 400 Gal reef 3 years ago, it was with a great deal of knowledge and success that I made the decision to go that large. As I mentioned in the last thread - I lost 3 clams that I've had for more than 1 1/2 years in a fashion similar to how many others here in the NW have reported over the last month or two, both here and in conversations I've had with folks not on the board.
I've tested my water with my own test kits (salifert), as well as taken a sample to an LFS - which tested and verified the results of my testing that there were no issues with my water quality. While I don't for a moment suggest that in some cases there may be issues with water quality, I for one find it remarkable that such a large number of folks (some of whom I know are at least as skilled in maintaining reef systems as I am) are all having odd water quality issues to cause what appears to be a large number of similar/comparable deaths. The fact that every other animal in my tank seems to be thriving (lots of coral growth/polyp extension, tube worms and other inverts flourishing) doesn't in my mind support a water quality issue.
While I certainly have not tested my water for any/every conceivable thing I could, I have tested for all of the usual and necessary parameters, and haven't identified an issue. I'm not suggesting it's parasites or anything else, but certainly think we should explore/discuss the possibility that something other than water quality could be at play.
I personally believe that with the large number of folks experiencing what seems to be a similar set of problems, without necessarily obvious interconnections, we should be having a more open discussion on what is going on that would explore every possibility - as I've maintained, I haven't been able to identify a water quality issue with my tank, yet lost 3 out of 4 clams within a very short period of time, yet had by all appearances been thriving .
Let's have open exploration of what a large number of folks seem to be experiencing..
I think the epidemic is people thinking there is some sort of epidemic. PM is real easy to see and is faily common. Just like the last thread there was speculation and it spiraled into no diagnosis at all. I think its best to look at these things on a tank by tank basis. Not all this "my clams died" and "i did stuff".
This tank has an obvious nitrate issue with only limited success. I dont consider 6mo to a year long term. This tank has issues to begin with and shouldnt have clams if nitrates are so high on a regular basis. Even the OP states "there is nothing wrong with my water" then further states that nitrates are 80 last time they were checked. The clam in the picture is obviously dead and rotted away which will contribute to even worse water quality.
Clams need good water quality, they are not as hardy as some would like to believe. They will survive in poor water quality for months and all of the sudden look like crap and die.
My snap judgment is that the remaining living clam should be remove and given to someone with a large tank with good water quality.
Don