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GH - Ca:MG Ratio


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General Hardness (GH) is the measurement of the level of dissolved minerals our water contains, which is predominantly represented by calcium & magnesium, but also contains other mineral ions.

GH does influence PH like KH, and there’s no direct co-relation to KH. It is critical to the health of shrimps. GH can affect the function of internal organs and hinder proper growth as well as affect egg fertility and hinder breeding capacity. Shrimps may adapt to survive in different GH levels, but will encourage issues with breeding.

GH is especially important to shrimp because Calcium Carbonate is vital in a shrimps molting cycle and growth. Shrimps grow by sheding their existing smaller exoskeletons every so often to grow a newer and bigger one. For a successful moult, it is very important for them to have enough calcium carbonate present in the water for them to absorb and to create a strong and healthy new shell in the molting process. Any GH deficiencies, wont allow them to create a strong enough shell to properly fend off diseases, infections, and stress and will eventually die. Calcium Carbonate also helps in food digestion and absobtion, and assist the immune system to fight toxins, and diseases in the body and can reduce overall stress in your shrimps.

Magnesium is the key to unlocking Calcium Carbonates potential. It is able to make Calcium absorbable in shrimps bodies. Without it they would suffer from lack of calcium. It is needed for a healthy calcium absorbtion and balance as well as healthy muscles and nervous system.

The ratio of GH:MG for shrimps is generally a 4:1 to 3:1 (Calcium:Magnesium)

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

i.e.

1. If GH is 4 dKH

2. If Ca is 20 ppm

3. Mg = ((4 x 17.86) - (15 x 2.5)) / 4.1 = 5.23

Therefore - Ca:Mg is 20:5.23, approx. 3.8:1

GH

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The API Ca Test Kit Instructions..

[TABLE=width: 199]

[TABLE=width: 199]

5ml

Bottle 1 - 10 Drops

[TD=colspan: 3]Bottle 2 - 1 Drop - 20ppm

[/TABLE]

[/TD]

[/TD]

[/TABLE]

If your Ca is <20ppm, instead of a 5ml, a 20ml can be used, thus...

[TABLE=width: 199]

[TABLE=width: 199]

20ml

Bottle 1 - 10 Drops

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

[/TABLE]

[/TD]

[TD]

[/TABLE]

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I use CaS04 to increase my Calcium levels, and MgSO4 (Epsom Salts) for my Magnesium Levels. There are also many Ca booster products, like the Shirakura Ca+ etc... Alternatively, to reduce Ca/Mg, WC with RO water.

Experimenting with these ratio's does have it's issues......dosage needs to be gradual, i.e. 0.5ppm per day etc...., and really for the more experienced hobbyist, who like to tinker.

Most products like Salty Shrimp, Seachem Equilibrium etc...have these ratios, so there really is no need for adjustments, unless there'a a specific (i.e. higher) level of GH you want to attain. In these situations, adding just a CaSO4, without taking into account the Ca:Mg ratio will create issues as mentioned above for the shrimps.

Please use this article as a reference guide to understand GH, and the Ca:Mg ratio. If you plan to "tinker", do your research, "measure twice, cut once", to ensure there's no bad experiences etc...., and ALL is done accordingly.

:sleeping:

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Absolutely awesome write up BB, this definitely has to be a sticky. You always write up the best articles, they are so informative & thorough, thanks for the info dude :encouragement:

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Awesome!

I'm a tinkerer, so this info is great.

The ratios are different for fish, and as BB said critical to get right.

I mix my "tonic" in a bottle and slowly add drops into the tank until the desired GH.

I've seen shrimp "dance" (swim mid water) in reaction. Have you noticed a similar reaction?

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Thanks so much for spending the time to write this up BB. I have wondered about the ratios before and wasn't too sure about it.

I'll definitely be referring back to this. Now to go and purchase a Calcium test kit......

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Ok, I went off and bought a new gH test kit (Sera brand) and a Calcium test kit (Salifert brand).

I tested two of my tanks and my results definitely don't fit within the guidelines above.

Tank 1:

gH=5, Calcium=30

From the Equation above the ratio of Ca:Mg is 8.6:1

Tank 2

gH=8, Calcium=45

From equation ratio is 6.1:1

Both tanks have Saltyshrimp minerals used at every water change and occasional application of mineral powder (Benibachi/Mosura).

So BB, do I need to add Epsom salts to correct the ratio??

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The 1st & foremost question is how your shrimps are going, breeding well, good shrimplets survival rate, colour to it's best potential, if its YES to all the above, then I wouldn't change a thing. There are so many factors influencing WP, and health/well being of a shrimp, and sometimes by changing thins balance, it may disrupt the equilibrium of your tank.

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Well I would say that Tank 1 has good shrimplet survival rate, BUT I feel that the colour in some shrimp could be solidified.

Tank 2 has average shrimplet survival rate but the colour seems better in general.

I guess that I would most like to improve the solidity of the colour in Tank 1. Is it ok to buy any Epsom Salts? i.e the ones from the chemist? How much would I dose in a 110 litre tank?

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Hi BB thanks for that great write up! Just wondering how much does the dosage raise TDS?

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Well I would say that Tank 1 has good shrimplet survival rate' date=' BUT I feel that the colour in some shrimp could be solidified.

Tank 2 has average shrimplet survival rate but the colour seems better in general.

I guess that I would most like to improve the solidity of the colour in Tank 1. Is it ok to buy any Epsom Salts? i.e the ones from the chemist? How much would I dose in a 110 litre tank?[/quote']

My dosing regime consists of premixing separately calcium sulfate and magnesium sulfate into 500ml of water (RO or rain water) stored in separate old water bottles (those Mt Franklin ones).

Come every other water change time, I drop the appropriate ratios into the change water with a syringe. The effect is slow so as to not shock the livestock in the tank. Calcium is constantly used up. So you will need to continue dosing calcium, just double dose the magnesium until you get closer to a 4:1 ratio.

Also, be careful when purchasing Epsom salts from chemists/pharmacists. Being a non gardening store they generally stock Epsom Salts as "bath salts" and may contain perfumes or other additives for that sort of application. Just make sure there is nothing else added.

I get my Magnesium sulfate MgSO4 (Epsom Salts) from gardening stores or bunnings where not additives are not included. It's a fertiliser, so look for it in the gardening section.

As another caution - You need to be careful as to which compound you use to introduce the calcium ions. If calcium comes in with chlorine as Calcium Chloride (a very common calcium additive sold at the LFS), when the calcium decides to hook up with the OH or carbonate ions, Chlorine is left behind as a byproduct. Increased chlorine ions are not particularly a good thing to have in our tanks.

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What is everyone's thoughts on the amount of Calcium for a healthy freshwater tank?

I've read that it should be 100ppm.

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Is it ok to buy any Epsom Salts? i.e the ones from the chemist? How much would I dose in a 110 litre tank?
As jayc stated' date=' you'll need to ensure the Epsom Salts hasn't got any additives. I bought mine from Bunnings....EPSOM SALTS (Magnesium Suplphate)
Hi BB thanks for that great write up! Just wondering how much does the dosage raise TDS?
It will raise TDS, depending on dosage/tank size...best to conduct your own experiment.
What is everyone's thoughts on the amount of Calcium for a healthy freshwater tank? I've read that it should be 100ppm.
100ppm = 100/17.9 = 5.6dH, sounds perfect. Between 4-6 is ideal. I had my tanks @4 dH, but increasing to 5-6 over the next few weeks.Just repeating ... this thread is not intended to create "Mad Scientist" out of us, it's intended for use as a reference. Salty shrimp, and other remineralise products would have the Ca & Mg ratio/level. Although they do get depleted, regular WC with remineralised water etc, would get this ratio balance. I check my ratio's every 3-4 months ONLY, and will make the neccesary adjustments, usually 1/2 a pinch of Mg in a 200lt system, so not much at all....
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Just repeating ... this thread is not intended to create "Mad Scientist" out of us' date= it's intended for use as a reference. Salty shrimp, and other remineralise products would have the Ca & Mg ratio/level. Although they do get depleted, regular WC with remineralised water etc, would get this ratio balance. I check my ratio's every 3-4 months ONLY, and will make the neccesary adjustments, usually 1/2 a pinch of Mg in a 200lt system, so not much at all....
Agreed.When I said I dose during every other water change above, it's usually only small drops of each into the water.Don't over do it people.
100ppm = 100/17.9 = 5.6dH, sounds perfect. Between 4-6 is ideal. I had my tanks @4 dH, but increasing to 5-6 over the next few weeks.
There you have it. You'll find lots of sources on how to increase calcium or how to increase GH. Or lots of sources for Marine/Salt water tanks. But you won't find much info on how much Calcium to increase in a freshwater tank. You saw it first on SKF.So if you have a Calcium test kit, aim for 100ppm ... like with anything, increase it slowly.
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  • 4 weeks later...
  • 1 month later...

im still new to shrimp. i never check my shrimp tank gh and kh...as its only about 1.5 week now. how ever i found my crs died about 4 of them. i just think that because ammonia as i keep with guppies and platy fry.

btw can i know where to buy CaS04? and tester for GH ?

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im still new to shrimp. i never check my shrimp tank gh and kh...as its only about 1.5 week now. how ever i found my crs died about 4 of them. i just think that because ammonia as i keep with guppies and platy fry.

btw can i know where to buy CaS04? and tester for GH ?

Read this supplementary post.

http://www.shrimpkeepersforum.com/forum/showthread.php/4404-Why-the-need-for-Calcium-amp-Magnesium

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Nope, I tend to work with individual ferts myself, so I know exactly what goes in the tanks.

But that product makes it simpler for a lot of people.

Just make sure you get a GH test kit as well, and test as you add the product.

You can add half the recommended dosages on the packet to be safe as well.

Never increase GH too quickly, otherwise your shrimp will suffer.

Not sure what ratio of Potassium is in that product, but that's good for a planted tank.

As long as it's not too much. If you have lots of plants, it's ok. But if your tank is only mosses, then you don't want too much.

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I have 25 L nano fish tank, did test the GH is 7, and the KH is 4, PH is 7.2. what best gh and kh for red cherries and crystal red. and also how much I need to put CASO4 and magnesium sulphate? PS: im using tap water as cant install RO Water on rent place. thanks for help

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  • 1 month later...

I overheard from my friend who is also a shrimphobbiest in Japan that high GH disturb shrimp's molting and that could lead to death.

Has anyone has any info on this? :confused-new:

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Poetic winter any good LFS will sell ro water if thats the path you want its only 25c a litre get a 10-15 litre water container from bunnings and do it that way.

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