Where did all the Manganese go...?

Edgecrusher28 · Feb 27, 2023

The road that has brought me to this question was a quest to get some troubled zoanthid colonies to finally cheer up and enjoy life. Regardless if folks believe that certain trace element serve any real role in the reef tank or not remains up for grabs. However, I have noticed a reoccurring situation where through weekly ICP testing and dosing, several trace elements will remain undetectable until they are through the roof; for me this was iodine. On the other hand, I have trace elements that no matter what I've done over the last few months, continue to remain undetectable. For example, I have now gone through 100ml of Manganese over the last month or two and just got back last weeks test and; surprise surprise, its undetectable. So my question is, how can that even be possible? If consumption was truly this high then that means everyone's tank would be in a significant deficit without major dosing, Anyone run into a similar situation or know what's going that would cause these type of results?

Tank is 100gallon system.
ICP tests were ran through ATI.
ATI elements were used for dosing.

Thanks in advance!

Randy Holmes-Farley · Feb 27, 2023

Iron and manganese are consumed very rapidly. Only a few grams of new macroalgae can strip an entire reef tank of manganese.

Here's how that is determined.

This article shows that several macroalgae contain 50-100 mg/kg of manganese.

https://www.mdpi.com/2079-6374/12/5/359
100 gallons (379 L) of natural seawater (containing 0.17 ug/L of manganese) contains approximately 64 ug or 0.06 mg of manganese.

Thus, 1 kg of macroalgae containing 100 mg of manganese contains as much manganese as 1,666 aquariums of natural seawater.

Thought of differently, 1 gram of the macroalgae contains 0.1 mg of manganese, which is still more than an entire 100 gallon aquarium of natural seawater.

Miami Reef · Feb 27, 2023

I dose 165 ng/L (typical ocean value, but it varies) with a DIY manganese solution once a week.

I never did an ICP, but I wouldn’t be surprised if it was still undetectable.

Edgecrusher28 · Feb 27, 2023

Randy Holmes-Farley said:
Iron and manganese are consumed very rapidly. Only a few grams of new macroalgae can strip an entire reef tank of manganese.

Here's how that is determined.

This article shows that several macroalgae contain 50-100 mg/kg of manganese.

https://www.mdpi.com/2079-6374/12/5/359
100 gallons (379 L) of natural seawater (containing 0.17 ug/L of manganese) contains approximately 64 ug or 0.06 mg of manganese.

Thus, 1 kg of macroalgae containing 100 mg of manganese contains as much manganese as 1,666 aquariums of natural seawater.

Thought of differently, 1 gram of the macroalgae contains 0.1 mg of manganese, which is still more than an entire 100 gallon aquarium of natural seawater.

Interesting, but with that said I cant say that I've seen any depreciable difference in the corals or in the algae growing in the turf scrubber with all the addition of Manganese. Would it make any sense to continue dosing?

Thanks for the informative reply!

Randy Holmes-Farley · Feb 27, 2023

Edgecrusher28 said:
Interesting, but with that said I cant say that I've seen any depreciable difference in the corals or in the algae growing in the turf scrubber with all the addition of Manganese. Would it make any sense to continue dosing?

Thanks for the informative reply!

Every photosynthetic organism in the tank uses it, but it may be they get enough from foods. Here's my comment from my own testing:

Manganese (Mn). Triton can just barely detect the natural level of manganese (0.17 µg/L) since their LOD is 0.12 µg/L. Detecting none suggests it may be depleted, and is another possibility for dosing, but I have less confidence that this one is really seriously depleted since it is so close to the LOD. But Mn is biologically important and I will consider it.