Low Alk and High Calcium - how to correct

[stoneroller]

I'm still not convinced the test is accurate, but assuming it is, ....

Hanna has calibration standards for ALK. Buy some and use them routinely.

 

[Randy Holmes-Farley Verified Community Expert]

Actually he said calcium was 500+, because 500 is the upper limit of most hobby kits, so we don’t know how much above 500 actually is.

Calcium: 500+ppm (this is the top of the scale on the RS Test Kit - it was within a drop or two of changing color)

That puts it at 500-520 ppm or so.

The scale is linear and one can use as many drops or syringes as needed to get to the endpoint with any calcium kit.

 

[Randy Holmes-Farley Verified Community Expert]

Hanna has calibration standards for ALK. Buy some and use them routinely.

Which standard are you referring to?

I presume you mean the OP, not me. I do alk with a standard acid titration that needs no calibration.

 

[WallysWorld]

Actually he said calcium was 500+, because 500 is the upper limit of most hobby kits, so we don’t know how much above 500 actually is.

I did another test of Ca. This time after the first 1ml syringe of titrant (chemical C in the Red Sea test kit) I filled the syringe and continued with titrant until I reached the neutralization point (color change). If I can extrapolate linearly beyond the maximum limit printed on the test kit the Ca is at 800 ppm.

 

[biom]

Yes it was expected that’s why is good to do some more water charges. Luckily you have relatively small tank and will be easier.

 

[Randy Holmes-Farley Verified Community Expert]

I did another test of Ca. This time after the first 1ml syringe of titrant (chemical C in the Red Sea test kit) I filled the syringe and continued with titrant until I reached the neutralization point (color change). If I can extrapolate linearly beyond the maximum limit printed on the test kit the Ca is at 800 ppm.

You can always use more syringes and add the values together. If calcium is 800 ppm, then I agree that water changes to lower it are good.

If you do not know how it got this high, however, I'm suspicious of the result. It would not be easy.

 

[Randy Holmes-Farley Verified Community Expert]

Yes it was expected that’s why is good to do some more water charges. Luckily you have relatively small tank and will be easier.

Based on what he wrote it wasn't expected. Either his first statement or his second test were wrong. Both cannot be right.

But I do agree that if the calcium is 800 ppm (seems very odd without a massive overdose of calcium supplement) that water changes are the best way forward.

 

[biom]

Based on what he wrote it wasn't expected. Either his first statement or his second test were wrong. Both cannot be right.

But I do agree that if the calcium is 800 ppm (seems very odd without a massive overdose of calcium supplement) that water changes are the best way forward.

Yes, it was expected
If you are dosing 16 ml per day calcium instead of normal 5 ml per day without dosing alkalinity in a month or so, then I would expect more than 500 ppm (if the normal was 450)

My Alk is low and Calcium is high. What should I do to correct this? Is it as simple as changing the dosing amount on my pump? I have been dosing Red Sea A, B, and C on separate pumps in the following quantities for at least 7-8 months with no changes:

Red Sea KH/Alk 11 ml/day
Red Sea Ca+ 5 ml/day
Red Sea Mg 2 ml/day
Red Sea NO-POx 3 ml/day

All dosed several times per 24 hour period (above are total daily amounts)

My tank is 37 gallons, I've had it running for 2 years, and it has been very stable until recently, say the last month or so. Alk has been around 7 dKH and calcium around 450ppm. I'm also curious as to what possibly has changed.

Parameters from todays measurement:
Temp: 78.2F
Salinity: 35 ppt
Ph: 7.77
Alk 3.7 dKH
Calcium: 500+ppm (this is the top of the scale on the RS Test Kit - it was within a drop or two of changing color)
Magnesium: 1300 ppm
Nitrate: 1ppm
Phosphate 0.07 ppm

Thanks in advance for advice

 

[WallysWorld]

Thanks guys for all the help here! I will proceed with more than normal water changes to get tank parameters closer to normal.

And yes I was dosing 16ml of Ca+ per day (11 ml on the Alk channel plus 5 on the Ca channel), this had been going on for over a month. Good news is that I haven't lost any coral - yet!

Thanks again!

 

[stoneroller]

Which standard are you referring to?

I presume you mean the OP, not me. I do alk with a standard acid titration that needs no calibration.

Right, the OP should use a standard to ensure his Hanna is accurately measuring ALK. I should have noted that.

 

[Randy Holmes-Farley Verified Community Expert]

Yes, it was expected
If you are dosing 16 ml per day calcium instead of normal 5 ml per day without dosing alkalinity in a month or so, then I would expect more than 500 ppm (if the normal was 450)

Not going to debate what you expected. lol

 

[biom]

Not going to debate what you expected. lol

Not sure I get the joke, maybe I dont express myself correctly in English, apologies

Additional dosing 330 ml of calcium supplement in 37 gallons of water will raise the Ca level with 471 mg/l on top of the normal 450 mg/l resulting in 921mg/l Ca which is pretty close to WallysWorld's result (800 mg/l) having in mind some abiotic precipitation probably took place. So I dont see why I or somebody else should not expect Calcium is much more than 500?

Thanks guys for all the help here! I will proceed with more than normal water changes to get tank parameters closer to normal.

And yes I was dosing 16ml of Ca+ per day (11 ml on the Alk channel plus 5 on the Ca channel), this had been going on for over a month. Good news is that I haven't lost any coral - yet!

Thanks again!

It is great you haven't lost any coral. Finger crossed. Luckily you overdosed Calcium, not Alk which could be far more dangerous.

 

[Randy Holmes-Farley Verified Community Expert]

Again, it's not worth a fight, but I will clarify what I meant.

Not sure I get the joke, maybe I dont express myself correctly in English, apologies

Additional dosing 330 ml of calcium supplement in 37 gallons of water will raise the Ca level with 471 mg/l on top of the normal 450 mg/l resulting in 921mg/l Ca which is pretty close to WallysWorld's result (800 mg/l) having in mind some abiotic precipitation probably took place. So I dont see why I or somebody else should not expect Calcium is much more than 500?

Certainly, yes. Once you know that he double dosed calcium, one expects it to be high.

He also said that "Calcium: 500+ppm (this is the top of the scale on the RS Test Kit - it was within a drop or two of changing color) "

If what he wrote was literally true, it is neither consistent with 800 ppm calcium, nor with a good solution to an alk problem being a water change. On his retest he changed this statement to a much higher value for calcium, making a water change a good approach (assuming the second calcium test is correct).