I started off with a few that came on some plants etc...then it seemed like they were just overtaking everything, breeding like crazy especially if you have lots of plants in your shrimp tanks.
What I found was that they would compete for the food the shrimps were getting too...ie: barley, algae wafers, even the BW grow....would push the shrimps out of the way for the food and even ate the algae/biofilm off the glass and filters.
In the end I noticed my baby shrimps not making it to juvie stages, and I have just emptied 2 tanks (nano 8 gallons) that were contaminated with these seed shrimps/cocopeds.
I took out all the shrimps and put in a pair of my Killifish...they have cleaned the tanks of every aquatic creature including planaria roud:
My tanks are now clean enough to put shrimps back in and see if it makes any difference to the population growth.