Skunk Cleaner Shrimps dead...

Question
Hello there. Just to let you know, I had already asked someone else on this site about this question and wasn't really content with the answer so, I'm trying again. I have a 20 gallon nano. All water specs are kept at "0", ph is kept at 8.2 and temp at 78. A few days ago, I came home from work, and found my two peppermint shrimps were pretty much at deaths door and my two cleaners looked extremely weak, where they couldn't move and wherever the flow was, they were almost flying along with it. Both had very minor twitches going with the occasional antennae moving about. I did a 2 gallon WC immediately, hoping that would maybe help. I've had them for about 6 months with no problem. They've been acting weird for the past few days prior, like staying behind the rocks, just staying still and not being very active, then this. Within a few hours, they finally gave up and kicked it. I do bi-weekly water changes, as I have a skimmer going on the tank. All my water params seem to be perfect, and I just don't understand what happened that killed all of my shrimps. At the last moment, I had realized that skimmers take out Iodine. Could it have been a full depletion of Iodine that killed them? I have never ever had a problem with my 13 yrs of SW keeping, until this. Also wanted to add, I have the following in the tank as well: False percula clownfish, red firefish, green clown goby, blue tuxedo urchin, Hawaiian feather duster, green emerald crab, strawberry crab, two turbo snails, one pyramid snails, 3 narc snails and two bumblee snails. Any answers, pointers or whatever is GREATLY appreciated!!!

Answer
Rich, first i would like to thank you for being so descriptive in your question. alot of the times i dont have much to work with when people leave things out such as tank size, filtration, and all the inhabitants.

as for your little shrimp, it could be several things. first off, having 4 shrimp in a 20 gallon tank is a rather big no no. even if they are supposedly peaceful ornate shrimp they still will protect their territory. i would suggest getting rid of at least one of the pairs if they make it.

as for the iodine depletion, it is very possible this is what did the in. but i would be interested in knowing if the tank has ever been treated with copper. alot of times if you buy a tank used you never know what sort of medication went into it. even the tiy bit of copper left over could easily harm the shrimp. as shrimp are usually more sensitive to it than the other inverts you have such as the urchin.

i hope that gives you an idea as to how to save your shrimp! good luck to you my friend.

Marcus.