# Calcium Dosing Procedure



## dwalstad

Below is the procedure that we worked out (see earlier page of thread below) for increasing the GH using calcium chloride and magnesium sulfate. This procedure is faster and better than adding oyster grit to the filter. It shouldn't increase the pH.

This procedure is designed for very softwater aquariums where GH = 0- 6 and plants aren't doing well)

Steps in Procedure:​

Measure starting GH of your aquarium water

Prepare concentrated solutions of each chemical (MgSO4 and CaCl2)

Add a small portion of Mg solution to the aquarium and measure resulting GH increase

Add Mg solution until you get about what you want (I'd recommend a GH increase of about 1-2, no more)

Then start adding the Ca solution until you get a GH increase that is 4X that of the increased GH due to Mg

The final GH should be over 6, preferably around 8

http://www.aquaticplantcentral.com/forumapc/el-natural/21205-wet-thumb-forum-calcium-dosing-increase-3.html?highlight=Equilibrium


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## snowy

Thanks for providing that info, the water in our area is quite soft so this is good to know. I have been using shellgrit in the sump of the filter on one tank and adding a commercial mix of mineral salts intended for hardening RO water to another, but this is a much more accurate and predictable way to do it.


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## DataGuru

So is someone going to sticky it?
Or perhaps make a sticky with links to good threads like this one?


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## dwalstad

Betty,

Excellent question! You are welcome to pursue this. Otherwise, I and others will continue resurrecting important posts like this one.

The calcium chloride dosing procedure will probably go into the next printing of my book. I've heard several justifiable complaints that the oyster grit procedure is too slow and/or raises the pH.

Diana


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## fish n' chris

Greetings, 

Would anyone care to offer information on a source for Calcium Chloride as described on this thread? Many thanks for your assistance.

Fish N' Chris


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## dennis

Aquarium Plants, Aquatic Plants, Planted Aquariums, and Aquarium Plant Fertilizer He carries all the dry chemicals useful to our hobby. The prices are very good and he is a good guy and a long standing supporter of the planted tank hobby. He carries several kinds of Ca sources, the easiest one to use is CaCl2+2H2O. CaCO3 is OK but does not dissolve easily (less than 1g per liter) CaCl2+2H2) dissolves much easier. The Cl should not hurt anything in the levels you would be introducing it.

Coincidentally, I was just figuring out a reference solution to calibrate your test kit using CaCl2+2H2O.

Step 1.
Dissolve 1.31g CaCl2+2H2O in 500ml distilled H2O
This yields a solution with 714.4mg/l Ca.
There are 7.144 mg/l Ca in 1 degree Gh
So, your solution has a value of 100 degrees

Step 2.
Dilute 10ml solution with 90ml distilled H2O.
This makes a 10% solution so its value is 10 degrees.

Step 3.

Test this dilute solution with your test kit.
If the reading is not 10 degrees, divide 10 by your reading and this is the factor your kit is off. 
Example: you get 8 using the 10 reference solution.
10/8=1.25 so if you test your aquarium and get 6 degrees, you actually have 6*1.25= 7.5 degrees


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## DataGuru

There are several commercial products made out of CaCl.
Ice melter is one. They also sell it as a GH increaser at pool stores. Some farm stores may sell it as well.

The APC fertilator should be a good reference for how much an amount of either CaCl or Mag Sulfate will increase GH. I think if I'm reading it correctly, 
1 tsp of CaCl 6H20 will increase calcium hardness by about 22ppm in 10 gallons of water. 
1 tsp of MgSO4 H2O will increase magnesium hardness by about 13ppm in 10 gallons of water.

so you'd need a ratio of 2/1 calcium chloride to mag sulfate to get the 4 to 1 ratio Diana talks about earlier.


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## cana

> The APC fertilator should be a good reference for how much an amount of either CaCl or Mag Sulfate will increase GH. I think if I'm reading it correctly,
> 1 tsp of CaCl 6H20 will increase calcium hardness by about 22ppm in 10 gallons of water.
> 1 tsp of MgSO4 H2O will increase magnesium hardness by about 13ppm in 10 gallons of water.
> 
> so you'd need a ratio of 2/1 calcium chloride to mag sulfate to get the 4 to 1 ratio Diana talks about earlier.


Thanks. I agreed that this is the best way to get the 4 to 1 ratio.


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## 01krisp10

Excuse my lack of knowledge on this subject, but what procedure should be used to maintain the KH along with this method of raising the GH? Or will KH additives always raise pH?

Also when you say oyster grit, are you including Florida Crushed Coral Aragonite Formula?


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## DataGuru

adding calcium chloride and mag sulfate only affect GH (general hardness).

Other minerals like crushed coral, crushed oystershell, aragonite, etc, dissolve over time and increase both GH (calcium and magnesium) and KH (bicarbonates). Whether you need to buffer your source water depends on the KH in the tap water. Typically abking soda (sodium bicarbonate) increases KH which increases pH. Unlike in regular tanks, I don't think KH drops over time in a NPT.


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## david f

To Diana ,and Folks

regarding the procedure,of calcium/magnesium dosing ,I have been trying to find suitable CaCl for water hardness,but an agricultre company here in N.Z says ,that CaCl/MgSo4 are (not compatiable for dairy cows) ,would it still be O.K to use this form of CaCl been a common fertiliser or a swimming pool store CaCl.



Many Thanks ,David N.Z.


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## rohape

This caught my eye in the sticky section. I was interested in it because of my snails. They need calcium for their shells. For those of you that haven't seen my posts, I love my snails, and I have A LOT of them. 
I use "calcium disks" that I make from plaster of paris. It is Calcium Silicate. I know this isn't an exact science as what was described to reach an optimal GH, it's more of a willy nilly science.  I use these all the time, mainly because of the high demand of my snails. 
Would this method work to keep your GH high? I also use calcium pills from the local Walgreens.
I use DAP plaster of paris, and its VERY easy.
Just thought I would put in my two cents as an option if this is viable. I would be interested in any feedback. 
Thanks!


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## newbie314

I use crushed eggshells - CaCO3 - Ca for the plants and animals, CO3 for the buffer and the plants (supplement for CO2).

Funny snails are mentioned. As soon as I drop it, the snails seem to eat it (or they are eating the left over membrane). I think I've even seen snail poop that was white. Maybe they are eating too much of a good thing.

Does pooped CaCO3 disolve fast


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## bencozzy

calcium chloride can be hard on some plant species if your having to dose it regularly.

im using calcium sulfate, for my snail and shrimp tanks with no ill effects on the plants or animals. the animals actually are looking better.


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## Diana K

I have used Oystershell grit, sold for small caged birds. I only use this in tanks where I want both KH and GH to come up a bit. I prepare the water change water to match the tank, though, not wait for the grit to dissolve (it dissolves very slowly). It is there to keep thing stable in case the pH starts to drop. I think I have just about the same amount now as I had a few years ago when I first opened the box. It seems not to dissolve. I think this suggests that my Lake Tanganyika tanks are pretty stable and might not even need it. 

I have used cuttlebone as a source of minerals for Apple snails, it dissolves so slowly that it does not seem to affect GH or KH. I know it can, it is just not a problem in my tanks. Small piece of cuttlebone, large tank...


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## dawntwister

Rohape I have a question concerning DAP plaster of paris you used. Did you put it in before or after fish introduced to the tank. Did you mix it into the substrate?


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## rohape

Oh, none of those. I make "cookies" with it. It's for my snails. This is in an established aquarium. If you want more in depth info just PM me.


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## david f

Hi everyone,


I have not been on for a while but still have a great interest with my fish keeping.
(This is a topic of a little confusion for me and I would really like to know how I can dissolve calcium carbonate in water.)Quote from wikipedia calcium carbonateeople with hard water have a problem with lime scale.water from under ground aquifiers etc, as drinking water,can be exposed to higher levels of Co2 than the normal atmosphere,(it is my under standing Co2 will dissolve calcium carbonate at higher concentrations)Over time the water from the tap will out gas the Co2 and cause this (preciption) or lime scale.So that tells me that soft water like what I have in my Tap has very little Co2, and does not dissolve the CaCo3 that I add.Poeple with hard water must have the same problem with there (lime scale) at the tap or kettle.( Co2 loss from water cause CaCo3 to become poorly soluble.

So does hard water become softer water over time because of the loss of Co2?


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## rohape

It's been a while, but I read the same thing on Wikipedia. The following is merely speculation.
I don't know that it really dissolves in water, but that it is consumed.....which leads me to wonder now "how" it is consumed.
I know my snails scrape at the crushed shells I have. But now for the plants, how do they obtain the calcium if I'm not dosing CO2 to help in the dissolution. 
I think hardwater becomes softer because of the absorption of the metals.
Hmm, good questions and points.


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## david f

tap water for use in my aquarium is very soft water.we have many under ground springs all around our area and is my only source to use .I need to raise the pH from 5.5 using a couple of calcium carbonate tablets and vinger to balance the sudden raise.after about a week or so the chlorine has gone GH is about 25ppm and KH much the same,but still very soft water ,with a pH way up to 8.0 if I don't use enough vinger .I use a 200 Ltr plastic drum to prepare all this .I might start to use a little soil water ,Brackish minerals for Cichlids and (marine calcium reactor?)just to give the water a little more life for the ecosystem???


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## cholly

Coming from reef aquariums, calcium is one subject I've spent a lot of time on. CaCl is regularly sold as a one-part calcium additive for reef tanks (and thus not preferred; the two-part products that also maintain dKh are much better for that purpose), so if anyone is having a hard time finding it you can just buy it off the shelf. One such product:

http://www.drsfostersmith.com/product/prod_display.cfm?c=3578+4680+14057+16827&pcatid=16827

Anyone consider using kalkwasser powder as an alternative though?


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## dwalstad

Dear David F,

I'd be careful here.

Firstly, please don't use vinegar to bring pH down. You may get a bacterial bloom (cloudy water), as the acetic acid in vinegar is like fastfood for bacteria. Unfortunately, I recommended vinegar in my book's first edition-- a mistake. You should be able to add a little calcium carbonate so that it brings the GH up to a suitable level (I would aim for GH = 6-8 ). If you "overshoot", just dilute with tapwater. I find that the pH gradually stabilizes within NPTs without having to do anything.

Secondly, if your GH and KH are 25 ppm, then your water is now very, very hard. However, you state that your water is "still very soft". That can't be, and I can't tell from your letter whether your water is now very soft or very hard.

With soft water, you have many choices. You could:


add a commercial products designed to harden softwater and/or RO water ("reef salts" for cichlid tanks would probably work) 
follow the "Calcium Dosing Procedure" outlined in this thread
stick with your calcium carbonate tablets, but also add a little magnesium and potassium


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