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MagicJ

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Jul 11, 2011
9,651
3,761
Hobart, Tasmania
Randy's Recipe - Maintaining Calcium, Alkalinity And Magnesium
Maintaining a stable water environment is one of the key requirements of successfully maintaining a reef aquarium.

This post discusses a relatively cheap method of maintaining calcium, alkalinity and magnesium which are three key elements in salt water and are critical in keeping many corals, especially Small Polyp Stony (SPS) corals. The author, Randy Holmes-Farley is an American chemist who has been keeping reef aquariums for over 15 years and has authored many reefkeeping articles with a chemistry emphasis.

Rather the paste the original article I have summarised/extracted the main sections below, and converted measurements etc to Australian standards. However, I would recommend that anyone contemplating using this 'recipe' read the full article which was published in Reefkeeping Online Magazine in February 2006 and can be found here.

Why
I can't answer this better than Randy ;)
Calcium and alkalinity are supplied to reef aquaria in order to balance the losses caused by the formation of calcium carbonate. This formation takes place in hard corals to form their skeletons, and in other internal structures such as spicules in certain soft corals. It also takes place in a wide range of other organisms, ranging from coralline algae to snails to clams. Deposition of calcium carbonate also takes place outside of biological systems, such as on heaters and pump impellers, where the increased temperature results in decreased solubility of calcium carbonate, and hence a greater likelihood of precipitation.

In each of these cases, what is being deposited is largely calcium carbonate. Since calcium and carbonate are present in pure calcium carbonate at exactly equal concentrations (one ion of calcium to one ion of carbonate), the removal rate of calcium and carbonate by all of the mechanisms described above should be the same. To a great extent, aquarists use alkalinity as a surrogate measure of carbonate (and bicarbonate). The exact balance between calcium and carbonate demand in a reef aquarium is therefore equally well described as a balance between calcium and alkalinity demand.

Reef aquarists take great advantage of the 1:1 matching of calcium and alkalinity demand in reef aquaria by using additives that supply calcium and alkalinity in this same ratio. In this way, over- or under-dosing of such balanced calcium and alkalinity additives should not result in skewing the aquarium water's chemistry toward too much calcium and too little alkalinity, or too much alkalinity and too little calcium. On the other hand, independent additions of calcium and alkalinity, even with careful and frequent measurement, often lead to such imbalances.

There exist a variety of such balanced additives. They include calcium carbonate/carbon dioxide (CaCO3/CO2) reactors, limewater (kalkwasser), the two part additive systems, and some one-part systems. As a class, I strongly recommend them over any other unbalanced additive method for most reef aquarists.
This quote was sourced from here.

Here is a great video which discusses the various methods of maintaining calcium and alkalinity and some recommendations as to when to use them.

What

In Australia we use three commonly available, and relatively cheap, products which are available from your local supermarket and/or hardware store.

For calcium, Damprid

damprid.jpg


For Alkalinity, Baking Soda (not Baking Powder as this contains other products)

awww2.woolworthsonline.com.au_Content_ProductImages_big_075201.jpg


and for Magnesium, Epsom Salts

awww2.woolworthsonline.com.au_Content_ProductImages_big_348284.jpg


You will also need some measuring cups and scales, 9 litres of RO water and 3 x 3 litre storage containers - plastic juice bottles are ideal but make sure they are well cleaned before use.

The 'recipe' is scalable - if you need twice as much then just double the quantities.
Calcium and Alkalinity supplements can also be obtained from your local pool supply company - just check the level of purity to ensure it is safe to put in your valuable aquarium ;).

Part 3A uses magnesium chloride hexahydrate which improves the quality of the mix and reduces the build-up of sulfate in the aquarium. This is not readily available in Australia, although if you try hard you will find some of a suitable quality and price. Many people have been using Part 3B i.e. just using Epsom Salts, successfully for many years and, whilst not ideal, has led to no ill effects in their aquarium. The build-up of sulphates can be mitigated by regular water changes which is part of our normal maintenance schedule. More information on this issue is available in the original article.

How

This article actually details two primary recipes. One uses raw baking soda, and the other uses baking soda that aquarists bake before use. The baking drives some of the carbon dioxide out of the baking soda, and raises its pH as well as its alkalinity.

Recipe #1 is for use in reef aquaria whose pH is normal to low. In practice, more reef aquarists end up choosing this recipe than Recipe #2. It will tend to raise pH due to its alkalinity part's elevated pH, as do most of the commercial two-part additives. The increase in pH depends on the aquarium's alkalinity and, of course, on how much is added. Adding on the order of 0.5 meq/L of alkalinity increases the pH by about 0.3 pH units immediately upon its addition (and even higher, locally, before it has a chance to mix throughout the aquarium).
If you are using limewater (kalkwasser) and the aquarium is at pH 8.4 or above, this recipe is not the best choice. Otherwise, it is likely to be a good option. It is twice as concentrated as Recipe #2, because the baking process makes the baking soda more soluble.

Recipe #2 is for use in reef aquaria whose pH is on the high side (above 8.3 or so). It will have a very small pH lowering effect when initially added. The pH drop achieved will depend on the aquarium's alkalinity and, of course, on how much is added. Adding on the order of 0.5 meq/L of alkalinity drops the pH by about 0.04 pH units immediately upon its addition.
If you are using limewater (kalkwasser) and the aquarium is at pH 8.4 or above, this recipe may be the best choice. It is half as concentrated as Recipe #1 because the raw baking soda is less soluble because it's unbaked.

Recipe #1

In this recipe three stock solutions are made. Two are used frequently, and one is used only occasionally to balance other elements not added in the first two. The solutions can be mixed and stored in any plastic or glass container, and they will last indefinitely.

Recipe # 1, Part 1: The Calcium Part
Dissolve 396 grams of calcium chloride dihydrate (Damprid) in enough water to make 3 litres of total volume. You can dissolve it in about 1 litre of water, and then pour that into the 3 litre container and fill it to the top with more freshwater. This solution has about 29,000 ppm calcium.

Note that the solution will get quite warm when dissolving the calcium chloride.

Recipe #1, Part 2: The Alkalinity Part
Spread 470 grams of baking soda on a baking tray and heat in an ordinary oven at 300°F (150°C) for one hour to drive off water and carbon dioxide. Overheating is not a problem, either with higher temperatures or longer times. Dissolve the residual solid in enough water to make 3 litres total. This dissolution may require a fair amount of mixing. Warming it speeds dissolution. This solution will contain about 1,500 meq/L of alkalinity (4,200 dKH). Be sure to NOT use baking powder. Baking powder is a different material that often has phosphate as a main ingredient.

Once these two solutions are created, they can be added as frequently as necessary to maintain calcium and alkalinity. For further dosing instructions, see below.

Recipe #1, Part 3: The Magnesium Portion
The magnesium portion gives us two options, with Part 3A being preferred from an aquarium chemistry standpoint. Pick one and follow the same dosing directions regardless of which version you select.

Recipe #1, Part 3A
Dissolve Epsom salts (2.4 cups) and magnesium chloride hexahydrate (4 cups) in enough purified freshwater to make 3 litres total volume. There will likely be a precipitate that forms even if you fully dissolve both ingredients separately. That precipitate is calcium sulfate (calcium as an impurity in the magnesium chloride and sulfate from the Epsom salts). It is fine and appropriate to dose the precipitate along with the remainder of the fluid by shaking it up before dosing.
This solution is added much less frequently than the other two parts. Each time you finish adding 3 litres of both parts of Recipe #1, add 485 mL (2 cups) of this stock solution. You can add it all at once or over time as you choose, depending on the aquarium's size and set up. Add it to a high flow area, preferably a sump. In a very small aquarium, or one without a sump, I suggest adding it slowly.

The first time it's added, I recommend adding just a small portion and making sure there isn't any problem (such as corals closing up due to stress) before adding the remainder. Make sure corals and other organisms don't get blasted with locally high concentrations of the main ingredients or impurities, or else they may become stressed. This solution contains about 37,300 ppm magnesium, 55,500 ppm sulfate and 68,000 ppm chloride.

Recipe #1, Part 3B
Dissolve 1.4kg of Epsom salts (about 6.3 cups) in enough purified freshwater to make 3 litres total volume. This solution is added much less frequently than the other two parts. Each time you finish adding 3 litres of both parts of Recipe #1, add 485 mL (2 cups) of this stock solution. It can be added all at once or over time as you choose, depending on the aquarium's size and set up. Add it to a high flow area, preferably a sump. In a very small aquarium, or one without a sump, I suggest adding it slowly.
The first time it's added, I recommend adding just a small portion and making sure there isn't any problem (such as corals closing up due to stress) before adding the remainder. Make sure corals and other organisms don't get blasted with locally high concentrations of the main ingredients or impurities, or else they may become stressed. This solution contains about 37,250 ppm magnesium and 148,000 ppm sulfate.

Recipe #2

In this recipe three stock solutions are created. Two are used frequently, and one is used only occasionally to balance other elements not added in the first two. The solutions can be mixed and stored in any plastic or glass container.

Recipe #2, Part 1: The Calcium Part
Dissolve 200 grams (about 1 cup) of calcium chloride dihydrate (Damprid) in enough water to make 3 litres of total volume. You can dissolve it in about 1 litre of water, and then pour that into the 3 litre container and fill it to the top with more freshwater. This solution is about 14,700 ppm in calcium.

Note that the solution will get quite warm when dissolving the calcium chloride.

Recipe #2, Part 2: The Alkalinity Part
Dissolve 235 grams of baking soda (about 0.9 cups) in enough water to make 3 litres total. This dissolution may require a fair amount of mixing. Warming it speeds dissolution. This solution will contain about 750 meq/L of alkalinity (2,100 dKH). Be sure to NOT use baking powder. Baking powder is a different material that often has phosphate as a main ingredient.

Once these two solutions are created, they can be added as frequently as necessary to maintain calcium and alkalinity. For further dosing instructions, see below.

Recipe #2, Part 3: The Magnesium Portion
The magnesium portion again gives us two options, with Part 3A being preferred from an aquarium chemistry standpoint. Pick one and follow the same dosing directions regardless of which version you select.

Recipe #2, Part 3A
Dissolve Epsom salts (2.4 cups) and magnesium chloride hexahydrate (4 cups) in enough purified freshwater to make 3 litres total volume. There will likely be a precipitate that forms even if you fully dissolve both ingredients separately. That precipitate is calcium sulfate (calcium as an impurity in the magnesium chloride and sulfate from the Epsom salts). It is fine and appropriate to dose the precipitate along with the remainder of the fluid by shaking it up before dosing.
This solution is added much less frequently than the other two parts. Each time you finish adding 3 litres of both parts of Recipe #2, add 242 mL (1 cup) of this stock solution. You can add it all at once or over time as you choose, depending on the aquarium's size and set up. Add it to a high flow area, preferably a sump. In a very small aquarium, or one without a sump, I suggest adding it slowly.

The first time it's added, I recommend adding just a small portion and making sure there isn't any problem (such as corals closing up due to stress) before adding the remainder. Make sure corals and other organisms don't get blasted with locally high concentrations of the main ingredients or impurities, or else they may become stressed. This solution contains about 37,300 ppm magnesium, 55,500 ppm sulfate and 68,000 ppm chloride.

Recipe #2, Part 3B
Dissolve 1.4kg of Epsom salts (about 6.3 cups) in enough purified freshwater to make 3 litres total volume. This solution is added much less frequently than the other two parts. Each time you finish adding 3 litres of both parts of Recipe #2, add 240 mL (1 cup) of this stock solution. You can add it all at once or over time as you choose, depending on the aquarium's size and set up. Add it to a high flow area, preferably a sump. In a very small aquarium, or one without a sump, I suggest adding it slowly.

The first time it's added, I recommend adding just a small portion and making sure there isn't any problem (such as corals closing up due to stress) before adding the remainder. Make sure corals and other organisms don't get blasted with locally high concentrations of the main ingredients or impurities, or else they may become stressed. This solution contains about 37,250 ppm magnesium and 148,000 ppm sulfate.

Dosing Instructions

The dosing instructions are basically the same for each recipe, although any given aquarium will end up using about twice as much of recipe #2 as recipe #1 to add the same amount of calcium and alkalinity.
To initiate dosing, first adjust calcium and alkalinity to roughly their correct ranges. This may require a substantial dose of just the calcium part if calcium is low (e.g., below 380 ppm). I would suggest targeting calcium between 380 and 450 ppm, and alkalinity between 2.5 and 4 meq/L (7-11 dKH; 125-200 ppm calcium carbonate equivalents).

The Reef Chemistry Calculator can be found here.

This calculator shows how much of what parts to add in order to boost one or both of the parameters by a certain amount. This is a great calculator and can also be used for a number of the commercial products available.

Then, once things seem roughly correct, select a starting daily dose for routine dosing. Here are some suggested starting doses, but the exact values do not matter much. b

Table-1.jpg

Note: 1 gallon = 3.78 litres​

After a few days of dosing, note whether alkalinity is low, high or on target. Only bother to test alkalinity, not calcium, during this period, because it is much more sensitive than calcium to over- or underdosing. Adjust the dose up or down as necessary to increase or decrease the alkalinity. Once you have determined the proper dose, continue it until there is a substantial reason to adjust it (such as falling alkalinity as the corals increase in size). When adjusting the dose, raise or lower both of the recipe's parts together.

Resist the temptation to keep jiggering calcium and alkalinity independently. They will need occasional corrections, but that should not be the normal course of dosing unless there are substantial outside influences, such as water changes with a salt mix that does not match the tank's parameters or an error in making the mixes.

Check alkalinity fairly frequently to make sure the dosing continues at a suitable rate. Check it maybe once a week to once a month (or less as you get more experienced with the system and the tank). Check calcium once a month to once every few months to make sure it continues on track.

Remember to add an appropriate amount of Part 3 each time you finish adding 3 litres of Parts 1 and 2.

How you dose and how regularly is up to you, but you should add small amounts as often as possible to maintain stable water parameters.

A dosing pump is ideal for this scenario and I will provide details of my setup in another post.

Here are a couple of video's on the subject

 
Last edited:

Tang

Member
Jul 21, 2011
160
87
Sydney
Buy it all in bulk
Calc - Calcium Chloride Hexahydrate
Alk - Bicarb
Mag - Epsom Salts or Mag Chloride
 

firebird

Member
Aug 2, 2011
1,906
752
This is a really good post especially for newbies- when I first started I was told to just keep adding marine buffer to keep the ph up. It took me a while before I discovered the articles by Randy Holmes-Farley and realised I was doing it all wrong.
Is there any way to sticky this post MajicJ:cool:
 

MagicJ

Moderator
Jul 11, 2011
9,651
3,761
Hobart, Tasmania
This is a really good post especially for newbies- when I first started I was told to just keep adding marine buffer to keep the ph up. It took me a while before I discovered the articles by Randy Holmes-Farley and realised I was doing it all wrong.
Is there any way to sticky this post MajicJ:cool:
Thanks for your comments firebird - the post is already stickied :D. But we can do more than that - if you click on 'Post-it' at the bottom of your post you can add this, or any, post to your personal bookmarks which are accessed through the dropdown menu on your username in the top right.
 

Tang

Member
Jul 21, 2011
160
87
Sydney
Not a chance in hell. I do believe Reef Secrets will be selling them in 1kg bags soon though.
 

marineclass

Member
Jul 12, 2011
604
77
Gold Coast
Great info - do you think this is something that every tank should be adding? I only have a few corals and fish and my levels seem to be right for now however i do want to increase the corals soon. I dont see much point just yet but as I add more corals i should be dosing these right?
 

Tang

Member
Jul 21, 2011
160
87
Sydney
Pretty much, NSW changes should be enough in the interim to keep your parameters within suitable levels.

However, once you start adding more corals, demand increases.
 

MagicJ

Moderator
Jul 11, 2011
9,651
3,761
Hobart, Tasmania
Key point I should have mentioned - if you are not measuring it don't dose it !!

If you are testing for calcium/alkalinity/magnesium and they are falling below recommended levels which is not rectified via your normal water changes then you need to consider dosing.

These elements can be replenished via a number of means, including commercial products. kalk, calcium reactor etc - the choice is up to you. Randys Recipe is one option which is relatively cheap and does an acceptable job - hopefully it might also teach you something about what has been happening in your tank.
 

axela

Member
Aug 16, 2011
15
2
Melbourne, Victoria
Thank you so much for uploading those videos, i'm almost certain (90%) that i will go and get a dosing pump, calcium reactors are very pricey and do take up a lot of space.

Thanks again ;)
 

MagicJ

Moderator
Jul 11, 2011
9,651
3,761
Hobart, Tasmania
Thanks for your comments axela :). Now that the Chinese manufacturers are involved, dosing pumps have certainly become a more cost effective solution. I also think you can be more precise with the quantities dosed and they don't need constant adjustments which is a good thing.
 

Brenno

Member
Oct 11, 2011
7
0
Really good post... thanks for converting into the "Aussie version", although I have a few questions:

He says that the 3 solutions can all be mixed, but that part 3 is used "Each time you finish adding 3 litres of both parts of Recipe #2, add 240 mL (1 cup) of this stock solution"

- does he mean 3 litres of the combined part 1 + 2 solutions, or 3 litres of each part 1 and part 2?

- does this mean that if you were to combine all 3 solutions, you mix in the ratio, 1.5L part 1, 1.5L part 2, 0.24L part 3?

- when he quotes the guidline dosage rates, is it 0.2mL/gallon, 0.4mL/gallon, etc... does this mean 0.2mL of the combined solution as per the above ratio? Or does he mean 0.2mL/gallon of the combined part 1 and part 2, and then only add part 3 as decribed (1 cup after 3 litres of both part 1 and 2)?
 

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