Here is a copy of a letter that I received last night that I would like to share as it is well documented. This is the type of imformation I like to keep in our data base.
" Hello Barry.
My name is Rob Feeney. I purchased some clams last year shortly after meeting you at Macna. You added a beautiful little gold maxima that was 1.5" across as a free hitchhiker... We appreciated it very much, and it's grown in to a fine little clam. Very prominent growth in the last 4 months.
My current system is a 29gal SPS system with very high flow. A small clam island is sheltered from the flow, and is directly under a 250w DE halide.
Temp: 80 degrees F
pH: 8.20-8.25
alk: 9.0dKH (Schuran Jetstream 1 reactor takes care of Ca/alk)
Ca: 420ppm
I used to feed cultured phyto, but after 2 years of culturing I turned to DTs
PO4: undetectable
NO3: undetectable.
As you may recall, I had an issue with pinched mantle with one of my Croceas shortly after introduction to my system. I've made some observations while treating the clam (all 3 showed signs of PM at one point). My overall conclusion is that each freshwater dip performed produced several dead critters, and the duration of the dip seems to have the largest impact.
Now for my journal of events:
First dip:
One Crocea was showing greater signs of PM. As per my reading, I performed a 15 minute feshwater dip to the affected clam only. pH and temperature were matched. I used a dropper full of kalkwasser to match the pH. The Crocea did NOT fully close during the dip. Mantle was out (and still appeared to be ruffled) 2o minutes after re-ntroduction in to the aquarium.
In the while bowl, I searched with a hand-lens. Serveral large ampipods and some gammarus shrimp were present. Absolutely no pyramellids or starfish. A few small (1/4") unsegmented worms were present. They were still moving, but obviously crippled.
The following day, the mantle looked MUCH better. A small amount was still curled adjacent to the excurrent siphon. It's interesting to note that the mantle would regain it's pinched appearance after the lights were out (my clams never fully close at night. About 30% mantle extension is normal). The second day showed the most improvement.
The clam remained with a slight "purse string" area across the mantle at the posterior side. This did not improve, rather worsened with time. At night time, the clam would look worse, escalating to a two-week period after the first dip.
Second (and successive dips):
Many dips were performed similar to the first dip. The time increased 1 minute each time to a total of 20 minutes. Again, temp and pH were matched. Improvements were exactly the same as the first dip; strong improvement the following day, marked my a gradual decline over a period of 2 to 3 weeks.
In the dipping bowl, similar animals were found. Still the unsegmented worms showed signs of life. There were far less ampipods, copepods, and gammarus this time. The clam would continue to eject copepod exoskeletons for days after the dip. (I tried to photograph the contents of the bowl, but was unsuccessful each and every time)
Third round: 2 Croceas infected.
The second crocea showed signs quickly and without any notable change (I'm very thorough with recording any and all changes in my systems) The baby maxima was growing well at this point (2 months) and showed no signs whatsoever. At this point, I decided that it might be more thorough to dip the maxima (which remained unaffected at this point) for a part of the duration. While dipping, all clams still remained slightly open, (and ALL 3 squirted me :^) The maxima got me right in the forehead) Reaction was the same as above, except that the clams completely closed during all dips 20 minuter or more. Animals in the white bowl were numerous. Clams opened up 1 hour after re-introduction. For the FW dip, I was still matching temp, but was no Ionger matching pH.
Duration was set to 20 minutes (Maxima 15 minutes), and 3 successive dips lead to 25 minutes (maxima- full duration after the first dip). Pinching would still be evident after lights-out.
Fourth round: Maxima infected, 2 croceas infected.
The maxima was showing signs of pinching, as well as both croceas. The first crocea to be infected (continuously from introduction) was now much smaller than the other crocea. They were very close to the same size upon introduction. The maxima had grown considerably. Things were starting to turn for the worst.
I was ready for a 30 minute dip, but very worried about my baby maxima, who had been growing well. The night before the dip, I prepared a large bowl with some DTs, and placed all the clams in the bowl for a heavy feeding. It was my hope that the big meal would help them out for the following day. They cleared the water right up! Happy little clams.
The following day all 3 clams were put in a fresh water dip. Temperature was matched. Clams closed tight at 22 minutes. This was a very long half-hour!
In the bowl: numerous critters. Many new animals that I had not seen before. Despite my half-hour photo session, nothing turned out at all. I should've used a black container. I presumed that I'd be dipping again in the near-future, so I wasn't too heartbroken.
The clams did not open upon reintroduction to the aquarium. There was 2 hours of photoperiod left, and all I got was an occasional 'hiccup' from a clam releasing an air bubble. I was very concerned. I checked several times during the night, and was revieved to see the siphons were visable in the early morning. The tiny amount of mantle exposed showed no signs of pinching at all. No tiny ruffles, no purse-strings, nothing. This was a first.
Upon returning home from work that day, I witnessed unprecidented mantle extension. I tried not to get my hopes up, but made a point of showing my wife, houseguests, and even my siamese cat. (grin) Everything looked GREAT. I cautiously approached the tank the second evening after lights out, and witnessed no signs of PM. This would normally be the time that my spirits would be crushed.
It's been 2 months now, and I've yet to see any ruffling around the mantle whasoever. I'm also enjoying a large white ring of growth on all 3 of my clams. At this point, I can spot signs of PM from a 1/4 mile away, and I'm confident that I may have finally moved beyond it.
If I had to do it all over again, I'd likely build up from a 20 minute dip again. (I know you advocate a 20-30 minute dip) My clams still seemed to be healthy, but preliminary observations told me that the problem would always deteriorate into a much, much bigger problem without intervention.
I hope that my experience can help you with your database. I wish I had the means to create a controlled experiment, but I'm afraid that my observations are all that I can offer. For what it's worth, I observered the animals that reamined in the bowl after each dip, and the shear volume of different animals that remained after the final dip really made an impact on me. I have never really suspected PM to be a disease, but water a reaction to something else. My observations of the number of animals that were removed from my clams only strengthen this feeling. An unfair analysis would suggest that a longer duration was required to remove the detrimental animals. Obviously, this isn't suitable for a conclusion.
I hope to be placing an order with your again in the very near future.
Best Regards,
Rob Feeney
Someone brought in a clams with pinched and I did a FWD for 30 minutes and after the dip I placed it in a bowl of saltwater and some DT's and left in there for about an hour and after that it looked great. Like doing a IV 
