High dKH and low Ca/Mg

[FrostyKevin]

Any advice on increasing Mg and Ca without increasing dkH?
dkH: 12.7 (Hanna)
Mg: 1185 (Salifert)
Ca: 280-290 (Salifert)
Salinity: 1.023 (Hanna)

 

[Reefering1]

Is this a running tank with coral in it? What numbers are your targeting? How did you get to 12.7dkh? I would add Ca to lower dkh, then raise Mg above 1300, then raise salinity to 1.026 and see where you stand.

 

[FrostyKevin]

A few frags. I want to boost Ca to around 450 and Mg to 1400. I accidentally added too much all 4 reef. What brand of two part dosing do you recommend?

 

[Randy Holmes-Farley Verified Community Expert]

I don't see how those values can be accurate unless you have been adding a ton of alk and not calcium.

 

[Pod_01]

I don't see how those values can be accurate unless you have been adding a ton of alk and not calcium.

In the post 3 op states that he overdosed TM All For Reef.

I accidentally added too much all 4 reef.

But I don’t understand how he can have elevated Alk but no Calcium since All For Reef has both.

Maybe testing error….
‍

 

[Reefering1]

Maybe the calcium precipitated out(?) I would think the dkh would precipitate out 1st though... maybe some kind of ph supplement was added(?) Seems that pics of tank and more details of what has been dosed is required

A few frags. I want to boost Ca to around 450 and Mg to 1400. I accidentally added too much all 4 reef. What brand of two part dosing do you recommend?

 

[Randy Holmes-Farley Verified Community Expert]

Overdosing (or underdosing) all for reef cannot explain these results. I do not believe they are accurate, especially calcium.

 

[Randy Holmes-Farley Verified Community Expert]

Maybe the calcium precipitated out(?) I would think the dkh would precipitate out 1st though... maybe some kind of ph supplement was added(?) Seems that pics of tank and more details of what has been dosed is required

They can only precipitate together, at 2.8 dKH of alk consumed for each 18-20 ppm of calcium consumed.

 

[Reefering1]

They can only precipitate together, at 2.8 dKH of alk consumed for each 18-20 ppm of calcium consumed.

Good to know!! So,hypothetically speaking, these numbers can only make sense if alkalinity was overdosed independently of Ca? (Or testing error)

 

[Randy Holmes-Farley Verified Community Expert]

Good to know!! So,hypothetically speaking, these numbers can only make sense if alkalinity was overdosed independently of Ca? (Or testing error)

Yes. Or maybe the low salinity plus alk dosing.

 

[FrostyKevin]

Overdosing (or underdosing) all for reef cannot explain these results. I do not believe they are accurate, especially calcium.

What would cause the Ca and Mg testing to be inaccurate? And more importantly, what can I do to fix it so that the tests are more accurate?

 

[Randy Holmes-Farley Verified Community Expert]

What would cause the Ca and Mg testing to be inaccurate? And more importantly, what can I do to fix it so that the tests are more accurate?

Bad reagents (expired, diluted, contaminated, mismanufactured, etc.), bad test protocol followed, bad test design. I have no idea which it might be.

Getting some confirmatory tests with a different kit is a good idea.

 

[FrostyKevin]

Bad reagents (expired, diluted, contaminated, mismanufactured, etc.), bad test protocol followed, bad test design. I have no idea which it might be.

Getting some confirmatory tests with a different kit is a good idea.

Would a 1.023 SG also contribute to a bad titration as some have suggested?

 

[hexcolor reef]

I was dealing with the same issue, what type of water are you using? tap, RO,???
also rocks will absorb calcium and magnesium as well.
What’s your PH? High ALK can through both out of wack. Make sure you have good air exchange in the room

All in all best thing to do is a water change to get balance chemistry. Adding calcium and magnesium no matter the amount will just continue to drop

 

[Randy Holmes-Farley Verified Community Expert]

Would a 1.023 SG also contribute to a bad titration as some have suggested?

Yes. Natural seawater at that sg would have calcium of 366 ppm.

 

[Randy Holmes-Farley Verified Community Expert]

I was dealing with the same issue, what type of water are you using? tap, RO,???
also rocks will absorb calcium and magnesium as well.
What’s your PH? High ALK can through both out of wack. Make sure you have good air exchange in the room

All in all best thing to do is a water change to get balance chemistry. Adding calcium and magnesium no matter the amount will just continue to drop

I do not agree with that advice. Water changes are a more expensive and poorly successful way to boost calcium and magnesium.

 

[FrostyKevin]

Yes. Natural seawater at that sg would have calcium of 366 ppm.

Ok, the test kits are fairly new (about 2-3 months old), so expiration shouldn't be a problem. Do you think bumping SG to 1.025 at least before testing again would be a better idea?

 

[hexcolor reef]

I do not agree with that advice. Water changes are a more expensive and poorly successful way to boost calcium and magnesium.

a clear chemical imbalance the OP is dealing with.

They can only precipitate together, at 2.8 dKH of alk consumed for each 18-20 ppm of calcium consumed.

I’ve been battling high ALK while Calcium and Magnesium both were being used up or precipitating (calcium).
Went through a whole bottle of RedSea Mag/Calcium dosing. The only thing that fixed was two water changes so far. ALK Is down to 11 and Calcium/Magnesium more stable. Not having huge drops any more

 

[Randy Holmes-Farley Verified Community Expert]

Ok, the test kits are fairly new (about 2-3 months old), so expiration shouldn't be a problem. Do you think bumping SG to 1.025 at least before testing again would be a better idea?

I’d bump salinity to 35 ppt = 1.0264

 

[Randy Holmes-Farley Verified Community Expert]

a clear chemical imbalance the OP is dealing with.

I’ve been battling high ALK while Calcium and Magnesium both were being used up or precipitating (calcium).
Went through a whole bottle of RedSea Mag/Calcium dosing. The only thing that fixed was two water changes so far. ALK Is down to 11 and Calcium/Magnesium more stable. Not having huge drops any more

You used way more calcium and magnesium to boost them by water change, plus everything else in the salt mix. It’s just not economical and is far more work.