I myself don't know how to conserve PMDD, but this is a copy of an extract
from www.thekrib.com regarding storing PMDD


Unmixed PMDD constituents are stable enough. The chelated trace mix should
be kept dark, dry and not unduly hot.

Some have noticed mixed PMDD will degrade over time and even develop mold.
Things that will help:

a.. Put your PMDD in a dark brown or opaque bottle (I use well rinsed
glass cough syrup bottles). Light can destablize chelates.
b.. I refrigerate my main stock (mark it well so someone doesn't take a
swig) and leave a small 25ml bottle by the aquarium for convenience.
c.. Since dry ingredients are more stable, only mix up a few month's
worth of PMDD at a time.
d.. Kevin Conlin adds a little HCL to the brew; (about 0.8ml 9M
HCl/500ml). Never tried it myself.
Hope this helps.


Yes i use hcl .I add 1ml for a 500ml water and a keep this in e fridge but i
dont use dark bottle.I try THX