Here is my experience with FW dipping clams...sorry if it is a little long:
I had the clam disease wipe out 8 of my clams back in July. I had 2 derasas survive the whole mess. One appeared fine, the other was stunted in growth.
I decided that 3 months after the ordeal I should test the waters with a baby gold max. Within 2 weeks mantle pinching began by 4 it was gone

The derasas also seemed to exhibit symptoms again upon introduction of the baby max, almost like the max was a catalyst to the disease going full-blown once again. So, I guess the derasas were carriers of the pathogen/disease whatever...I decided at that point to FW dip the remaining derasas for 10 min. The stunted one did not take well to this and died within the day (mantle shriveled, not expanding again), but the other healthier derasa was fine within an hour or two. So here I go "thinking" the disease is totally gone. I find some clams at a bargain price and try 2 maximas and a crocea a month later. And yes, within 3 weeks the usual pinching began once more. I had read Minh's posts and decided that perhaps 10 min was not a long enough FW dip, so I proceed to dip ALL the clams again this time for 30 min. All clams survived and have not exhibited pinching to this day over 2 months later
My take on this is that once clams have reached a point where their health has deteriorated too greatly (the stunted derasa) they will not survive the dip and there is nothing you can do about it. Fw dipping is stressful and I wouldn't have done it unless I was positive that there was a problem that would lead to the demise of the clams inevitably. If the clams are still reasonably healthy they will survive the dip though. I would wait a few weeks before attempting it again though so the clam can rebuild strength or I am not sure it would survive a second dip...others may have a different opinion on this..
I did not Q the clams after the dip, so I don;t know what advice to give about whether or not it will help. I will Q all future introductions though.
If your clam is extending its mantle well within the day, it will survive. You will know within 2 days at most. The tiny "packets" are normal. I know this as when I recently added another maxima I kept it in Q for 3 weeks just to observe and be sure all was well, and I noticed them . Looks like some sort of waste expulsion I guess.
I hope your clam makes it through this...I understand how stressful this can be!
Take care,
J
PS: I REALLY wish I had FW dipped my clams in July

but I didn't even think to do that...but thanx to Minh and his 30 min recommendation I can now finally keep clams again
