Shrimps and Iodine
Hello again, seems like I'm pestering you folks a lot with invertebrates questions lately.  I was looking through the Freshwater Snail FAQ again, and noticed a note by Sabrina
<Me!>
that freshwater shrimp tanks can/should be dosed with iodine
<I first got this notion from another person that had asked about it, and I got the dosing rates from the fella at http://www.franksaquarium.com/ , in case you (or others) wished to know.>
(she recommended Kent reef iodine - I found a bottle of Kent's marine iodine while browsing an LFS this weekend and picked it up) at a rate of one drop per ten gallons every week, and that it may help snails as well. Getting to my questions, does the iodine break down over time in the tank, or get absorbed by the charcoal in the filter, or what?
<It'll get used up by the shrimp, and will break down in time>
Also, is there a way to measure the amount in freshwater, and would you be able to suggest a recommended level?
<I think it highly impractical to test for it....  Iodine tests are very awkward and time consuming, and I'm not even positive they'll work with freshwater.  One drop per ten gallons weekly is a very, very small amount, but really does improve overall health of the shrimps.>
I've been told there are iodine test kits for reef tanks, but the individual who told me that wasn't sure if they would work in freshwater.
<Yeah, I rather doubt that it would.>
I change approximately 10% of the water in my tanks weekly, and 25% once a month, would that be enough to remove any excess to prevent buildup?  
<I think you'll be absolutely fine with that.>
Additionally, can the iodine harm fish or other life forms in the tanks? Other than ghost shrimp and mystery snails, the other tank inhabitants are black phantom tetras and Otocinclus (golden Otos, I believe) in one tank, and African dwarf frogs in the other.  
<I don't know much at all about the frogs - but everything else should be great.  I've used this in a heavily planted tank with some pretty sensitive fish, with absolutely no effect on the fish (or plants) whatsoever.  Wishing you well,  -Sabrina.>
Thanks again for any help you can provide,  Chris

Crayfish
Hi Bob Fenner I have a 2.5gallon tank with a crayfish and a 29gallon hard alkaline cichlid tank with a divider. I want to move the crayfish to the empty portion of the 29gallon tank and was wondering how to go about acclimating him from his neutral water.
<I would "drip acclimate" the crayfish/crawdad to the new water by placing it in a lower position, dropping half the water out, and use a length of airline tubing (with an adjustable knot) to drip (about one drop a second) the cichlid water into its smaller system... Most species (yours... likely an astacid... maybe Procambarus clarkii?) will make this transition easily... after this abrupt mixing, just place the animal by scooping it into a bag or plastic container underwater and put in the larger system>
Ps. I appreciate your past help,
and the speed at which you have replied.
<You proverbially "ain't seen nothing yet". Bob Fenner>

Crayfish
I was wondering wither I could successfully keep a crayfish in a 2.5gallon tank with a sponge filter.
<it would be a little cramped, but it would likely work too. They are incredibly hardy creatures.>