Does Alk directly affect corals?

sen5241b

sen5241b

Reef enthusiast
Its been said that low alk will cause swings in Ph and thus too low or too high a Ph will affect corals (and all livestock). But, does low Alk have any direct affect on corals?
 
Low alkalinity will have a big effect on a lot of corals.
Corals not only use calcium to build their skeletons,but the carbonate alkalinity also plays a big roll in it.If the alkalinity is to low,SPS and LPS cant build their skeletons and start to decline pretty quick.
 
WELLLLLL..... in short.... no.

You see, alkalinity in water technically refers to the water's ability to resist drops in PH. When we talk about calcium and alkalinity and how they're needed for coral growth... we don't really mean alkalinity. I know that sounds weird, but bear with me.

You see, at heart we hobbyists are lazy people who don't really like to delve SUPER deep into the ridiculous science/chemistry going on in our tanks. We can "pretty much" equate alkalinity to what we really want to measure--carbonate and bicarbonate. Since most of the water's buffering abilities are comprised of those two things.

Am I making sense? We measure alkalinity just as a way to get a general idea of what something else (carbonate/bicarbonate) is doing in our tanks.

Chemistry and the Aquarium - Randy Holmes-Farley
read that.... it explains it FAR better than I ever could.

Think of it this way.... if you're alk is low in your tank, what do most people do?
they put a bit of kalkwasser mix into the water, which is calcium hydroxide. In a method I don't understand, it turns co2 into bicarbonate, which in turn makes alk raise.
 
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Gotta slightly disagree with nde's simplification... I think the short answer is "yes", because coral skeletons are made from calcium carbonate. :) without carbonate, LPS and SPS cannot grow, like Yote said. However, if you've only got softies, alkalinity is less important... except that's what maintains pH stability.

sorry nde, just don't want people to think things are simple. :-P
 
NO, DON'T DO THAT, PLEASE!!!!!
We love it when you answer the questions. Really!
:heartpump:heartpump:heartpump:heartpump:heartpump:heartpump:heartpump:heartpump:heartpump:heartpump
 
tankedchemist said:
Gotta slightly disagree with nde's simplification... I think the short answer is "yes", because coral skeletons are made from calcium carbonate. :) without carbonate, LPS and SPS cannot grow, like Yote said. However, if you've only got softies, alkalinity is less important... except that's what maintains pH stability.

sorry nde, just don't want people to think things are simple. :-P
Click to expand...

I realize you're a chemist, but I don't think you understood the bulk of what I said. A simplified version of what I previously quickly explained is below.

"Alkalinity is a complex measurement. It is not a "thing" in the water. It is actually the summation of many things, all of which together provide a particular chemical property. The reason that aquarists measure alkalinity is that in normal seawater, most of it consists of bicarbonate and carbonate. Bicarbonate (HCO3-) is what corals take up and process into carbonate (CO3--) in order to build their calcium carbonate skeletons. Consequently, alkalinity is an indication of whether or not adequate bicarbonate is present in the water.

Normal to high alkalinity implies adequate bicarbonate, while low alkalinity implies that it may be in short supply. In the absence of any method of supplementing alkalinity in a reef aquarium, the water can rapidly become depleted of bicarbonate. Alkalinity's depletion from normal to unacceptable levels can take only a day or two in some reef aquaria, although it can take longer in aquaria with a lower demand for carbonate. When the water's bicarbonate is depleted, corals that deposit calcium carbonate can become stressed and even die. I recommend that reef aquarists maintain an alkalinity of 2.5-4 meq/L (7-11 dKH, 125-200 ppm calcium carbonate equivalents)." A Simplified Guide to the Relationship Between Calcium, Alkalinity, Magnesium and pH by Randy Holmes-Farley - Reefkeeping.com


As you can see, we measure alkalinity because it gives us an idea of the amount of bicarbonate that is present in the water. It is extremely difficult to test for present bicarbonate with a home test kit, thus we check the alkalinity. PH is also tied closely into this, as levels of carbonate and bicarbonate effect the PH.

"Much, though not all, of the carbon source for calcification comes from external bicarbonate. As the alkalinity is reduced (at a given pH) the bicarbonate concentration (which comprises the bulk of the alkalinity in seawater) will also be reduced. Diffusion of bicarbonate or diffusion of CO2 from the coelenteron can apparently become rate limiting in many corals." Chemistry and the Aquarium

Alright, so what's my point? Obviously maintaining proper alkalinity in your aquarium is KEY to the success of all corals, obviously SPS and LPS the most. But the question at hand was whether or not alkalinity DIRECTLY affects coral growth/calcification and all that... and to that the answer is "No."

Does this make sense??
 
yote said:
I am SOOOOoo confused:shock:
Click to expand...

didn't mean to hit thanks... lol

i'm just being technical, trying to explain a bit more of what alkalinity actually is.

basically:
alkalinity = buffering capacity/ability of water to resist drops in PH (how much it can neutralize before the PH hits something like 4 or 5) --- think of what you do when you test for alk with something like an API test kit, you wait for the color of the water to change. that water color changes when you hit a certain ph, and the amount of the liquid you had to pour in tells you much you neutralized before it hit that ph, and that's your alk.

buffer capacity is determined primarily by carbonates and bicarbonates and hydroxide compounds, which are what corals take up.

I TOTALLY agree, it's very confusing, all you really have to know is that corals don't take up alkalinity, they take up things that determine alkalinity.
 
It is confusing.
So I'm just going to leave it that if its not right,my corals are going to show it.:D
 
tankedchemist said:
no insulting scientists... or me 'n' biff can gang up on you.
Click to expand...

I went to grad school with a bunch of snooty "real scientists" (physicists and chemists, who study and practice *pure science*). I've been told over and over that what I do isn't "real science".

I take your "pure science" and apply it to real life, beeyotches! Plus what I do is a lot more fun than sitting around in a lab all day :D

One of my favorite t-shirts ever says "Science: It works, Bitches". I love it.
 
Bifferwine said:
I went to grad school with a bunch of snooty "real scientists" (physicists and chemists, who study and practice *pure science*). I've been told over and over that what I do isn't "real science".

I take your "pure science" and apply it to real life, beeyotches! Plus what I do is a lot more fun than sitting around in a lab all day :D

One of my favorite t-shirts ever says "Science: It works, Bitches". I love it.
Click to expand...

they don't think eviro. science is "real science"? damn. I'd have been outa a job a long time ago if that were the case.

Maybe you need to move up to Oregon, Biff... everything environmental is "real" here :D
 

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