Measuring Magnesium

Onoma1

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12 Aug 2018
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Rochdale
Having spent my chemistry lessons at the back of the class I am struggling to understand how to evaluate the quality of my water to understand what people on the forum mean when they say high or low. I wondered if anyone could provide a link to a baseline or advice.

The four levels are:

Magnesium 4.66 mg Mg/l
Manganese <4.48
Iron <37.1
Calcium 9.42

In particular I am interested in understanding whether or not I need to increase my magnesium and iron levels and wether or not they relatively high or low. Equally is tge calcium level enough for shrimp or do I need to add cuttlefish.

I think that the levels in my (soft) tap water are already in the reasonably high range and that frequent water changes with a general fertilizer should maintain them.

The unusual interest in this area was spurred on by a desire to grow buce successfully.
 

dw1305

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Hi all,
Magnesium 4.66 mg Mg/l
Manganese <4.48
Iron <37.1
Calcium 9.42
Is the unit for managanese (Mn) and iron (Fe) microg/L (ppb)?

If you look at the conductivity reading on the report it will give you a bit of an idea, but less than 200 microS. would be my guess. Have a look at <"Water report, do I have...">

You can't easily measure the level of any the metal ions, although any analytical lab. could do it with an <"ICP or AAS"> (this is what the water company would use).

I'd be tempted to add a bit more magnesium (Mg), there isn't really a down-side, same with the calcium, either add a little more via a cuttle bone or oyster shell chick grit, or CaCl2 if you want a known level.

It is always going to be guess work in the tank, which is why I like to use plant health and conductivity as a proxy for nutrient level. Because Bucephalandra species are slow growing it is going to take a while for deficiency symptoms to show, which is the advantage of using a floating plant with a quicker response (like Limnobium) as your "Canary".

cheers Darrel
 

rebel

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Ideally I'd say you need to dose both Ca and Mg to bring them up to 30ppm and 10ppm respectively. Suggest Seachem equilibrium or a DIY gH booster at 2/3 dose.
 

Onoma1

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12 Aug 2018
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Location
Rochdale
Thanks for your responses. I have bought TNC GH Boost to add to the water, and have added more info below about the water provided by the local water authority:

Conductivity: Min: 71.0 Average 135 Max 167 uS/cm at 20oC

Hardness Total as CaCO3 Min 23 Average 43 Max 53 mg CaCO3/l

Iron Min <2.15 Average <37.1 Max 1110 µg Fe/l

Magnesium Min 1.04 Average 4.66 Max 6.23 mg Mg/l

Manganese Min <0.510 average <4.48 Max 62.6 µg Mn/l

Does anyone have any advice or comments about the quality of the water for Buce or any other comparisons to base line my water?

Interestingly the Iron and Manganese amounts exceeded the regulatory amounts on at least one occasion (Manganese the regulatory max is 50 and the Iron is 200) from 39 samples. A number of the feeder streams that flow into the reservoir that provides my water are known as the 'iron waters' as the stones in them are covered with an orange deposit and they flow with a orange sediment/ coloration after heavy rain. The moorland surrounding the reservoir contains old mines (anthracite) and shale spoil heaps (grown over).
 
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rebel

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Looks fine for Buce and all aquatic plants. I would just fertilise using any method including EI if using high light or CO2. Otherwise 1/10 EI for the Buce tank with hardness as above.
 

dw1305

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Hi all,
Interestingly the Iron and Manganese amounts exceeded the regulatory amounts on at least one occasion (Manganese the regulatory max is 50 and the Iron is 200) from 39 samples. A number of the feeder streams that flow into the reservoir that provides my water are known as the 'iron waters' as the stones in them are covered with an orange deposit and they flow with a orange sediment/ coloration after heavy rain. The moorland surrounding the reservoir contains old mines (anthracite) and shale spoil heaps (grown over).
That almost certainly is the source of the iron (Fe) and managanese (Mn). Iron is a really common element in rock and soil, but normally it is as insoluble compounds.

If you have rocks containing iron pyrite (FeS2), and it is exposed to the air, it will weather (oxidise) to Fe2+ + 2SO42- + 2H+ and the resulting low pH acidic water will solubilise other compounds. When you have heavy rain (or where you get discharge from mine drainage) this water will run down into the reservoirs and eventually into the water supply.

There is a good summary in <"Environment Agency: Abandoned mines and the water environment">.

cheers Darrel
 
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