[Sam the Slayer]

I was reading about sources for calcium and carbonates and I read about dolomite camg(co3)2. I read that when put in solution and a mild acid is applied this separates the ca, mg and carbon from each other and that got me thinking. Are people in our hobby using dolomite as a base or additive in their substrate with the intention of nitrification creating an acidic environment which would in turn release the bond of ca, mg and co2?

I remember a humorous poster talking about dolomite being able to grow certain plants crazy quick a while back and I am wondering “was he to a certain extent right?”

I know dolomite has been used as a base for a long time as a calcium source but are people out there using it intentionally as a substrate carbon source as well?

Anyone with deep experience or chemists who can actually grow plants (lol) know more about this?


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[ElleDee]

This would result in additional carbonate (co3), not co2. I think there's a bit in Walstad's book about some plants being able to use carbonate as a carbon source if they have to, but most plants can't do this and even the ones that do prefer not to. If your plants can't use it, it just increases your kh.

 

[AVN]

It's been experimented with.

Some key things to note are that some dolomite+compost mixtures are manufactured using some kind of resin, which reconstitutes in water and stratifies in the water column. It is extremely messy, almost akin to a dirted tank, and it forms a light mud-like sediment. The dirt, wood, and decaying organics will also tank your pH and spike your nitrates

Powdered dolomite might work as an additive, but I'm not versed on its usage.

 

[Deanna]

Dolomite is virtually insoluble in water, unless pH is acidic. However, the Dolomite is constantly trying to drive the pH up so that it doesn't have to dissolve anymore. Unless your BB are chewing up a lot of TAN (total ammonia), nitrification isn't likely to cause enough acidity to make a difference.

ElleDee answered your question about CO2 (there is none generated of any consequence) and there are much easier ways to provide Ca, Mg and carbonates.

Perhaps we can help better if you can relate your objective.

 

[jeffkrol]

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[Sam the Slayer]

So I am no scientist and am maybe not reading these articles, and a couple of others, correctly but it looks like if you expose co3 to a mild acid it separates the carbonate into a bicarbonate and then into straight co2 and hydrogen. I look up “mild acid” as an acid with a ph from 5-just under 7.

I also read someone on here talking about their substrate ph and they were stating it was low although I don’t remember specifically.

It seems like with our co2 injected tanks or even our low tech tanks you would likely have an acidic substrate even though the tank water will be higher.

I stumbled on this thought when trying to find the right carbonate for a kh/gh+ liquid remineralizer and it’s making sense to me... even though it may be wrong lol.

Carbonate chemistry

Calcium carbonate is the principal mineral component of limestone. Its chemical and physical properties lie behind the modern-day uses of limestone as well as the unique limestone landscapes of the countryside.

www.sciencelearn.org.nz

Calcium carbonate - Wikipedia

en.wikipedia.org

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[Tiger15]

I use dolomite gravel as substrate for all my tanks to buffer up PH and gH so I never have to dose Ca and and Mg. It is not a carbon source, just carbonate of Ca and Mg and is only slightly soluble unless your water is very acidic.

 

[ElleDee]

@Tiger15, how much of an effect on pH, GH and KH do you see as a result of the substrate? How're the readings in your tank compared to your water source?

 

[Sam the Slayer]

Perhaps we can help better if you can relate your objective.

My objective is honestly just to explore a thought.

When looking at Tom Barr’s tank where he used a full substrate of it there is no way you could accomplish what I’m referring to as there is no way to create an acidic enough environment using that as a substrate but let’s say you used an aquas oil or even an inert substrate and applied nitrification or co2 injection and added maybe several grams at the base and then just used it like root tabs that this could aid in a more carbon rich~/nutrient rich~ environment in the substrate.

Again this is just a thought I’m exploring from a few hours ago lol. Just seems like there could be a path to usefulness but not that that would be any better than many other ways of achieving ones plant growth goals. I’ve never done it and grown all kinds of fun stuff.


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[Savetheplants]

I'm running a similar experiment trying to dissolve CaCO3. It won't dissolve. I tried dissolving it with CO2. That didn't work. They say you can dissolve 47 mg/l. That's not true. They say you can dissolve 15 mg/l at 25 Celcius. That's also not true. And people ask me why STP why? My idea is to slowly dissolve a little CaCO3 in one form or another to keep my GH and KH up all week so I can dose less bicarbonate and reduce TDS. I'm not going for the African Cichlid hard water tank. Maybe your idea will work but it sounds like you're going to alter your substrate to find out. That's kind of hairy.

 

[Sam the Slayer]

I'm running a similar experiment trying to dissolve CaCO3. It won't dissolve. I tried dissolving it with CO2. That didn't work. They say you can dissolve 47 mg/l. That's not true. They say you can dissolve 15 mg/l at 25 Celcius. That's also not true. And people ask me why STP why? My idea is to slowly dissolve a little CaCO3 in one form or another to keep my GH and KH up all week so I can dose less bicarbonate and reduce TDS. I'm not going for the African Cichlid hard water tank. Maybe your idea will work but it sounds like you're going to alter your substrate to find out. That's kind of hairy.

Yes I saw that they say you can get 47ppm in there which seems like a lot to dissolve. I’ve used caco3 as a part of my remineralizer in inert substrates and it dissolves fully in about 12 hours for me but I only target 10 ppm with it and use caso4 for the rest. My ph is about 5.8 with co2 on. I’ve created a solution with it and it’s not dissolved at all but surprisingly works pretty spot on when I shake the bottle before use.

I think the 47ppm is when you go hot with it. I think really hot.

How are you using the co2 with it? I’m picturing a co2 reactor of sorts.


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[Savetheplants]

I dropped a limewood diffuser in a bottle and turned up the CO2 trying to dissolve some brewer's Calcium Carbonate. That was years ago. I tried last week without CO2 using a powerhead to mix 15 mg/l of it for a couple of days without success. I think there is already a little bit of it left dissolved in my store bought RO water. That would probably keep any more of it from dissolving. I bought a good Calcium, Magnesium, Total Hardness test kit to try to figure things out this weekend. Interestingly, CaCO3 dissolves better at lower temperatures. Counterintuitive isn't it?

 

[Sam the Slayer]

I dropped a limewood diffuser in a bottle and turned up the CO2 trying to dissolve some brewer's Calcium Carbonate. That was years ago. I tried last week without CO2 using a powerhead to mix 15 mg/l of it for a couple of days without success. I think there is already a little bit of it left dissolved in my store bought RO water. I bought a good Calcium, Magnesium, Total Hardness test kit to try to figure things out this weekend. That would probably keep any more of it from dissolving. Interestingly, CaCO3 dissolves better at lower temperatures. Counterintuitive isn't it?

So funny enough with the low temperatures; I have my remineralizer mix in the fridge now to see if it does dissolve better... it hasn’t yet lol. My concentrations are high though. Enough to where 2ml/gallon = 6gh/kh

I wonder if humic acid could work? I have some saved from catalpa leaves. I’ll have to look it up.


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[Savetheplants]

Don't even get me started on my peat moss trials. What a mess. Those old aquarium books from the Sixties sent me down a few rabbit holes. I thought about using ice to cool the water. There are acids but that's too water chemistry altering and you just get back to where you started only maybe with a little less Sulfate, Chloride and Sodium if it works. Besides I already have too many chemicals. It is a strange hobby when it comes to all the chemicals. People watching me work on the tank don't understand.

 

[Sam the Slayer]

Oh I get it! Unless you’re in it...

I want to clarify what I’m wondering about with this question. Would starting out with a couple of grams per 20 gallon footprint and then adding some more over time via capsules like root tabs have a beneficial effect on getting a little more carbon to the roots of the plants? Doing this would only add 1.61kh to the tank plus whatever crossovers there are from the capsules. The ca/mg are not really in my thoughts when I’m thinking of this but this whole process is naturally occurring so maybe it would help a little here as well.

I’ll eventually have to setup a proper experiment to see what differences there are if any.


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[Savetheplants]

Would starting out with a couple of grams per 20 gallon footprint and then adding some more over time via capsules like root tabs have a beneficial effect on getting a little more carbon to the roots of the plants?

I don't think so based on what ElleDee, Deanna and Tiger15 posted. Don't plants exchange gasses through their leaves and other nutrients through their roots? It's the acidity caused by CO2 in our tanks that's stripping the CO3 from the dolimite. You would be using a lot CO2 to try to get a little CO2. This is not the alchemists' long sought-after recipe for turning lead into gold or a perpetual motion machine. You would effectively be putting more energy into the system than you would be getting out of it.

 

[Sam the Slayer]

I don't think so based on what ElleDee, Deanna and Tiger15 posted. Don't plants exchange gasses through their leaves and other nutrients through their roots? It's the acidity caused by CO2 in our tanks that's stripping the CO3 from the dolimite. You would be using a lot CO2 to try to get a little CO2. This is not the alchemists' long saught-after recipe for turning lead into gold or a perpetual motion machine. You would effectively be putting more energy into the system than you would be getting out of it.

I am more thinking of an acidic environment in general in the substrate regardless of co2 injection say via the ammonia cycle. In terms of which part of the plant takes up what, I’m not 100%. I assume they have adapted to take what they can get and make the best of it. I think I’ll test this thought in two identical low tech setups. I’m setting up new shrimp tanks soon so I could test it there just to see if it provides an edge of any kind. Based on continued reading I am convinced that the chemistry of it is sound; provide carbonates with an acid and it will degrade and release the carbon. How good is this? I assume minimal if anything but hey, if it helps a little bit, it’s a very cheap thing to do.


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[Tiger15]

@Tiger15, how much of an effect on pH, GH and KH do you see as a result of the substrate? How're the readings in your tank compared to your water source?

Dolomite is CaMg(CO3)2 and will raise pH, gH and kH, but only slightly. Dolomite is slightly less soluble than calcite CaCO3, and order of magnitude less soluble than baking soda Na2CO3.

In my CO2 tank with high bioload and weekly 75% water change, the pre injection pH is around 7.4, kH 4 and gH 8.

In my non CO2 tank with infrequent WC, pH tops at 7.8. Water comes out of my tap has pH 7.6.

 

[Deanna]

Attempting to consolidate a response to many of the above posts:

If you are simply trying to raise KH, I prefer KHCO3 to NaHCO3 (baking soda). That way, you are adding potassium (a macro) rather than sodium (may build to harmful levels). For my KH purposes, I usually add either CaCO3 and/or MgCO3, only occasionally supplementing with KHCO3. Because I use RO water, I have to be careful to get enough sulfate which, in my dosing, only comes from K2SO4, MgSO4 or CaSO4. I try to maintain pH 6.0 to maximize the sweet spot for nutrient uptake and KHCO3 gives me too much K, if used alone, to give me enough KH to reach the pH 6.0. So, I use CACO3 (since I would have to dry dose CaSO4 anyway) and bridge any dKH deficit (caused by balancing the Ca contribution from CaCO3) with MgCO3.

In our typical temperature ranges, CaCO3 and MgCO3 will dissolve (much better than Dolomite), but as a function of pH. In my case, with pH of 6 or less (pH <5 if not buffered), the solubility limits of CaCO3 are about 80mg/gal and, for MgCO3, about 70mg/gal, but they do take up to a day to fully dissolve at these maximum points. I generally don’t need the maximum. Dosing both at the maximum would give you about 24ppm carbonates, but about 8ppm Ca and about 5ppm Mg as well.

Plants do take-up nutrients through their leaves, in addition to their roots. This is why you can fully develop any plant by dosing the water column only and using inert substrate (which is what I do). Some of the nutrients, over time, do enter the substrate, with some making various new combinations, where the roots will also consume them. This includes CO2 but, again, the leaves are perfectly capable of getting all the carbon that the plant needs.

 

[Sam the Slayer]

Do you all know how measure the ph of the substrate? Would you do it like you would soil? Or long syringe and just pull water from the bottom (this seems wrong)?


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