Calcium Level HELP

[Nate]

Ok, I cannot figure this out. I currently have a 120 gallon reef tank setup with a bunch of lps, sps, and fish. My salinity & alkalinity readings are within range but ph is around 8. The problem I am having is with calcium. Our calcium levels are around 500 and never drop. I add about 1-2 gallons of fresh RO/DI water daily. I have a C-Skim protein skimmer setup and a 24 watt UV sterilizer. I cannot figure out why the calcium levels are always high. I don't add calcium that often (monthly). I wanted to eventually setup a drip system with kalk, but not until i figure out why the calcium isn't being used up as fast as it should. HELP.

[FishyTim]

test kit?

 

Ok, I cannot figure this out. I currently have a 120 gallon reef tank setup with a bunch of lps, sps, and fish. My salinity & alkalinity readings are within range but ph is around 8. The problem I am having is with calcium. Our calcium levels are around 500 and never drop. I add about 1-2 gallons of fresh RO/DI water daily. I have a C-Skim protein skimmer setup and a 24 watt UV sterilizer. I cannot figure out why the calcium levels are always high. I don't add calcium that often (monthly). I wanted to eventually setup a drip system with kalk, but not until i figure out why the calcium isn't being used up as fast as it should. HELP.

[Nate]

test kit?

 

Are you saying the test kit might be faulty?

[Sugar Magnolia]

The test kit may be faulty, but another thing to check is your magnesium level. Mg affects calcium.

[Origami]

Do you find your alkalinity levels dropping? What is your alkalinity measurement? What is your water change regimen? What brand of salt do you use? Do you dose anything at all (such as Purple Up)?

 

Insufficient magnesium can keep calcium levels from getting high because the magnesium ion interferes with the formation of calcium carbonate. That's not an issue here.

 

Of course, your test kit could be bad also.

[Pat_13]

What he said...Magnesium's primary importance is its interaction with the calcium and alkalinity balance in reef aquaria.

 

What are your ALK and MAG? If you don't have the test take if to your LFS, which is a good way to check your kits.

 

You need to keep an eye on all three. Here is a good read:

www.advancedaquarist.com/issues/nov2002

[Nate]

Do you find your alkalinity levels dropping? What is your alkalinity measurement? What is your water change regimen? What brand of salt do you use? Do you dose anything at all (such as Purple Up)?

 

Insufficient magnesium can keep calcium levels from getting high because the magnesium ion interferes with the formation of calcium carbonate. That's not an issue here.

 

Of course, your test kit could be bad also.

 

Ok, thanks for the input everyone. My alk levels are around 196 ppm and have been stable ever since this tank has been up. I usually do a 40% water change every 4 months or so. I just did a water change last weekend, which had little effect on the calcium levels. I use instant ocean, not the reef crystals, if that is where you are going. I never add premixed water, only fresh RO/DI for topping off. I am going to have my water tested at a local fish store tomorrow. I'll have them double check my calcium and alk levels and also do a mg test. Currently I don't own a mg test but in this specific case i don't think i have an issue with mg. This scenario just doesn't make sense to me. I am praying that my calcium test is faulty and the fish store test results come back reading much lower. Do faulty calcium tests usually have higher readings?

 

What brand name calcium tests does everyone use? I am using API right now. Maybe I should try another brand.

Edited March 20, 2009 by Nate

[Origami]

196 ppm Alk = ~4 meq/liter = 11.2 dKH

 

Without dosing anything, IO should mix up to be around 360 ppm calcium, with alk around 8 or 9 as I recall. Both of your numbers are well above what's typical for IO. It's like the tank is being dosed.

 

Where I was going with the alk question was as follows: Alk drops relatively faster than calcium - to the tune of 1 meq/liter (or 2.8 dKH) for every 20 ppm of calcium consumed. Thus, it is far easier to see alk dropping when corals consume it to build their skeletons than it is to see calcium dropping.

 

If you're not doing frequent water changes, and you're not seeing the alk dropping (you said it's been steady), and you're only doing water changes every 4 months or so, and you're not dosing anything at all, and if your RO/DI is good (assumed - you may want to check this. Do you have a TDS meter on your RO/DI? If so, what reading are you getting? If not, check for calcium and alkalinity in your RO/DI output), and if your corals are growing ... (breathe, whew!) ... then the components for that growth (calcium and alkalinity) are coming from someplace - and it's not coming from the typical outside sources.

 

How are you measuring your pH? If you're using a probe, is it calibrated? What I'm angling toward is a possible low pH (below 7.8) where aragonite begins to return to solution, and the possibility that your sandbed is dissolving and slowly adding calcium and alkalinity back to the water column.

 

Also, do you observe coralline growth in your system?

Edited March 20, 2009 by Origami2547

[Nate]

196 ppm Alk = ~4 meq/liter = 11.2 dKH

 

Without dosing anything, IO should mix up to be around 360 ppm calcium, with alk around 8 or 9 as I recall. Both of your numbers are well above what's typical for IO. It's like the tank is being dosed.

 

Where I was going with the alk question was as follows: Alk drops relatively faster than calcium - to the tune of 1 meq/liter (or 2.8 dKH) for every 20 ppm of calcium consumed. Thus, it is far easier to see alk dropping when corals consume it to build their skeletons than it is to see calcium dropping.

 

If you're not doing frequent water changes, and you're not seeing the alk dropping (you said it's been steady), and you're only doing water changes every 4 months or so, and you're not dosing anything at all, and if your RO/DI is good (assumed - you may want to check this. Do you have a TDS meter on your RO/DI? If so, what reading are you getting? If not, check for calcium and alkalinity in your RO/DI output), and if your corals are growing ... (breathe, whew!) ... then the components for that growth (calcium and alkalinity) are coming from someplace - and it's not coming from the typical outside sources.

 

How are you measuring your pH? If you're using a probe, is it calibrated? What I'm angling toward is a possible low pH (below 7.8) where aragonite begins to return to solution, and the possibility that your sandbed is dissolving and slowly adding calcium and alkalinity back to the water column.

 

Also, do you observe coralline growth in your system?

 

Here is the thing about the RO/DI. It is brand new. I just started using RO/DI water less then a week ago. I have been using my tap water and treating it with NovAqua and AmQuel. So i'll try to do some tests on some treated tap water and see if that was the source. Currently the tds reading on my RO/DI is zero. I am measuring ph with the typical solution and test tube kit. If the sandbed is adding calcium back into the water, how do you deal with that?

Edited March 20, 2009 by Nate

[Origami]

Here is the thing about the RO/DI. It is brand new. I just started using RO/DI water less then a week ago. I have been using my tap water and treating it with NovAqua and AmQuel. So i'll try to do some tests on some treated tap water and see if that was the source. Currently the tds reading on my RO/DI is zero. I am measuring ph with the typical solution and test tube kit. If the sandbed is adding calcium back into the water, how do you deal with that?

 

Aha! There you have it, I think. You've only been using RO/DI for a week. I'll bet that your high levels of calcium and alkalinity came from your treated tap water being used as your top-off up until then. After all, our water is pretty hard here. Go ahead and test your tap water for calcium and alkalinity to see what I mean. Why don't we all use tap water to keep our calcium and alk levels up? Well, it's because of all the other stuff (nitrates, phosphates, and such) that's in it. That's why we use RO/DI even though it takes some of the good stuff away, too.

 

Now that you're using RO/DI, you should see your Alk levels drop. Test it now and test it again a week from now to establish consumption. As Alk drops, you'll see calcium drop 20 ppm for each 1 meq per liter (or 50 ppm) of alk consumed. [The alk conversion factors are as follows: 1 milliequivalent per liter = 2.8 dKH = 50 ppm] Right now, your tank is running at about 11.0 dKH (my original calculation was a little off because of rounding).

 

Let's make some assumptions about where you want to go with your calcium and alk levels. Let's say that you want to set targets of 9 dKH (160 ppm) alk and 420 ppm calcium for your system. That is, you're only looking at a drop of around 40 ppm of alk and 80 ppm for calcium. However, your calcium will only drop around 16 ppm for 40 ppm of alk consumption under nominal circumstances. That means that, if you let your alk levels fall naturally due to consumption, while your alk will be at the right level, your calcium will still be a lot higher than where you want it (it'll be around 484 ppm assuming that you started at 500 ppm).

 

In this case, you're going to want to dose an alkalinity supplement (such as baking soda) to hold your alk levels at the target while allowing consumption to draw down the calcium levels until they reach the targeted level (420 ppm). Once you've got both parameters at your targeted levels, then you can begin to use a balanced supplement (like kalkwasser) to keep things where you want them.

 

Here's a handy reef chemicals calculator that'll help you figure out how much of what to add, the procedure to use, and the precautions you need to take when dosing: http://home.comcast.net/~jdieck1/chemcalc.html

 

And, this is a really good article to read on the subject of how to re-establish your calcium - alkalinity balance: http://web.archive.org/web/20021127040526/...ov2002/chem.htm

(You're in Zone 4.)

Edited March 20, 2009 by Origami2547

[flowerseller]

I would suspect that an all at once 40% water change would clearly have a noticeable reaction on many levels in your aquarium.

 

Curious, no right or wrong answer here, why you choose 40% @ 4 months as opposed to 10% @ 1 month?

 

I'm going to go out on a limb here and say "It's not your sand bed releasing Ca back into the water".

While this is in fact possible, it's not very likely. The pH in the sand would have to be much lower, -7.1-2, than the over all pH of the tank.

Eyeball pH kits typically allow for such a broad result range that can be construed by the light source alone used to read it.

You will not get an accurate "tank pH" reading with a sample taken to a lfs or any private residence for that matter. You will however get an accurate "sample" pH.

I say this because the pH will change in route to.

[Origami]

I'm going to go out on a limb here and say "It's not your sand bed releasing Ca back into the water".

 

I agree, Chip. It's not that. He's been using treated tap water for his top-off water source until just the last week or so.

 

Until he mentioned that he's only been using RO/DI for less than a week (note, the original post implied he'd been using it consistently), it was unclear where the boost in alkalinity and calcium was coming from. Assuming that his test kit was accurate, it HAD to be coming from somewhere because it certainly wasn't coming from his IO salt mix.

 

Below a pH of 7.8 or so, calcium is no longer supersaturated in the water column. Under those conditions, some dissolution (buffering) can begin to occur (from the sandbed) but it would be a real stretch to get to where he found himself (considering the alk levels) unless he were well below 7.8 and (and had a real carbon dioxide problem), then, the corals would begin to melt as well. (For 4 meq/l alk, I'd expect him to have a pH of between 8.2 and 8.5, actually.) That, of course, was highly unlikely.

 

The last post, which confessed the new use of RO/DI water changes the question entirely and, I think, offers a much more likely explanation to his situation.

 

Good question, though. Nate, why aren't you doing smaller and more frequent water changes?

 

By the way, you can also remedy your situation with several, sequential large water changes but, unless you have other contaminants that you're trying to get rid of, you can probably just follow the advice from the links that I gave you up above and get to where you need to be in several weeks.

Edited March 20, 2009 by Origami2547

[flowerseller]

I agree, Chip. It's not that. He's been using treated tap water for his top-off water source until just the last week or so.

 

Until he mentioned that he's only been using RO/DI for less than a week (note, the original post implied he'd been using it consistently), it was unclear where the boost in alkalinity and calcium was coming from. Assuming that his test kit was accurate, it HAD to be coming from somewhere because it certainly wasn't coming from his IO salt mix.

 

Below a pH of 7.8 or so, calcium is no longer supersaturated in the water column. Under those conditions, some dissolution (buffering) can begin to occur (from the sandbed) but it would be a real stretch to get to where he found himself (considering the alk levels) unless he were well below 7.8 and (and had a real carbon dioxide problem), then, the corals would begin to melt as well. (For 4 meq/l alk, I'd expect him to have a pH of between 8.2 and 8.5, actually.) That, of course, was highly unlikely.

 

The last post, which confessed the new use of RO/DI water changes the question entirely and, I think, offers a much more likely explanation to his situation.

 

Good question, though. Nate, why aren't you doing smaller and more frequent water changes?

 

By the way, you can also remedy your situation with several, sequential large water changes but, unless you have other contaminants that you're trying to get rid of, you can probably just follow the advice from the links that I gave you up above and get to where you need to be in several weeks.

 

That is along with what I would believe. That high a Ca # would be a stretch to reach from my tap water.

[Nate]

So i tested my treated tap water and here are the results. Calcium=100-120ppm, Alk/KH=6 dkh 107.4 ppm. So is that high for calcium in tap water? Was that the problem?

 

I also double checked the levels in the main tank and found it hasn't changed. Calcium still at 500 ppm and alk/kh is 179 ppm. Ph is still 8.

 

As to why i do water changes less frequently. Well, our water is always within all parameters and i just see no need to do water changes very often. I could go even longer than 4 months if i wanted to and still have good water.

Edited March 20, 2009 by Nate

[Origami]

So i tested my treated tap water and here are the results. Calcium=100-120ppm, Alk/KH=6 dkh 107.4 ppm. So is that high for calcium in tap water? Was that the problem?

 

I also double checked the levels in the main tank and found it hasn't changed. Calcium still at 500 ppm and alk/kh is 179 ppm. Ph is still 8.

 

As to why i do water changes less frequently. Well, our water is always within all parameters and i just see no need to do water changes very often. I could go even longer than 4 months if i wanted to and still have good water.

 

Yes. With each top off, you were adding more calcium and more alkalinity (carbonate & bicarbonate) to your tank in excess of consumption. Let's say that you were evaporating 10 liters a day and replacing it with 10 liters of treated tap water. In this scenario, you're adding a gram of calcium and about 1.1 grams of alkalinity to your tank every day (since neither calcium or alkalinity leave with evaporation). If this were a 400 liter system (~105 gallons), and only half of this addition was being consumed by calcium carbonate forming organisms, then you're accumulating 500 mg (1.25 ppm) of calcium and 550 mg (1.375 ppm) of alkalinity every day. Over the course of a month, you're adding nearly 40 ppm of calcium to your system in excess of consumption. That is, you'd see an upward trend in your calcium test readings of 40 ppm per month. Alkalinity would, likewise, increase though at a faster pace. At some point, though, calcium carbonate would begin to precipitate out and your levels would top out. Presumably, that's where you are now.

 

Now, the tests that you're doing now to establish your understanding of water quality are incomplete and do not provide you a complete picture of what your water quality really is. I'd advise that you get on a regular program of water changes, certainly more frequent than you're doing now. (I change out about 10% every week - which is probably more than a lot of people do. You could change out 5% a week or even 10% a month.) Doing so does two things: It exports unwanted compounds and ions that are accumulating but that you don't test for (for example, dissolved organic compounds - DOCs, sulfites, and other stuff) and replaces trace elements that are being depleted that you also probably don't test for (for example, strontium and iodine).

Edited March 20, 2009 by Origami2547

[Nate]

Yes. With each top off, you were adding more calcium and more alkalinity (carbonate & bicarbonate) to your tank in excess of consumption. Let's say that you were evaporating 10 liters a day and replacing it with 10 liters of treated tap water. In this scenario, you're adding a gram of calcium and about 1.1 grams of alkalinity to your tank every day (since neither calcium or alkalinity leave with evaporation). If this were a 400 liter system (~105 gallons), and only half of this addition was being consumed by calcium carbonate forming organisms, then you're accumulating 500 mg (1.25 ppm) of calcium and 550 mg (1.375 ppm) of alkalinity every day. Over the course of a month, you're adding nearly 40 ppm of calcium to your system in excess of consumption. That is, you'd see an upward trend in your calcium test readings of 40 ppm per month. Alkalinity would, likewise, increase though at a faster pace. At some point, though, calcium carbonate would begin to precipitate out and your levels would top out. Presumably, that's where you are now.

 

Now, the tests that you're doing now to establish your understanding of water quality are incomplete and do not provide you a complete picture of what your water quality really is. I'd advise that you get on a regular program of water changes, certainly more frequent than you're doing now. (I change out about 10% every week - which is probably more than a lot of people do. You could change out 5% a week or even 10% a month.) Doing so does two things: It exports unwanted compounds and ions that are accumulating but that you don't test for (for example, dissolved organic compounds - DOCs, sulfites, and other stuff) and replaces trace elements that are being depleted that you also probably don't test for (for example, strontium and iodine).

 

So, what I should do is start doing more frequent water changes to bring the calcium levels down? And once I reach the desired levels I will be able to start adding kalk since i am using RO/DI water now? Kalk will also help maintain my alk right?

[Origami]

So, what I should do is start doing more frequent water changes to bring the calcium levels down? And once I reach the desired levels I will be able to start adding kalk since i am using RO/DI water now? Kalk will also help maintain my alk right?

 

See the link to the article that I provided up above in my 10:55 AM post. It'll tell you just what you need to do to get your tank back in balance. Your tank is in Zone 4.

 

Once you're calcium and alkalinity parameters are where they should be, you can begin to use a balanced additive like kalkwasser. Kalkwasser, however, will not correct an imbalanced situation, though. That's why you would first fix the imbalance.

 

While you could address the imbalance with several large water changes, you're numbers do not present a huge problem. I'd follow the approach outlined in the article. That is, stop dosing (that's what you were effectively doing when you were using non-RO/DI tap water for your top-off) and use your RO/DI water for your top off source. Let your alk and calcium levels fall naturally (as your corals and other livestock consume it). Once one of the parameters hits the level where you want to maintain it (this will be alk in your case), you're going to need to take action to sustain that level while the other parameter comes back into line. In your case, where alk will reach the target level first, you'll probably be dosing regular old Arm & Hammer baking soda (in amounts dictated by the chemistry calculator link also provided above) until calcium falls into line. After that, once both parameters are balanced, you can begin using Kalk (or even two-part) to keep your levels balanced.

 

 

Just be advised, though, while dosing Kalk with your top off is balanced, it is not guaranteed to be sufficient. That is, if your tank's consumption exceeds what you're putting in, your numbers will drop (but in a balanced way). If the consumption is less than what's being added, your numbers will climb in the same manner. Periodic testing of your levels should give you more insight into what your system demands.

[Origami]

And, yes, Kalk will help you maintain your alk levels, too.

 

Here's the chemistry:

 

Kalk powder is Calcium Hydroxide, or CaOH. When you mix it with water, it dissociates into a Calcium and a hydroxide ion:

 

CaOH ==>> Ca + OH

 

The hydroxide (OH) then reacts with carbon dioxide (CO2) that is dissolved in the water to form a bicarbonate (HCO3) ion:

 

OH + CO2 ==>> HCO3

 

At high pH (say, above 9.0 or so) carbonate (CO3) begins to dominate (become more plentiful than) bicarbonate. (This is simplified, of course. Actually CO2, HCO3, and CO3 (carbonate) are present simultaneously in differing amounts at most all times. )

 

Bicarbonate and carbonate make up the bulk of what we call alkalinity in the hobby. And, because of the reactions listed above, CaOH (kalk) gives us both calcium and alkalinity - a twofer!