Magnesium Issues with testing...

[EgotisticObeseChihuahua]

Two weeks ago, I ran out of 2-part magnesium mix for my tank. I ordered some but it took 2 weeks to come in, I also failed to test my water during those 2 weeks.
Until today I got my magnesium and mixed it in a jug furthermore testing my water. The results are as follows:

current levels: Alkalinity:8.9Dkh Levels two weeks ago:11 Dkh
current levels: Calcium: 440ppm Levels two weeks ago:420ppm
current levels: Magnesium: ??? Levels two weeks ago:1550ppm

I am having trouble testing for magnesium, I used two different tests (Hanna magnesium) + (Salifert Magnesium test kit)
Both read the max amount: Salifert read over 1500, whilst Hanna read over 1800. My hammer corals have been shrinking a little bit.
I have only done 2 water changes within the two weeks with Reef Crystals salt.

Can the reagent expire early? Its date is for 08, 2027.

 

[blaxsun]

It's entirely possible you have a high magnesium level. If you've run two different test kits and they're both maxing out I'd be inclined to exclude testing error.

 

[EgotisticObeseChihuahua]

It's entirely possible you have a high magnesium level. If you've run two different test kits and they're both maxing out I'd be inclined to exclude testing error.

DO you think I should wait and see if it goes down?

 

[bushdoc]

Magnesium is easy to overdose as consumption it's much lower than Calcium. It will take several weeks (depending on your coral density) for magnesium to drop, so if you are observing some negative effects do water change(s). You could also dilute sample and then test, this would give you more accurate result.

 

[EgotisticObeseChihuahua]

Magnesium is easy to overdose as consumption it's much lower than Calcium. It will take several weeks (depending on your coral density) for magnesium to drop, so if you are observing some negative effects do water change(s). You could also dilute sample and then test, this would give you more accurate result.

OK, thanks judging from past tests magnesium gets taken out pretty fast at around 10-20 ppm per day. Will one 20 gallon water change be enough per week on my 120? To stabilize everything.

 

[bushdoc]

You would have to do some math:

• first establish current level of Magnesium by testing diluted sample ( let's say 50% dilution)
• find out what is magnesium level in freshly mixed saltwater you want to use to do water changes
• For example if Mg is very high, lets say over 2000ppm and your newly mixed saltwater Mg content is 1400ppm, than one water change of 20 gal ( for 120gal tank) would drop Mg to about 1900ppm, second water change of 20 gal would drop it to about 1816ppm and so on

 

[blaxsun]

DO you think I should wait and see if it goes down?

Mine is also over 1500. I'm just letting it decline naturally (and I know above 1500 isn't ideal).

 

[homer1475]

Back in the day we used to combat bryopsis with a certain magnesium product. We used to go as high as 1800 with 0 issues to any corals.

High magnesium is not the issue with your corals, unless it's crazy high.

I would dilute your sample by half, test, then multiply the result by 2 to get an accurate reading.

 

[homer1475]

EDIT:
Double post!

 

[EgotisticObeseChihuahua]

You would have to do some math:

• first establish current level of Magnesium by testing diluted sample ( let's say 50% dilution)
• find out what is magnesium level in freshly mixed saltwater you want to use to do water changes
• For example if Mg is very high, lets say over 2000ppm and your newly mixed saltwater Mg content is 1400ppm, than one water change of 20 gal ( for 120gal tank) would drop Mg to about 1900ppm, second water change of 20 gal would drop it to about 1816ppm and so on

OK, once I get home from work I will dilute a test and find out my magnesium.

 

[Seansea]

Magnesium consumption can depend on the tank. If u have an algae scrubber and alot of soft corals your magnesium consumption can be high. Not sure what kind of tank u have but it could come down on its own if you have gsp growing wild and algae scrubber soaking it up.

 

[EgotisticObeseChihuahua]

Magnesium consumption can depend on the tank. If u have an algae scrubber and alot of soft corals your magnesium consumption can be high. Not sure what kind of tank u have but it could come down on its own if you have gsp growing wild and algae scrubber soaking it up.

I have GSP but it has not taken off yet. I also have a refugium would that help?

 

[Randy Holmes-Farley Verified Community Expert]

OK, thanks judging from past tests magnesium gets taken out pretty fast at around 10-20 ppm per day. Will one 20 gallon water change be enough per week on my 120? To stabilize everything.

That cannot be anything other than test error or a salinity drop.

Real magnesium consumption is 1/10th of the calcium decline, or lower. 0-1 ppm per day is typical. 10 ppm per day is not possible.

 

[Randy Holmes-Farley Verified Community Expert]

Magnesium consumption can depend on the tank. If u have an algae scrubber and alot of soft corals your magnesium consumption can be high. Not sure what kind of tank u have but it could come down on its own if you have gsp growing wild and algae scrubber soaking it up.

I do not believe soft corals consume much magnesium.

Magnesium consumers are primarily coralline algae, and some hard corals. It has to be deposited as some form of calcium/magnesium carbonate to be consumed. Coralline is higher than many hard corals since it deposited a high magnesium calcite, but still uses 10x as much calcium.

 

[Randy Holmes-Farley Verified Community Expert]

I have GSP but it has not taken off yet. I also have a refugium would that help?

No, GSP do not consume any magnesium.

 

[Seansea]

I do not believe soft corals consume much magnesium.

Magnesium consumers are primarily coralline algae, and some hard corals. It has to be deposited as some form of calcium/magnesium carbonate to be consumed. Coralline is higher than many hard corals since it deposited a high magnesium calcite, but still uses 10x as much calcium.

Doesnt anything with cloryphyll consume magnesium? Gsp growing rapidly with all the algae in it i woukd think would chew it up. Same with any rapid growing algae. I know in my tank it gets chewed up way faster than alk or calcium and my testing is accurate. Confirmed with icp

 

[Randy Holmes-Farley Verified Community Expert]

Doesnt anything with cloryphyll consume magnesium? Gsp growing rapidly with all the algae in it i woukd think would chew it up. Same with any rapid growing algae. I know in my tank it gets chewed up way faster than alk or calcium and my testing is accurate. Confirmed with icp

Not really, no. If the magnesium concentration inside of the organism is not higher than the magnesium concentration in the seawater, then the organism actually contributes a tiny bit to raising the level of magnesium outside of it by taking up proportionally more water than magnesium.

The magnesium concentration in seawater is about 1300 ppm.

Chlorophyll is a large molecule that weighs 37.2 times as much as the magnesium ion it contains, so to have as much magnesium in chlorophyll inside the algae as magnesium outside, it would need to contain 37.2 x 1300 ppm = 48,370 ppm of chlorophyll, or about 5% of its wet weight.

This paper shows that algae have chlorophyll ranging from 3-60 mg/L = 3-60 ppm.

Estimation of the Chlorophyll-A Concentration of Algae Species Using Electrical Impedance Spectroscopy

Algae are a significant component of a biological monitoring program in an aquatic ecosystem. They are ideally suited for water quality assessments because of their nutrient requirements, rapid reproduction rate, and very short life cycle. Algae composition and temporal variation in abundances...

www.mdpi.com

Other papers give similarly low values for chlorophyll:

Identification of carotenoids and chlorophylls from green algae Chlorococcum humicola and extraction by liquefied dimethyl ether

In this study, the microalga Chlorococum humicula was evaluated as a potential source of carotenoids and chlorophylls, and extraction of these pigment…

www.sciencedirect.com

Rin Shimek tested caulerpa, xenia, and a leather coral (sarcophyton) for various ions, including magnesium.

https://reefkeeping.com/issues/2002-12/rs/feature/index.php

While I do not know how accurate his testing was, caulerpa actually excluded magnesium and its proportion in the caulerpa was 797 +/- 491 ppm.

Xenia was very close to neutral to magnesium, with 1600 +/- 566 ppm, and he tested one leather coral at 1800 ppm.

FWIW, leather corals do contain calcium carbonate spicules that also contain some magnesium.

Calcite Formation in Soft Coral Sclerites Is Determined by a Single Reactive Extracellular Protein

Calcium carbonate exists in two main forms, calcite and aragonite, in the skeletons of marine organisms. The primary mineralogy of marine carbonates has changed over the history of the earth depending on the magnesium/calcium ratio in seawater during ...

www.ncbi.nlm.nih.gov

Soft corals contain small spicules of calcium carbonate called sclerites, which are biomineralized structures composed of an organic matrix and a mineral (calcite) fraction. Calcite crystals, as shown in this study, are secreted on an organic matrix and then are transported to the outside of the cell for subsequent extracellular calcification in a process similar to sclerite calcification in the gorgonians . Mature sclerites are completely free of cellular materials and ultimately become extracellular structures.​

 

[EgotisticObeseChihuahua]

Not really, no. If the magnesium concentration inside of the organism is not higher than the magnesium concentration in the seawater, then the organism actually contributes a tiny bit to raising the level of magnesium outside of it by taking up proportionally more water than magnesium.

The magnesium concentration in seawater is about 1300 ppm.

Chlorophyll is a large molecule that weighs 37.2 times as much as the magnesium ion it contains, so to have as much magnesium in chlorophyll inside the algae as magnesium outside, it would need to contain 37.2 x 1300 ppm = 48,370 ppm of chlorophyll, or about 5% of its wet weight.

This paper shows that algae have chlorophyll ranging from 3-60 mg/L = 3-60 ppm.

Estimation of the Chlorophyll-A Concentration of Algae Species Using Electrical Impedance Spectroscopy

Algae are a significant component of a biological monitoring program in an aquatic ecosystem. They are ideally suited for water quality assessments because of their nutrient requirements, rapid reproduction rate, and very short life cycle. Algae composition and temporal variation in abundances...

www.mdpi.com

Other papers give similarly low values for chlorophyll:

Identification of carotenoids and chlorophylls from green algae Chlorococcum humicola and extraction by liquefied dimethyl ether

In this study, the microalga Chlorococum humicula was evaluated as a potential source of carotenoids and chlorophylls, and extraction of these pigment…

www.sciencedirect.com

Rin Shimek tested caulerpa, xenia, and a leather coral (sarcophyton) for various ions, including magnesium.

https://reefkeeping.com/issues/2002-12/rs/feature/index.php

While I do not know how accurate his testing was, caulerpa actually excluded magnesium and its proportion in the caulerpa was 797 +/- 491 ppm.

Xenia was very close to neutral to magnesium, with 1600 +/- 566 ppm, and he tested one leather coral at 1800 ppm.

FWIW, leather corals do contain calcium carbonate spicules that also contain some magnesium.

Calcite Formation in Soft Coral Sclerites Is Determined by a Single Reactive Extracellular Protein

Calcium carbonate exists in two main forms, calcite and aragonite, in the skeletons of marine organisms. The primary mineralogy of marine carbonates has changed over the history of the earth depending on the magnesium/calcium ratio in seawater during ...

www.ncbi.nlm.nih.gov

Soft corals contain small spicules of calcium carbonate called sclerites, which are biomineralized structures composed of an organic matrix and a mineral (calcite) fraction. Calcite crystals, as shown in this study, are secreted on an organic matrix and then are transported to the outside of the cell for subsequent extracellular calcification in a process similar to sclerite calcification in the gorgonians . Mature sclerites are completely free of cellular materials and ultimately become extracellular structures.​

Dang, you really know your stuff. Thanks for the help.

 

[Randy Holmes-Farley Verified Community Expert]

Dang, you really know your stuff. Thanks for the help.

lol Thanks and Happy Reefing.

 

[Seansea]

Havent read it all but interesting but i can only speak on my tank. If the testing is correct which it appears to be then something is consuming magnesium pretty good. I dose a4r which has some magnesium but i also have to dose a magnesium supplement to the toon of about 30 ml every few days. The only things really growing in my tank are algae from the scrubber which i harvest every 10 days or so, the gsp out of control on its rock island, montiporas and of course corraline. Something is chewing it.