Low Ca

[JulesH]

Hi,

I am in need of some assistance with my 3.5 year old mixed reef tank. For the last three months I have been unable to get a viable Ca reading from my Salifert test kit. It always changes blue at the start of the test indicating I have a ridiculously low Ca reading.

I have been really reticent to change anything in my tank as it looks visually good, and there is all round growth. Its mainly LPS with some plating montiporas and your bulk standard sticks like Forest fire, Bali slimer etc.

I have no obvious precipitation of Ca in the sump, I have a separate power head in the sump to ensure the Part 1 and 2 are well mixed.

I have a 300 litre tank with a 3 litre water change every day.
My parameters:

SG - 1.026
Alk - 9.33
Mg 1355

I use Reef zlements P1 and 2 and I dose about 34ml per day of both solutions.
My dosing pump is not blocked, or cables spilt.

Perhaps the test kit is spoilt or I should do a ICP?

If I had extremely low levels of Ca how would my tank inhabitants reacted?

Confused,

Julian

 

[KrisReef]

How are you making up calcium Alk, and mag in your tank?

I suspect the test kit is the source of error if everything looks ok after 3 months of "bad" tests?

 

[JulesH]

Hi Kris,

Its a commercially available part 1 and 2, and on my second batch over the last few months.

How are you making up calcium Alk, and mag in your tank?

I suspect the test kit is the source of error if everything looks ok after 3 months of "bad" tests?

 

[EnterName]

I would get another test kit just to make sure. If your readings are still off with the new test kit, you can think about an ICP test.

I'm not familiar with zlements but 34mL in 300L correspond to 1.13dKH alkalinity and 8.2mg/L calcium if I understood their guide correctly. It's very well possible that your calcium consumption is higher than your alkalinity demand and you need to compensate for that. Calcium and alkalinity are not always consumed equally fast so you will need to refer to the linked guide on what to do. I assume you will need to increase the dosage of Part 2 which seems to be the calcium containing solution. Alternatively you might be able to use Calcium chloride (Component A of typical balling solutions) to bring Calcium back to the required levels.

 

[Randy Holmes-Farley]

Try the kit on new salt water.

Also, try adding less than the initial 0.6 mL. That way you may be able to see the color change with less titrant, indicating low calcium.

 

[JulesH]

This morning I tried my test kit on some new salt water, Tropic Marin Pro reef.

It is a Salifert test kit so, I added the 2ml of water to the plastic test tube, added the Ca 1, magenta powder via the supplied spoon. The water turns blue before I add the Ca 2 reagent?

I tried the test again and got the result of 0.76 equating to 120 ppm of Ca.

Third test, 0.77 equating to 115 ppm of Ca.

I shall take a water sample up to my LFS to see what results he gets?

I see two options, the test kit is kaput or my salt mix is kaput. Surely if my salt is not good then I would be looking at tank Armageddon?

This has been an issue for about three months now, I spend a month at sea at a time, when I get back my tank looks better, all the more for me leaving it alone.

 

[Randy Holmes-Farley]

I have not followed the changing Salifert directions so cannot comment on whet6her that is exactly correct or not. Hopefully others can.

But assuming it is correct, I expect it is a kit issue rather than a hugely off batch of salt.

 

[JulesH]

Thanks Randy, the Salifert tests are pretty easy. If I could not carry out a Salifert Ca test properly I perhaps should not be reef keeping!

 

[JulesH]

Thanks Randy, the Salifert tests are pretty easy. If I could not carry out a Salifert Ca test properly I perhaps should not be reef keeping!

Mars bar fingers and small keypad, sorry disregard!

 

[JonasRoman]

Hi,

I am in need of some assistance with my 3.5 year old mixed reef tank. For the last three months I have been unable to get a viable Ca reading from my Salifert test kit. It always changes blue at the start of the test indicating I have a ridiculously low Ca reading.

I have been really reticent to change anything in my tank as it looks visually good, and there is all round growth. Its mainly LPS with some plating montiporas and your bulk standard sticks like Forest fire, Bali slimer etc.

I have no obvious precipitation of Ca in the sump, I have a separate power head in the sump to ensure the Part 1 and 2 are well mixed.

I have a 300 litre tank with a 3 litre water change every day.
My parameters:

SG - 1.026
Alk - 9.33
Mg 1355

I use Reef zlements P1 and 2 and I dose about 34ml per day of both solutions.
My dosing pump is not blocked, or cables spilt.

Perhaps the test kit is spoilt or I should do a ICP?

If I had extremely low levels of Ca how would my tank inhabitants reacted?

Confused,

Julian

Low ca down to at least 300 is not a problem even if its ofcourse not beneficial. Ofcourse this is something you just have to fix, and its math, just dose Cacliumchloride dihydrate separate until you reach 400. Yo can raise ca approx 50 ppm each day, so you will quick be back on track.
To measure Ca is super easy, and all titration tests are good as long as they are not contaminated. You do not have to send ICP for such an easy task. Just buy a new Ca test , and I suggest not salifert as they with their new design can not go below 300 (see my explanations below). In your case its good to know exact your value to estimate how far you have to go. /Jonas

 

[JonasRoman]

I have not followed the changing Salifert directions so cannot comment on whet6her that is exactly correct or not. Hopefully others can.

But assuming it is correct, I expect it is a kit issue rather than a hugely off batch of salt.

The new with salifert is that they have the NaOH (or maybe another base) together with the titrant EDTA, so you need to add approx 0.6 ml before its enough with NaOH to make the colour dye work. 0.6 ml EDTA in salifert correspinds to approx 300 ppm Ca, so test cant therefore never measure below 300. If ca is above 300, the sample will turn from light blue to red at 0.6 ml of this mixed reagent, then it works as normal. I cant see any benefts with this more than its 1 liquid bottle instead of 2, not a obvious improvement as they still have the powder separate. I think (my guess) this was a 2 step adaptation to some machines that require only liquids, but the development stopped there.

 

[JonasRoman]

This morning I tried my test kit on some new salt water, Tropic Marin Pro reef.

It is a Salifert test kit so, I added the 2ml of water to the plastic test tube, added the Ca 1, magenta powder via the supplied spoon. The water turns blue before I add the Ca 2 reagent?

I tried the test again and got the result of 0.76 equating to 120 ppm of Ca.

Third test, 0.77 equating to 115 ppm of Ca.

I shall take a water sample up to my LFS to see what results he gets?

I see two options, the test kit is kaput or my salt mix is kaput. Surely if my salt is not good then I would be looking at tank Armageddon?

This has been an issue for about three months now, I spend a month at sea at a time, when I get back my tank looks better, all the more for me leaving it alone.

This confuses me. Salifert doesnt change colour until you have added 0.6 ml (approx) independent of ca value, as its need 0.6 ml to get the color dye to work. With this said, its impossible to detect Ca values below 300 with salifert test. With the old design you could though.

example 1: You have 400 ppm in ca. When you add reagent liquid, sampel is blue and turn red approx wen you have added 0.6 ml. Not before becasue it needs some NaOH to start to work. After this 0.6 ml its turning red and NOW it works as a normal test and you can titrate down to it turns blue again.

example 2: You have 290 ppm in ca. When you add reagent liquid, sampel is blue and still blue when you have added 0.6 ml becasue you have already passed the end titration point. And its no way to detect titration point below 300 becasue before 0.6 ml you have not NaOH enough to make it work.

Reason is that the colour dye needs to be in a base with pH 11-12 . Reason is 2: the dye needs a base environemtne to work at all(at least pH 9), and also we need that high pH (11-12) to remove Mg that will be as MgOH and hense out of the equation. Most Ca test has the NaOH separate (bottle 1) meaning that titration works from Ca 0-eternal. In the new "design" salifert has NaOH in same bottle as EDTA titrant, making this force to add 0.6 ml before it starts to work. And then you are already at 300 ppm ca approx.

 

[JonasRoman]

Try the kit on new salt water.

Also, try adding less than the initial 0.6 mL. That way you may be able to see the color change with less titrant, indicating low calcium.

no, that wil not work, see my explanations here how salifert is designed:-)
/Jonas

 

[gbroadbridge]

This morning I tried my test kit on some new salt water, Tropic Marin Pro reef.

It is a Salifert test kit so, I added the 2ml of water to the plastic test tube, added the Ca 1, magenta powder via the supplied spoon. The water turns blue before I add the Ca 2 reagent?

I tried the test again and got the result of 0.76 equating to 120 ppm of Ca.

Third test, 0.77 equating to 115 ppm of Ca.

I shall take a water sample up to my LFS to see what results he gets?

I see two options, the test kit is kaput or my salt mix is kaput. Surely if my salt is not good then I would be looking at tank Armageddon?

This has been an issue for about three months now, I spend a month at sea at a time, when I get back my tank looks better, all the more for me leaving it alone.

The salifert Ca kit instruction changed recently. Are you using the correct instructions that came with the kit?
And have you read them or are you doing what you used to do with an older kit?