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Heavyd

Dosing Magnesium - Bluebolt style

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Heavyd

I went a bought some Magnesium Sulphate from Bunnings.

It’s called Manutec Epsom Salts – water soluble.

Basically, I want to gradually increase the Magnesium in my tank as some of my CRS have lost some colour/thickness of colour and some die after moulting. Alll other parameters, diet etc look good including Calcium levels.

This tank has a gH of 6, Calcium levels of 40ppm, Magnesium levels of 1.75. Ca:Mg ratio of 22.9:1. So to me it looks like Magnesium is a limiting factor in this tank and possibly causing problems.

Following from Bluebolts post, he mentions that he increase concentration by 0.5 ppm at a time. I would like to emulate this in one of my tanks to see how it goes.

From the MSDS, it states that the Magnesium Sulphate is in hydrated form with a molecular weight of 246.47. So this to me works out as MgSO4.7H2O. Anyone correct me if I’m wrong.

This works out to be around 10.14% Magnesium, which the packet confirms pretty much on the front as 9.6% w/w.

So if I were to take 1g (1000mg) of this product and put it in 100litre tank, that would equate to 10mg/Litre increase = 10ppm?

Since the Magnesium makes up roughly 10% of the product, that would equate to 1ppm increase of Magnesium when dosing 1g of product in 100 litres of water?

So to do as BB does, I should add 0.5 gram of product to increase Magnesium ppm by 0.5?

Sorry for the long, boring blah blah blah, but I really don’t want to stuff this up.

Comments please.

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mr_c265

Are you sure the Magnesium level is 1.75ppm? And not 1.75 degrees or something? (never used a magnesium test kit)

Basically yes, your calculations are right though. I tend to use Human Grade Magnesium Sulphate though, but i'm sure it is fine.

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Heavyd

I have calculated the Magnesium value in ppm using the equation provided by BB:

Formula to calculate Mg & Ratio

1. Get your GH Value (dGH)

2. Get your Ca Value (ppm)

3. Mg = ((GH*17.86) - (Ca*2.5)) /4.1

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fishmosy

I have some reservations about using epsom salts (magnesium sulfate) to boost magnesium levels in shrimp tanks. On several fish forums there have been some debates over the long term effects of sulfates (e.g. laxative) on fish health. And as we know, shrimp can be much more sensitive than fish.

From what I have read, magnesium carbonate is a better option for adding magnesium ions to water in aquariums and has the additional bonus of providing more carbonate ions which are used by shrimp to grow their shell/skeleton. However I admit that I have no first hand experience with using either magnesium sulfate or magnesium carbonate in shrimp tanks. It may be that the carbonate ions might have much different effects in boosting GH and KH than sulfate ions so may be less useful in shrimp tanks. Another question is availability, is magnesium carbonate readily available? I dont know as I haven't tried to aquire it.

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Heavyd

Thanks for your input fishmosy. I had reservations as well, but have been reassured that if done correctly there is no problems with the sulphates in the water. I guess the issue with the carbonates as you've mentioned are the effects they have on kH values and pH. Not really desirable for sensitive shrimp.

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jayc

So if I were to take 1g (1000mg) of this product and put it in 100litre tank' date=' that would equate to 10mg/Litre increase = 10ppm?

[/quote']

What does 1g equate to in Tablespoon measurement? Sorry, I'm used to Tablespoon measurements rather than weight.

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Heavyd

Not too sure about tablespoon, but I think on the packet it says 2 teaspoons is roughly 10 grams.

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fishmosy
Thanks for your input fishmosy. I had reservations as well, but have been reassured that if done correctly there is no problems with the sulphates in the water. I guess the issue with the carbonates as you've mentioned are the effects they have on kH values and pH. Not really desirable for sensitive shrimp.

Very true. Are there any other alternatives to sulfates?

Hmmm. Nitrates? Not unless you have rampant plant growth and massive water changes as in planted (EI and CO2) tanks. Not really conducive to the keeping of shrimp. chloride? Maybe but might cause problems with TDS/EC. Citrate? Probably not as it would probably lower pH. Oxide? No, combines with water to form hydroxide and magnesium hydroxide is not very soluble. I can't think of any others that would be readily available.

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fishmosy
Not too sure about tablespoon' date=' but I think on the packet it says 2 teaspoons is roughly 10 grams.[/quote']

Yeah 1 teaspoon is roughly equivalent to 5grams.

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jayc

Teaspoon measurement is fine, I'm familiar with that as well.

Wait a minute ... my maths is sooooo bad.

But,

If as you say, "1g (1000mg) of this product and put it in 100litre tank, that would equate to 10mg/Litre increase = 10ppm"

1gm of MgSO4 in 100L = 10ppm

then isn't 0.5gm = 5ppm??

You'd want to dose less if my maths is correct.

Unless you mean 0.5 milligram.

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Heavyd
Teaspoon measurement is fine' date=' I'm familiar with that as well.

Wait a minute ... my maths is sooooo bad.

But,

If as you say, "1g (1000mg) of this product and put it in 100litre tank, that would equate to 10mg/Litre increase = 10ppm"

1gm of MgSO4 in 100L = 10ppm

then isn't 0.5gm = 5ppm??

You'd want to dose less if my maths is correct.

Unless you mean 5 milligram.

0.5g=5ppm of Epsom salts, but Magnesium only comprises 10% of that, so 0.5gm Epsom salts = (10% of 5ppm)=0.5ppm. Does that sound right?

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jayc

Ok. That sounds right, I forgot Mg was only 10%.

Wouldn't it be easier to mix 1gm of Epsom Salts into a 500ml water bottle and add 5ml everyday until the bottle was empty?

That's what I do.

Get a syringe from the chemist, if you haven't already got one.

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Heavyd
Very true. Are there any other alternatives to sulfates?

Hmmm. Nitrates? Not unless you have rampant plant growth and massive water changes as in planted (EI and CO2) tanks. Not really conducive to the keeping of shrimp. chloride? Maybe but might cause problems with TDS/EC. Citrate? Probably not as it would probably lower pH. Oxide? No' date=' combines with water to form hydroxide and magnesium hydroxide is not very soluble. I can't think of any others that would be readily available.[/quote']

Not too sure about alternatives with the shrimp.

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Heavyd
Ok. That sounds right' date=' I forgot Mg was only 10%.

Wouldn't it be easier to mix 1gm of Epsom Salts into a 500ml water bottle and add 5ml everyday until the bottle was empty?

That's what I do.

Get a syringe from the chemist, if you haven't already got one.[/quote']

That sounds like a good idea. I was just trying to make sure I had the maths correct before I started dosing. The actual tank in question is a 200 litre tank. I used 100 litres for the example as it's easy to work with.

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jayc
That sounds like a good idea. I was just trying to make sure I had the maths correct before I started dosing. The actual tank in question is a 200 litre tank. I used 100 litres for the example as it's easy to work with.

I'd still go with your original 1gm calculation.

Always go slow. Measure at regular intervals to ensure we have not overshot the 4:1 ratio.

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Heavyd
I'd still go with your original 1gm calculation.

Always go slow. Measure at regular intervals to ensure we have not overshot the 4:1 ratio.

Would take months at that rate, and then have to factor in water changes as well. Although I definitely dont want to rush things either.

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jayc

You could probably do 10ml per day into 200L of water safely.

Test after every 5 days.

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BlueBolts

Great discussion, I've asked Oli (Mr_Docfish) to comment on this thread, as he's the expert, and can advise accordingly. :)

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Heavyd

I was waiting for you to chime in BB. I would love to know what the safest dosage is based on experience. And also the frequency.

The helpful advise that Jayc has provided would see it taking more than half a year to correct the Magnesium deficiency.

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BlueBolts
This tank has a gH of 6' date=' Calcium levels of 40ppm, Magnesium levels of 1.75. Ca:Mg ratio of 22.9:1. So to me it looks like Magnesium is a limiting factor in this tank and possibly causing problems.[/quote']

Do double check your Ca level.....Ratio of 23:1 is HUGE....if you're using Salty Shrimp/RO, then Ca imbalance with Mg doesn't equate, alternatively perhaps you're dosing additional Ca ? Even so, 23:1 with GH 6, and presumably TDS <200 doesn't register in my minute knowledge of WP.

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Heavyd
Do double check your Ca level.....Ratio of 23:1 is HUGE....if you're using Salty Shrimp/RO' date=' then Ca imbalance with Mg doesn't equate, alternatively perhaps you're dosing additional Ca ? Even so, 23:1 with GH 6, and presumably TDS <200 doesn't register in my minute knowledge of WP.[/quote']

I will double check my Calcium levels. TDS is around 175. The only other thing I'm dosing is Mineral powder.

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BlueBolts

Using RO/Salty Shrimp ?

[TABLE=width: 199]

[/TD]

API Ca Test kit

20ml

Bottle 1 - 10 Drops

[TD=colspan: 3]Bottle 2 - 1 Drop - 5ppm

[/TABLE]

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Heavyd

Yep, using Saltyshrimp exclusively.

I'm using the Salifert Calcium test kit. A bit more involved to test for Calcium.

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Heavyd

I thought I should add the following taken from the web:

"1dGH = 17.86 ppm CaCO3 and 7.143 ppm Ca2+"

Following from this, to maintain a gH of say 5 whilst maintaining a ratio of Ca:Mg of 4:1

Would give us 28.6ppm Ca : 7.1ppm Mg

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jayc

The helpful advise that Jayc has provided would see it taking more than half a year to correct the Magnesium deficiency.

No problem. Yes it will seemingly take ages but that's because you have a huge ratio gap between Ca and Mg to fill.

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