- Hello, guys and girls.
I'm Reefman.
Today, we're gonna talk about Magnesium.
Magnesium is atomic number 12.
It's a grey, shiny metallic metal,
just like other things we've looked at,
Calcium, Potassium, all metals.
Unlike those two, though, Magnesium is very unreactive.
So while Magnesium is the ninth most abundant element
in the universe, it is the third most abundant ion
in water, after Sodium and chloride.
And it is so in seawater because it's very unreactive.
And it's so unreactive that an ion of Magnesium
will actually spend several tens of millions
of years floating around in the water,
on average, before it is bound up into something else.
And that's a function of how much there is in the water,
but also how unreactive it is.
Magnesium is actually about five times more abundant
in the water than Calcium, but the way we normally measure
it, parts per million, is a measurement of weight.
And the Magnesium atom is so much lighter
than a Calcium atom, so by parts per million,
it's only about three times more abundant than Calcium,
or around thirteen hundred to fourteen hundred parts
per million Magnesium in water.
You can see Magnesium is a grey, shiny crystal,
and unlike Calcium, unlike Potassium,
it doesn't do anything when you drop it into water.
Magnesium is chemically very similar to Calcium,
so much so that the reactions that our coral use
to build their skeletons that normally use Calcium,
often instead use Magnesium just because it's available
in the water and takes the place of Calcium.
This means that the amount of Magnesium in your water
sort of will go up and down with the amount
of things growing in that water.
The more coral and algae you have,
the more SPS or coral that needs to build
skeletons, the more Magnesium is going to taken
out of the water, just by nature of it sort
of getting in the way of Calcium in those reactions.
That's not necessarily harmful for the thing
that is doing it, but that is the primary use
of Magnesium in our tanks.
Since there is so much Magnesium in seawater,
fish have actually developed specific chemical processes
that go on in their kidneys to excrete excess Magnesium
from their bodies, otherwise,
since it's in the food they eat,
it's in the water they breathe and swim around in,
they would just build up in their bodies over time.
So they need a specific way to export it from their bodies.
And they do that through their kidneys.
Magnesium is actually also very important in the ability
of seawater to buffer itself.
And that's really part of the reason why seawater
is so often between about 8.0 to 8.5 on the pH scale.
Magnesium binds up with carbonate in the water,
and this prevents calcium carbonate from falling
out of solution, from precipitating when it
otherwise would.
Since the Magnesium is in the water,
there can be much more calcium carbonate
in the water than there otherwise would be able
to be, and that's why seawater is in the pH range
that it is, because of the calcium carbonate
that's able to be there only because Magnesium
gets in the way of it precipitating out.
The way calcium carbonate would precipitate
out of water is to form little crystals.
And what actually happens is Magnesium
ends up coating the surface
of the those crystals chemically,
and interfering with another layer of calcium carbonate
being laid down.
And that's how it manages to keep so much in solution.
So I mentioned coral and algae.
That's actually the number one thing that uses Magnesium
in our tanks, so much so that coral and algae can be
up to 4% Magnesium by weight.
Any other calcification process, like the building
of coral skeletons or coral and algae growing,
things like that, any calcification process
in our tank is going to use Magnesium to some extent.
And that's why it's important to have
at least some Magnesium in your tank.
It's very difficult to overdose Magnesium
to the point that it becomes toxic.
There are some information on line
where they use Magnesium concentrates
about 8,000 parts per million to help,
like, harvesting oysters and things like that.
But it's very hard to actually get to that level
unless you're just dumping Magnesium supplement
into your tank.
So it's not necessarily something you have
to worry about having too much of.
There are some salt mixes that are low
in Magnesium and so it is important to maybe measure
your Magnesium level in general.
But it's probably unlikely to be a huge source
of problems for you unless you're dosing
it maybe without knowing it.
Maybe it's high in something that you're dosing.
It could be high in Calcium supplements, actually.
Some Calcium supplements add Magnesium.
Or it could be high in the type of food you're feeding,
so that could be adding Calcium into your tank
without you knowing about it.
Or not Calcium, Magnesium to your tank without
you knowing about it.
And also some salt mixes have additional Magnesium added
to it, and some are also low, so it's good to measure.
It is an easy test to do.
All of the major test kit brands have a Magnesium test.
You should definitely know what it is,
and especially know your tank's level
before you start dosing it.
You wanna keep Magnesium around 13 hundred to 14 hundred
parts per million.
As I mentioned, significant overdosings can cause trouble
but most of your Magnesium is likely to actually come
from the salt mix that you add.
If you do need to raise it, sometimes it used to be
that you could use Kent Marine Tech M
to dose to get rid of Bryopsis.
That has actually not worked because
it's not actually the Magnesium that kills Bryopsis,
it was an impurity in their mix that did it,
and they've since changed their mix,
and it no longer works.
Brightwell Marine makes a Magnesium supplement now
that does still work.
It's called Hydrat-MG, and that mix has
whatever that impurity was that killed off Bryopsis.
So if you need to get rid of Bryopsis in your tank
you can use Hydrat-MG from Brightwell Aquatics.
Raise your Magnesium using that
up to about 15 hundred parts per million,
and leave it there for a few weeks.
Dose as needed to maintain it.
And you'll find that your Bryopsis will actually die off.
It might be easier, though,
to use a drug called Fluconazole,
to do this, it's an anti parasite actual drug.
You can buy it online if you search for it.
You can find information on Reef2Reef,
things like that for dosing Fluconazole.
If you do test your tank, you find
that you're significantly below 13 hundred
to 14 hundred Magnesium, you can go ahead
and raise it.
Use any commercial Magnesium supplement
to do that, just be careful that you don't raise it
by 500 parts per million all of the sudden.
Like anything in reefing, small changes add up over time.
Maybe you only raise it by 50
or a 100 parts per million a day,
and then once you reach your actual level
that you're targeting, just hold it there,
and continue dosing that whatever that amount is
for your tank.
I hope this was interesting.
I'd be interested to know
if you'd had Magnesium trouble or not.
I hope it was interesting, and I will see you next time.
Bye.