- Hi guys and girls, I'm Reef Man
and today I wanted to talk about iodine, atomic number 53.
Iodine is the heaviest stable halogen element
and it is unique among them, where it is a metallic solid
at room temperature and sublimates directly to a violet gas.
If you wanted to speed this up
and you have iodine as a solid,
you can hit it with a heat gun like I am here.
I've got it in a beaker and we're just warming it up
so that it sublimates faster and you can see
the violet gas coming off of it.
Iodine was discovered in 1811 and is named
after a Greek word which means violet colored.
You can see it's a very appropriate name.
There are two forms of iodine that are important
in the reef tanks, iodide, a single atom of iodine,
and iodate, an iodine atom and three oxygen atoms.
Depending on the actual animal,
it will use one of these two things.
Some of them even convert from one to another.
Phytoplankton are a single celled algae,
it's an important thing that does that.
In the ocean, iodine is usually around
0.06 parts per million, however that varies significantly
with where exactly you measure it,
so it's kind of an average value.
You don't need to necessarily target that specifically
in your tank, definitely play around with it
and see what level works best in your tank.
Don't go much above that, you can down to zero
without much detriment.
There are two types of iodine that we use in our tank.
We have Lugol's solution, which can be used
as a dose in your tank to raise the level of iodine,
but is more commonly used as a dip
when you're trying to fix a bacterial infection in coral.
It's actually been used since 1829 as a disinfectant
and it is a disinfectant because di-iodine is very reactive.
It's an oxidizer and it's the active part of Lugol's
that makes it actually work as a dip or a disinfectant.
You can even use Lugol's to disinfect drinking water
in an emergency, say you're camping
or a natural disaster happens, you could use it
in small amounts to sanitize your water.
The other main thing that people dose is potassium iodide.
Potassium iodide, like this made by Brightwell,
is just a solution of potassium iodide and water.
This one, I think it says is, they don't tell you
how much is actually in there, but they guarantee
that it's going to be at least
15,000 parts per million iodine.
Potassium iodide is actually also used to iodize salt.
If you go to the store and you buy salt,
at least here in America,
most of the time you're buying iodized salt.
That's a mixture of salt, NaCl, and potassium iodide.
And that's because most of the things that we eat
here in America don't contain iodine
and so you don't get it as part of your diet
if you don't take it as a supplement.
They found that it's easier to just put it in salt
than it is to get people to go out
and buy a specific supplement, and that's what they do,
here in America at least.
Iodide is the most directly used kind of iodine in our tank.
It's used very much by marine algaes in our tank.
It could be even up to 1% iodine by weight.
If you were to pull out some ketamorpha,
depending on the exact species you have,
dry it out and then analyze what it's actually made of,
you might find that it is 1% iodine by weight,
or even up to 1,100 parts per million iodine.
Most things that use iodine in our tank
actually use it to deter other things from eating it.
That's why, say ketamorpha, can be such high iodine.
Plants that have a lot of iodine in it
don't taste good to fish that eat plants,
so it will survive more in the wild
by having this high level of iodine in it.
Other things that use iodine in our tank,
we have some Gorgonia, sea fans.
These iodine wouldn't build in your skeletons.
Tipicuts use iodine to make something called lucinol-B,
it's a toxic compound and things that are toxic
don't get eaten.
Other things that use it, sponges, they use iodine again
to make toxic compounds, makes them distasteful.
Worms and shrimp both use iodine
in their bodies as they grow.
Adding some iodine can help your Gorgonians,
they can help your shrimp.
It's actually required for the skeleton of a shrimp.
That's one reason why you might consider dosing iodine.
Another reason that you might consider dosing iodine
is something that I wasn't able
to find actual science papers on,
but lots of references to it on forums.
If you have any Blue Acropora
and it's not looking very blue anymore,
you might have an iodine deficiency in your tank.
If you check your iodine, it's low,
bring it up to 0.06 parts per million
and your Blue Acropora might look more blue.
When you're testing for iodine, keep in mind
that there are actually many different kinds
of iodine in our sea water.
Each test kit, each brand of test kit,
tests in a slightly different way,
and so if you were to use a
Kent Marine, let's just make one up,
Kent Marine test kit, and then you were to use
a ATI test kit, they would probably be using
different chemistry to detect iodine
and they would read different amounts
because there are different types of iodine
in your water at different levels.
The most consistent way to test for iodine then,
is to use ICP analysis, like ATI's ICP analysis, or Triton.
These, though, are not particularly sensitive to iodine
because iodine's wavelength is very similar to phosphorous.
If the ICP machine is just slightly out of calibration,
the phosphorous can sort of swamp out
the iodine that's in the water.
I hope this was interesting.
Let me know if you have any questions about iodine.
I'm happy to try to help you figure out what's going on.
We'll see you next week.
Don't forget to like and subscribe.
Bye.