Eric,
The expiration date is 5 months after the week of production for DT's live phytoplankton. They set that based on studies by Dr. Rob Toonen that showed that it retained most of its nutritional value for 6 months when properly stored. Unfortunately it can lose its nutritional value in less than a week when left unrefrigerated. Which reminds me of the O.J. Simpson trial: Chain of custody of the evidence.
IF the DT's phytoplankton that you purchased was properly refrigerated from the time it was produced until the day you purchased it, it was still good for another five weeks or more, but if it had been unrefrigerated for any length of time during that period, it's value would have been reduced significantly.
I ordered mine from Premium Aquatics and paid a fortune in overnight shipping just to be sure I got it as fresh as possible. Premium Aquatics is only 250 miles from DT's and the 30-oz bottles they had it stock had been produced the week before. I'm sure there are other reliable sources for DT's, it's all a matter of where you live and what's available. Unfortunately Dennis Tagrin told me he has no distributors in my state at all. I did locate an LFS 120 miles away that had some in stock but the expiration date had already been exceeded. I asked them to read me the date on the bottle over the phone before I made a trip there for nothing. Good thing I did. They were shocked
to find out that there was such a thing as an expiration date on the bottle. It seems no one had ever asked them that question before. They get theirs from their livestock wholesaler in Los Angeles. So even if their bottles had a good expiration date, I would have no way of knowing how it had been "refrigerated" during its journey from DT's to L.A. and then from L.A. to Louisiana. I ordered two 30-oz bottles from P.A. and had them packed with dry ice and shipped overnight.
I agree that juvenile clams require regular feedings of phytoplankton and the new version of DT's with three different species of varying sizes seems ideal. The original DT's seemed to me to be a bit on the small size for clams. It was just
Nannochloropsis oculata, which is only 2-3 microns. The new stuff has three different species:
N. oculata 2-3 microns,
N. salina 4-8 microns, and
Chlorella sp. 5-12 microns. It takes time for their symbiotic algae channel systems to develop and time for them to build up zooxanthellae population densities. When small, they get at least 40% of their energy from filtering compared to only 5-10% from filtering once they are mature.
