Question 1, Calcium

[StirCrazy]

Please read http://www.canreef.com/vbulletin/showthread.php?t=23994 to see where this thread is going.

Ok I thought I would start off with probably one of the most monitored elements to all of us... Calcium.

why is it important, how do we maintain it, and why do we try to push for higher levels than NSW even though it slows down coral growth? Or for that matter what level should we be aiming for.

well this should start up some good conversation lets keep it clean and learn.

Steve

[Beverly]

Originally Posted by StirCrazy

and why do we try to push for higher levels than NSW even though it slows down coral growth?

Steve,

I have never read that higher levels of Ca than NSW slows coral growth. Can you provide a quote and source for this statement? TIA

According to.....

http://www.reefkeeping.com/issues/2004-05/rhf/index.php

Most reef aquarists try to maintain approximately natural levels of calcium in their aquaria (~420 ppm). It does not appear that boosting the calcium concentration above natural levels enhances calcification (i.e., skeletal growth) in most corals. Experiments on Stylophora pistillata, for example, show that low calcium levels limit calcification, but that levels above about 360 ppm do not increase calcification.

Back to your question.....

I do not, and never will, use Ca or other reactors to maintain Ca or other reef chemistry levels. Instead, I drip kalk into our reefs every night to help maintain Ca and alk levels. Then, once every 10-20 days, I test for alk, Ca and Mg, record dates of test results and how much I adjust, and adjust all levels at the same time. Sometimes, if the halimeda in each reef is looking a bit ragged, without testing, I will adjust and record how much I add of Ca, alk and Mg in each reef. I use data recorded from previous test results to ballpark the amount of each chemistry component I adjust without testing.

I know you just asked about Ca, but I don't feel right about just talking about Ca when I do the whole shebang at once. If I were to separate the Ca portion of the three components I test and adjust, I would have to reply that I keep Ca levels between 400 to 450 ppm. I also initially aim for higher alk and Mg levels when I test and adjust the chemistry in our reefs. The higher levels of Ca, alk (10 to 12 dKH), and Mg (1300 to 1350 ppm) are in our reefs so they can be slowly utilized by corals, coralline algae, calciferous macroalgae, etc.

I don't know if what I have just described is a useful way to work with Ca and other chemical components in a reef system. Short of testing and adjusting all components weekly, which probably isn't going to happen, this is the best I believe we are going to have in our reefs.

Hope my comments help the discussion begin

[danny zubot]

IMO there are two reasons why people aim for highter calcium levels.

1. Add the calcium to a higher point so that they don't have to do it as often.

2. They believe that it is better for the corals.

My question is; do corals actually get used to higher calcium levels and develop a higher appitite for it over time?

I aim for 380-420ppm calcium, and have begun to feed my corals phyto to give them the little bit extra. I use Kent turbo calcium and dose Kalk weekly to because it seems to buffer my water better. I went through a faze during the winter where I tried every kind of Calcium additive (except reactor) and found that turbo calium was the best to use. It is by far the most concentrated of all additives on the market.

[Samw]

Originally Posted by Beverly

Steve,

I have never read that higher levels of Ca than NSW slows coral growth. Can you provide a quote and source for this statement? TIA

I'm guessing that raising Calcium to overly high levels must result in overly low Alk levels since there's an inverse relationship between the 2. So I assume coral growth slows for that reason.

http://www.advancedaquarist.com/issues/nov2002/chem.htm

"If, for example, you add too much of a calcium supplement, you will drive down alkalinity as you get precipitation of calcium carbonate in the tank. Likewise, adding too much of an alkalinity supplement can result in reduction of calcium. "


I wonder if adding aragonite to my top off water reservoir has any benefit. The fresh water is low in PH and should very very slowly dissolve the aragonite and add calcium and alk into the top off water.

[steve-s]

Originally Posted by danny zubot

My question is; do corals actually get used to higher calcium levels and develop a higher appitite for is over time?

Really depends on the coral, it's not a generalized answer. Only scleractinians will be a concern and of those, only "SPS" are really a factor. Euphyllia, Faviids and the like are so slow growing to begin with that elevations above NSW values will not make much of a difference.

When it comes to "SPS' in particular, the problem is they have a specific level that they strive for, loosely being 410-420 ppm to keep equilibrium with their cells. The coral is constantly depositing the Ca it takes in to rid itself of it. When the level of Ca is artificially raised above that, the coral has to work harder to deposit more Ca. In doing so, it cannot easily match the rate of skelatal growth to tissue growth which is where the stress comes in. More commonly a tank running very smoothly will not have much if (m)any issues except for thin reedy growth. Due to the continual stress of the higher Ca, any upset can easily cause a stress event in the coral it would otherwise be able to deal with. If the higher Ca uses up much of it's already low reserves of energy, there's nothing left when a stress event (temp, pH, salinity etc) comes into play.

http://www.findarticles.com/p/articl...02/ai_n8850134

http://jeb.biologists.org/cgi/content/full/205/14/2107

http://www.advancedaquarist.com/issu...2004/media.htm

http://aslo.org/phd/disccrs/200206-4.html

Cheers
Steve

[Beverly]

Sam,

Reading a little further into the article you posted, I found .....

http://www.advancedaquarist.com/issues/nov2002/chem.htm

Recommended Ranges

Before getting into problems and solutions, let’s first define what constitutes a problem and what does not. Based on published studies3 involving the calcification of corals and other organisms, I recommend the following:

Alkalinity: (due to bicarbonate and carbonate but not borate, so those using Seachem salt must raise this value substantially to accommodate the borate being counted in standard alkalinity tests)

2.5 - 4 meq/L or 7 - 11 dKH or 125 - 200 ppm CaCO3 equivalents

Calcium:

380 – 450 ppm calcium ion or 950 - 1125 ppm CaCO3 equivalents

If you are anywhere within these ranges for both parameters, you do not need to perform any correction on your tank chemistry, though you may choose to do so for other reasons. In this sense it makes no difference what the relationship is between the two values. If alkalinity is 4 meq/L, it is not inherently any “better” for calcium to be at 380 ppm or 450 ppm. Also, these ranges are somewhat arbitrary, especially at the high end. In fact, the primary reason for having a high end at all is that it is often difficult to keep one of these parameters above the minimum end of the range if the other is over the top end. So if one of these parameters is slightly above the high end, and the other is OK, that is not a problem worth worrying about.

So if I go by what the ranges are, I'd be a bit high going to 12 dKH in alk, but it shouldn't pose too much of a problem. At least according to the quote.

[Samw]

Yeah, keeping it within the ranges is good. The problem is when Calcium is overly higher than NSW as what I assumed Steve meant. I don't mean 420-450 range but more like something over 500. In that case, Alk would be overly low. Thus slowing coral growth I assume.

[StirCrazy]

Originally Posted by Beverly

Steve,

I know you just asked about Ca, but I don't feel right about just talking about Ca when I do the whole shebang at once.

not a problem Bev, this is the kind of reasoning and spreading I was hoping to see, related and still on topic but expanding the discussion.

Ok for me to explain the coral Ca thing it would take me a hour.. but I can quote and friend used to be on the board as "powerreef" and all I can remember is his first name, Mike. anyways he sums it up really nice and if you want more deep I am sure I can find it but here it is.
(oh and Steve-s is on track)

"Calcium will actually inhibit the molecules in the coral tissue from growing. Since the coral polyp is always pumping in fresh SW the calcium concentration in the surrounding water is the same as it is inside the molecules of the coral. In order for the molecule to survive and multiply it must lower the concentration of calcium with in it. It does this by attaching the free calcium ion to its outer membrane and then secretes it out and forms the skeleton. So the calcium is a waste product in sense. the real player on growth is the carbonate and the reaction it has with CO2 the zoox releases.
So having any level of calcium in your water that is beyond normal balanced levels creates a huge energy loss the coral has to give up in order to free itself."

So from a few months of reading and following stuff like this I personally aim for ~380ppm for my Ca level.

Some one was talking about Alk, I think it was Bev again.. I always keep mine at 13dkh, my softies, LPS and SPS all exhibit more intense coloration when it is at this level and I personally have never seen a bad effect of it.

Steve

[StirCrazy]

Originally Posted by Samw

Yeah, keeping it within the ranges is good. The problem is when Calcium is overly higher than NSW as what I assumed Steve meant. I don't mean 420-450 range but more like something over 500. In that case, Alk would be overly low. Thus slowing coral growth I assume.

nope I was thinking anything over 400ppm, now how much difference will 400 to 420 make?? I don't know it may be a mm every 6 months. I try to keep mine under 400 and 380 is the target.


Let me explain something first, the Ca levels I am talking about are going to depend on your Salinity also.. there is a balance for salinity VS Ca. for example if your salinity is 1.027 then your Ca should be 415ppm for the balance, higher than this and you are in the zone of diminishing returns, if your salinity is 1.023 then you are probably looking at about 360ppm for a ballanced Ca level, so if you keep the tank at 1.025 then you might want to be aiming for about 390ppm Ca


Steve

[steve-s]

Originally Posted by StirCrazy

nope I was thinking anything over 400ppm, now how much difference will 400 to 420 make?? I don't know it may be a mm every 6 months. I try to keep mine under 400 and 380 is the target.

Yup, that's what I meant in general, Ca should not actually exceed 420 ppm but in reality, the coral begins feeling stress (working harder?) at the 410-415 mark. Personally I keep mine between 400-410 ppm as a rule.

Let me explain something first, the Ca levels I am talking about are going to depend on your Salinity also.. there is a balance for salinity VS Ca. for example if your salinity is 1.027 then your Ca should be 415ppm for the balance, higher than this and you are in the zone of diminishing returns, if your salinity is 1.023 then you are probably looking at about 360ppm for a ballanced Ca level, so if you keep the tank at 1.025 then you might want to be aiming for about 390ppm Ca

Your in the right place, just might want to use a different designation. If keeping your water at 35 ppt, Ca should be 415 ppm. When you reduce the salinity by say 30 ppt, you've diluted the chemistry overall by 15% (30,000/35,000). Typically why some have problem maintaining target levels to begin with. So the 415 ppm would also be reduced by 15% giving you a value of 352.75 ppm. Same explaination, just different route to get there.

Cheers
Steve