[niko]

Some people in the thread below and in PMs asked about how to use Dolomite as a source of Ca and Mg.
http://www.plantedtank.net/forums/1...lizers-pictures-extremely-healthy-plants.html

First off - the use of Dolomite is not something you should consider to be a "magic wand" to solve problems. There isn't a single such factor in a planted tank. They all work together, as simple as that. The real challenge is to find out HOW everything works together inside the glass box, not on paper/screen. So far, 15 years into the US internet hobby, we can't say we have made great progress in answering that question.

Lately, there has been more and more interest in keeping the fertilization of a planted tank to a minimum while still being able to grow healthy plants. The fact that the Japanese company ADA has been doing that forever is another topic. The use of Dolomite is exactly along the lines of adding the least needed - it does not add Chloride, Sulphur, Potassium, or extra microelements as practically all popular water column fertilizers do.

So using Dolomite is a way to avoid accumulation of unneeded substances. Some people have started to suspect that accumulation of nitrients (especially micros) is a much greater problem than we all think. Big regular water changes do not solve that problem despite calculations that show they will. At the end - the use of "clean" sources of nutrients, that do not add additional elements is a better practice overall.

There is also a German line of fertilizers that includes products supplied in forms that have proven to be more effective (Aqua Rebel). Dolomite too has an interesting effect on plants that is beyond just supplying Ca and Mg. Dolomite solubilizes gradually and this process maybe what makes it different and more effective. Meaning that Mg from Epsom Salt (MgSO4) for example will supply Mg but the way this Mg is supplied appears to be inferior to using Dolomite. Not to mention the addition of S, which is an example of an unneeded element added along with the Mg and never tested for.

Ok. So if you have decided to give Dolomite a try here's what you need to know:

1. I use Dolomite powder made by KAL.

Someone asked why I use powder and not Dolomite pebbles which will dissolve even slower. You can find Dolomite gravel by road construction sites - it is used as a base under concrete and asphalt. But powder is way easier to measure. Dolomite does not dissolve immediately in water but it does dissolve pretty quickly. A 1" rock will be an overkill in a 100 gallon tank. Below you will see actual calculations and will agree that powder is the way to go.

2. Dolomite will supply more Ca than Mg.
That is an important detail. Using Dolomite or not your goal should be to maintain a Ca:Mg ratio of 3-4:1. Adjusting your actual ratio to that 4:1 ratio can not be done with Dolomite alone. That will be described in details below.

3. To adjust the Ca:Mg ratio in a "clean" way, not adding anything extra that will accumulate in the tank we use:
- To raise Ca - Dolomite (aslo raises Mg but less than Ca)
- To raise Mg - MgCO3.

4. Both Dolomite and MgCO3 increase GH and KH.
This certainly appears like a big problem but it isn't. Once the Ca:Mg ratio is adjusted so little Dolomite is used that the GH and KH are easily adjusted to whatever value you want them to be. As we all know ideally a planted tank should have KH of 2-4 and GH of no more than 5.

So: We use MgCO3 to add Mg and Dolomite to add Ca until we adjust the Ca:Mg ratio to 3-4:1 This is done gradually. Do not add enough Dolomite to adjust your Ca:Mg ratio in big steps. Everything in a planted tank must be done gradually and Dolomite and MgCO3 are no exception. It will take weeks to adjust the Ca:Mg ratio in a tank that has a GH of 10 and 100 ppm Ca. Keep that in mind, it's important.
Once we have the Ca:Mg right and the KH and GH more or less in line we add mainly Dolomite (+very little if any MgCO3 if needed). Fine tuning KH and GH is done, once again, with small and frequent water changes (every 3 days, 10-15%).

Calculations:

I use the calculators on the German website FlowGrow.de

Theoretical tank:
******************
Go to the link below:
Ca:Mg Berechnung - Flowgrow Datenbank

Make sure that the radio button "Magnesium bestimmen" is selected.

First we will enter numbers that give us a good Ca:Mg ratio:
-----------------------------------------------------
Enter GH=7 and Ca=34. They result in a good Ca:Mg ratio.
Enter 7 for "Gesamthärte (GH)".
Enter 34 for "Referenzwert"

Click the green button "Berechnen".
The result is displayed in a white box to the right: We have 9.76 mg/L Mg (mg/L is equal to ppm). And the Ca:Mg ratio is 3.48:1.
Perfect.

Real tank:
******************
Your real Ca:Mg ratio is off:
-----------------------------------------------------

In this example the water test showed GH=4 and Ca=34 ppm. From example of the perfect tank above you can already tell that 34 ppm of Ca should be paired with GH=7 to have a good Ca:Mg ratio. In other words the Ca is too much for the GH of 4.

Enter 4 for "Gesamthärte (GH)".
Enter 34 for "Referenzwert".

Click the green button "Berechnen".
The result is displayed in a white box to the right: You have -3.31mg/L Mg. And the Ca:Mg ratio is negative also. This means that the Ca is way too much. So you need to increase the Mg.

Increasing the Mg:
*********************

-->How much Mg do we need to add to get to the good ratio of 4:1 Ca:Mg?
Look at the amount of Mg: it is -3.31. You want it to be 9.76 (like in the "Good" Ca:Mg ratio" example. So you need to add enough MgCO3 to increase the Mg to 9.76. Note - we are adding MgCO3. Not Dolomite!
You are starting from -3.31 and you need to get to 9.76. So you need to add about -3.31 + 9.76 = 13 ppm Mg.
We will use a 65 gallon tank as an example.

How much MgCO3 we need to add to a 65 gallon tank so we add 13 ppm of Mg?
***************************************************************************
Go to this page:
Dosierberechnung - Flowgrow Datenbank

65 gallons is roughly 200 liters. Enter 200 in the "Beckenvolumen" box. This is approximate but will work. From what I have seen 200 is a good approximation.

Ignore the "Zugabeintervall" box below "Beckenvolumen".

Under "Nahrstoff" find the drop box "Magnesium (Mg)". Leave it as it is.
In the drop box to the right of ""Magnesium (Mg)" choose "Magnesiumcarbonat MgCO3".

Enter 10 in the box that has a "g" on the right. The "g" is for "grams".

Click the green button "Berechnen" (not "Loshen" which deletes this row of drop downs).

The results are shown in a table under the green button "Berechnen in a table named "Ergebnis". The table now shows how much of what element you added with your 10 grams of MgCO3. In this case it is 14.41 mg/L (=ppm).

Now scroll below that table and look at the two white boxes below. They show how the KH and GH are affected by the addition of 10 g. of MgCO3. In this case KH was raised by 3.32 and also GH was raised by 3.32.
That means that we adjusted the GH to 7 (like the "Good" tank in the beginning of our example) and the Ca:Mg ratio should be good. But your starting KH of 4 may now read 7. That is not high but it is something to expect when we test next week. From my experience, on my tanks, the KH will actually jump only to about 6 max.

Note that other than Mg there are no extra chemical elements added. But if you use the usual source of Mg - Epsom Salt - and select it as"MgSO4.7H2O Bittersalz" you will see that it adds Mg and Sulfur. There is no need for the Sulfur. Or is there? Nobody can really tell you. If you add Epsom Salt to your tank to raise the Mg you are also constantly building the S. And never testing for it. Toxicity may happen and you don't realize why.

If you followed the above steps you should now know how to adjust your Ca:Mg ratio using MgCO3. But this thread was about Dolomite.

As you understand - if we try to adjust the Ca:Mg ratio adding Dolomite we will end up with raising the Ca, but also the GH and the Mg. We can use another source of Ca - like CaCl2 - but in this case we will be adding Chloride to the tank. Not the best idea if we strive for the least accumulation of anything. So the calculations say that by adding Dolomite we will be increasing the Mg and never get away from adding more Ca than Mg. That is why we use MgCO3 first to get the Ca:Mg ratio right with a "clean" source of Mg. Then we use Dolomite to maintain that ratio. Once again - think of the Dolomite as a source of Ca+Mg and the MgCO3 as a source of Mg.

To reiterate - this thread is about using alternative, clean, sources of the nutrients that the plants need AND about supplying them in a form that has proven to be very efficient. This thread is not about right vs. wrong.

An experience from real life: For one of my tanks adding the calculated dose of Dolomite ended up in a good Ca:Mg ratio in about 4-5 days because the plants where consuming the Mg very fast. That is not that strange - after all Mg is part of the Chlorophyll molecule. But the rate of consumption of Mg in that particular tank was extremely fast. After about 10 days the plants were growing very strong and very fast but the consumption of Mg slowed down considerably. That doesn't make much sense but apparently the plants were ramping up for great growth and needed extra Mg before the home run and less Mg during fast growth.

That example shows that the calculations would not predict what the Ca:Mg ratio would be after 4-5 days because the plants maybe in a state that requires more or less Mg. It goes without saying that the same applies for any other nutrient. Frequent testing and careful fertilization maybe an obvious solution. But it is many times better to setup the tank in such a way that fluctuations are not excessive.


Test kit:
For testing GH, KH, Ca, and calculating Mg precisely I use an $100 test kit made by Hach. Cheap test kits sold in fish stores will throw you off. If you tried the calculations above with different values you will see how hard it is to get the Ca:Mg ratio right. Small changes in Gh or Ca change the ratio too much. Play with the values of GH and/or Ca in the calculator below. Look how the Ca:Mg ratio changes in the white box to the right ("Ca:Mg Verhaltnis"). It's pretty tricky to get it between 3-4:1.
Ca:Mg Berechnung - Flowgrow Datenbank

So a good test kit is a must.
Hardness (Total & Calcium) Test Kit, Model HA-4P MG-L | Hach USA - Overview | Hach

 

[PlantedRich]

I guess it is really a basic question but is there something that leads you believe there is not plenty of calcium in the Dallas water? I usually find that when water is drawn from a limestone aquifer, there are plenty of hard water minerals. Many of the folks in the Austin area use water softeners for house use just because there is so much calcium and magnesium.
Not knowing where your source may be leaves me wondering what caused the worry.

 

[niko]

I guess it is really a basic question but is there something that leads you believe there is not plenty of calcium in the Dallas water? I usually find that when water is drawn from a limestone aquifer, there are plenty of hard water minerals. Many of the folks in the Austin area use water softeners for house use just because there is so much calcium and magnesium.
Not knowing where your source may be leaves me wondering what caused the worry.

I didn't look at the tap water and then decide what to do about Calcium and Magnesium. Here's how it went:

The first time around, on 2002, I didn't consider the water. I saw a gravel which appearance I liked, put it in the tank, and had my first experience with Dolomite dissolving in water and plants growing like on steroids. Then for 10 years never used it in any way.

The second time around I had a tank in which the GH had climbed to 18. I had been using "EI" in the sense most people understand it - add a bunch of fertilizers and change a lot of water every week. Everything is supposed to never accumulate. Yes, things accumulate, and this is what some people are starting to figure out and work on lately. In my case the GH had climbed so high because of my stupidity - I never suspected that a tank chock full of plants would not absorb my pinch of CaCl2 once a week considering I was using 100% RO for water changes. Plants looked fine but not really growing their best - customer tank so if anything was ugly I'd have to change it.

The steps described in the first post in this thread are taken from the experience with that tank. I had to bring the GH down AND adjust the Ca:Mg. But going from GH18 to GH3 with CaCl2 and MgSO4 would be a disaster - adding tons of Cl2 and S. So I used sources tha didn't add them. It is all described above.

How do I know if the Dolomite really made a difference? Well, at first I tried to reduce GH and adjust Ca:Mg with CaCl2 and MgSO4. Plants just would not budge growing. I started to suspect accumulation of "something" - most likely S. So I started to use MgCO3 instead of MgSO4. That lead me to looking for a "clean" source of Mg - one without S. I remembered the Dolomite experience from 10 years ago and gave Dolomite a try. The tank transformed. It had never looked better for many years. Plants grew, some plants that I had not seen in years came back from nowhere.

Was that huge change due to lowering GH only? Or because Dolomite does something a little different? Not sure. So here it is:

Third time around, 180 gallon tank. Water changes with 100% RO. Adjusted the GH of 8 to 3. Adjusted the Ca:Mg from about 8:1 to 3:1using only Dolomite and MgCO3, never bothered with CaCl2 and MgSO4. Omg. Same thing - plants exploded. I posted about that in the other thread already. I reduced my DIY LED fixture from 180W to only 25W and the growth slowed but I still get shocking rates at a depth of 24" and only 25W. No other fertilizers, just 1" of AquaSoil with 6 months old root tabs. What I see makes a difference is the CO2 - that tank has been without CO2 now for 8 days. Everything looks absolutely perfect, but the plants grow way slower.

That last one is a story that doesn't make a lot of sense. Be my guest and use 25W of any light over a 2' tall, 6' long tank + add a little CO2, maybe to 6.8. You are not getting anywhere fast. But this tank is. That makes me look for explanations in the microorganism setup of the tank, Dolomite dissolving in some efficient to use way, etc.

Only way you can know if Dolomite works for you is to give it an honest try. I suggest using good test kits - one of the reasons I had GH18 in the first tank I described were bad test kits.

 

[easternlethal]

To reiterate - this thread is about using alternative, clean, sources of the nutrients that the plants need AND about supplying them in a form that has proven to be very efficient. This thread is not about right vs. wrong.

Can you elaborate a bit more on what you mean by 'clean'? How is Mg in dolomite' cleaner' than Mg in MgSO4?

Or do you mean 'pure' because dolomite does not include SO4? If so I think we'd need to know why SO4 is bad since I understand it has benefits for plants too.

Or do you mean it's better simply because it's naturally occurring and in that sense Epsom salts would work too?

I think maybe you prefer it because it's pure since I read your post that you are trying to prevent 'accumulation'. But what is so bad about that, given it is also a natural phenomenon? Do you suppose that an EI tank has 'accumulated' more than a natural lake?

 

[Hoppy]

I continue to read the posts on this general subject. My hope is that I will eventually learn something that is helpful to me. Until then I have no idea whether I'm wasting my time (which isn't worth all that much anyway) or if I'm on a path that will lead me somewhere. So, please continue.....

 

[Solcielo lawrencia]

Excess sulfate can interfere with phosphate uptake. According to one crop nutrition expert, the ideal P:S is 1:1. How much sulfur is added with the addition of calcium sulfate, magnesium sulfate, and potassium sulfate?

Ca=15, S=12
Mg=5, S=6.6
K=7.5, S=3
PO4=2.6, P=0.8

P:S= 0.8:21.6 = 1:27

To achieve a 1:1 would require adding more than 21mg/L of P, which is 66mg/L (ppm) of phosphate. Is anyone going to add that much phosphate to achieve a P:S of 1:1?

So if there is an explanation as to why using dolomite improved growth, then it may very well be as niko stated, that it prevents the addition of unnecessary sulfate.

 

[niko]

I said it many times above:

1. Calculations, water changes, concentrations mean nothing when your tank is not doing well.

You did everything "right". You followed EI, PPS, ADA, whatever. Plants aren't growing anyway. What is wrong? Many things you don't know about.

One reason could be accumulation. Of something. Could be some minor trace element. Could be S or K or P. Whatever. Change water as much as you can. Do you think you removed all accumulated crap? You have no clue.

Ok. So it makes sense to NOT ADD things if you can avoid adding them. For example we do not want extra S or K or Cl.

Choose:
CaMg-Carbonate (Dolomite) for Mg instead of MgSO4 which adds S.
CaMg-Carbonate (Dolomite) for Ca instead of CaCl2 which adds Cl.
Calcium Nitrate for Ca instead of CaCl2 which adds Cl.
Calcium Nitrate for N instead of KNO3 which adds K.
Magnesium Nitrate for Mg instead of MgSO4 which adds S.
Magnesium Nitrate for N instead of KNO3 which adds K.

You get the idea: Dolomite adds Ca, Mg, and Carbonate. Nothing else. You can call it a "clean" source of Ca ang Mg because it does not add anything that secretly accumulates. The Carbonate will show as water hardness and that is easily adjusted through water changes and a very simple test.

2.The SECOND reason I talk about Dolomite is that when it dissolves in the aquarium it is definitely more efficient than adding CaCl2 and MgSO4. The plants respond in a visibly faster and better way. Write a scientific article explaining or denying that - the plants will grow better anyway.

Do you have to use Dolomite? It's up to you.

Bump:

... Do you suppose that an EI tank has 'accumulated' more than a natural lake?

Fertilize your tank according to EI. Take a water sample to your water company. They will ask you where did you get that toxic water. It has so much Nitrate and Phosphate that it will be classified as toxic. And it has lots of other fertilizers too - all in concentrations that are very very high. You can not find any natural body of water with such levels of nutrients. But somehow all the plants we grow in our tanks survive in Nature.

If you follow EI you will be changing a lot of water. To avoid accumulation of fertilizers. Good luck. The nice calculation shows that if you change 50% of the water once a week + your plants eat X amount of fertilizers you will always remove all remaining ferts with the water change. That is not so. Some things will gradually accumulate. A nice calculation and graph is not real life.

So it is better to keep things out of the tank. Not to try to take them out once you put them in.

 

[niko]

I continue to read the posts on this general subject. My hope is that I will eventually learn something that is helpful to me. Until then I have no idea whether I'm wasting my time (which isn't worth all that much anyway) or if I'm on a path that will lead me somewhere. So, please continue.....

Get some $4 Dolomite. Follow whatever calculations make sense. Get the Ca:Mg ratio to be 3-4:1. See if your plants are doing better. What do you have to lose?

If I show you growth rate pictures will you be convinced? Or you will tell me that there are a million other explanations why when I added Dolomite my plants started to grow that way? And all along you will assume that I'm telling you the entire truth? This last bit is way more widespread than we think. Beautiful aquascapes we all know have such embarrassing secrets that nobody will even believe the truth.

So, bottom line - spend $4. Try. See for yourself.

Bump:

Excess sulfate can interfere with phosphate uptake. According to one crop nutrition expert, the ideal P:S is 1:1. How much sulfur is added with the addition of calcium sulfate, magnesium sulfate, and potassium sulfate?

Ca=15, S=12
Mg=5, S=6.6
K=7.5, S=3
PO4=2.6, P=0.8

P:S= 0.8:21.6 = 1:27

To achieve a 1:1 would require adding more than 21mg/L of P, which is 66mg/L (ppm) of phosphate. Is anyone going to add that much phosphate to achieve a P:S of 1:1?

So if there is an explanation as to why using dolomite improved growth, then it may very well be as niko stated, that it prevents the addition of unnecessary sulfate.

Maybe you can also find some information on how Dolomite dissolves in water and how that can be beneficial to the aquatic plants. I do not know of such an article. But as I said - when I started using Dolomite the plants responded very, very fast. I do not attribute that to S not being accumulated. It certainly seems like a result of the transitional states of the ions.

Get some Dolomite. Put in in a tank with CO2. See the results. You will start to wonder what really is going on.

 

[Solcielo lawrencia]

To test if of the reason is due to carbonates, prior to adding dolomite, dissolve it in vinegar to reduce carbonate into carbon dioxide that will be released into the atmosphere. This would eliminate the effects of carbonate reducing to co2 while in the aquarium. IOW, it eliminates CO2 as the variable as dolomite dissolves as the reason for the improved plant growth.

 

[brwaldbaum]

To test if of the reason is due to carbonates, prior to adding dolomite, dissolve it in vinegar to reduce carbonate into carbon dioxide that will be released into the atmosphere. This would eliminate the effects of carbonate reducing to co2 while in the aquarium. IOW, it eliminates CO2 as the variable as dolomite dissolves as the reason for the improved plant growth.

How do you control for the acetate?

 

[bluesand]

Hey niko, is there another way of testing your method without buying those expensive test kit? can i use RO water and add Dolomite alone?

 

[easternlethal]

Excess sulfate can interfere with phosphate uptake.

What is your source for this and how much -> 'excess'? And how are sulphates worse than carbonates?

I can find articles that say sulphate reduction plays an important role too.

 

[dzega]

snake oil spotted. All the Ca an Mg in tap water comes from dolomite so you are not adding anything that is not already there.

 

[Clinton Parsons]

I have almost NO gh out of my well. TDS 40, 0kh, 0 GH. I have just been adding baking soda and GLA GH Booster (1 gram and 3.5 grams (maybe 3) per 5 gallons water change IIRC)

So if you wanted to add dolomite to an established tank, how much dolomite would you inject under the aquasoil per unit area sq? I just ordered four ounces of the stuff. It can't hurt anything.

BRWaldBaum, plants and bacteria can use the acetate via the glyoxylate cycle as a source of carbon, so you bring up a great point.

ADA used to sell Penac P. I think it was just powdered calcium carbonate. I think their contract expired recently and they discontinued it, though.

 

[GrampsGrunge]

snake oil spotted. All the Ca an Mg in tap water comes from dolomite so you are not adding anything that is not already there.

Unless of course you line in an area that's largely Limestone (CaO3), or in our case were you have virtually no carbonate hardness at all..

 

[Seattle_Aquarist]

Unless of course you line in an area that's largely Limestone (CaO3), or in our case were you have virtually no carbonate hardness at all..

Hi GrampsGrunge,

I am guessing you meant that there would be minimum Magnesium (Mg) in the water? Limestone (aka calcium carbonate) would have a lot of carbonate in the water.

 

[PortalMasteryRy]

I ordered the powder on Amazon to try this out. I am the lucky few who can monitor my Ca,Mg and SO4 levels using a photometer and I'm interested to see how my plants will grow with less sulfate being added. The only reason I back down on dosing Ca and K was because of adding too much sulfate in the water by using K2SO4 and CaSO4.

Regarding Ca:Mg levels. I've seen good results keeping Mg levels around 15-20 ppm with Ca around 40-60 ppm.

 

[GrampsGrunge]

Hi GrampsGrunge,

I am guessing you meant that there would be minimum Magnesium (Mg) in the water? Limestone (aka calcium carbonate) would have a lot of carbonate in the water.

Well yes, like in Southern England with the chalky soils, it would seem that magnesium would be fairly scant in chalk based soils or ground-water.

Our local case, is entirely different as we have no hardness at all, either carbonate of general.

 

[Clinton Parsons]

Powder arrived today. How much to add per unit area of substrate?

Not looking to micromanage my gh/kh, just want to add some to buffer (pun intended) any nutrient deficiencies in ca, mg that may or may not ever arise.

 

[Seattle_Aquarist]

Hi Clinton,

I have been dosing dolomite for a little over two weeks as a substitute for the Equilibrium, CaCl2, and MgSO4 I was using in hopes of correcting an issue I have been having with one tank. I started a thread and made the first post this weekend.

Clinton, do you normally dose Equilibrium, Mg, or Ca? If not, then initially I would dose 1/8 teaspoon per 10 gallons which will give you about 4ppm of Ca and 2ppm of Mg. If you do a water change, use the same 1/8 teaspoon per 10 gallons of water changed. That should increase your buffering and provide extra Ca and Mg.