- Hi guys and girls.
I am ReefMan and today we're going to talk about potassium,
atomic number 19.
Potassium is a alkaline metal which means
that it has one electron in its outer shell.
And it also means that it's very reactive.
It's towards the bottom of the periodic table,
and as you get to the bottom of the alkaline metal row,
they become more and more reactive.
So this is sort of in the bottom-middle
of the alkaline metals.
I think francium and cesium are more reactive.
In our tank, potassium is important
for a lot of biological functions,
especially in things that move.
Just like in people,
in fish potassium is involved in nerve impulses.
It's involved in multitude of different cellular processes
that need to happen for your fish to survive.
Potassium is a silvery metal
that oxidizes quickly in air.
You see that the potassium that I have
is under mineral oil and has a blue layer on it.
This is to keep air off of it because it reacts
with oxygen and you want the actual metal
when you buy a potassium metal.
You see that potassium does react strongly with water.
It quickly sort of turns into potassium hydroxide,
releases a lot of heat,
and also hydrogen gas which bursts into flames so,
generally recommended not to throw potassium
into water like we're doing here.
In your fish tank potassium will most commonly come
from either the food that you're feeding your fish,
or the salt mix that you're using for water replacements
when you do water changes.
In humans we get potassium from things like bananas,
or things that we eat.
We don't take a potassium supplement usually.
And the same in your tank,
you're unlikely to need to actually dose potassium.
If you're running something like I am,
where I dose a carbon source, I dose vodka,
that generates bacteria.
Bacteria use potassium and then I skim out the bacteria
so I'm exporting potassium from my tank,
and so I dose a little bit of potassium,
just to make up for that,
because I do skim out quite a bit of bacteria every day,
and that lowers the levels of potassium
and some other elements in my tank.
Go ahead and test for it.
It's a simple titration that all you have to do,
to test for it and if you find that you're low,
then you can dose a little bit.
Don't dose too much though.
Too much potassium is going to cause a lot of trouble
in your tank.
It's a little bit better to be on the low side,
than the high side.
You'll find that potassium needs to be
around 400 parts per million,
about the same as you would expect your calcium levels
to be for a healthy tank.
If your potassium is significantly higher than that,
you might start to notice burnt tips on your SPS coral.
If it's significantly lower,
the symptoms of that are a little bit anecdotal
but things like,
your SPS receding from the base up,
especially birdsnest coral seems to be sensitive
to low levels of potassium.
Potassium 40 is a naturally occurring
radioactive isotope of potassium.
And even though in nature it's only .01%
of all of the potassium, it is, in our bodies,
the number one radioactive source
that's in the average human body.
Of course unless you've done some kind
of nuclear medicine or something like that.
Potassium is used in the skeletons of the coral
that you're growing in your tank.
It's also used in our skeleton,
and it, beyond that,
is important for nerve impulses
and a bunch of other biological functions.
If you are doing things like growing chaetomorpha,
or sea grass or something like that in your tank,
where you export a lot of algae from your tank,
that is going to be reducing the potassium in your water,
because as the potassium, or as the algae grows,
it uses potassium and the same way as I have
with my bacteria exporting,
if you have algae being exported,
you're going to be depleting potassium.
You might find that if you have blue coral,
your potassium levels might play a role
in the amount of blue pigment that you see.
If you have high potassium levels,
the zooxanthellae that are in your coral's tissue
are not going to be super happy,
and actually can be exported from your coral.
That overall, is a bad thing,
but in our tanks to a certain extent,
it's a good thing because the zooxanthellae algae
is actually brown.
So if you get rid of some of it,
you'll see brighter colors and you'll see more
of the color of the coral show through,
and it won't be blocked by the brown algae
that's growing in the tissue of the coral.
Specifically the blue pigment that you get
in some coral is,
or uses potassium in its formation.
So if your blue corals specifically are low,
you might test for potassium
and then perhaps dose if you're low.
Again you wanna keep it around 400 parts per million,
or about the same as your calcium level.
Thanks for watching.
I hope this was interesting.
Let me know if you have any questions or comments
about potassium in your tank,
and I will see you next time, bye.