# Ok - so can we stick a fork in this one? Dosing CA/MG



## pbohart (Feb 16, 2005)

Ok - so can we stick a fork in this one: No more CA/MG dosing needed?

I know you guys hate over-generalized "rules of thumb" - but I am sensing strong and building momentum behind the idea that we no longer need to buffer our water with MG/CA - desipte how low our GH/KH is out of the tap.

The lower the KH, the better? Heck - grow plants in 0 KH...a discus tank for all?!? 

In all seriousness, I have KH=0 out of the tap. I have been buffering with MG and CaCo3 for years. My goal was to prevent curly leaves. Now I have solved all of my curly leaf problems by cutting my light WAY down (cycling my 3.5WG of 4x65 CFs) and keeping the CO2 very high.

So....can I stop adding the CA and MG? I could save some money....and avoid the 24 hours of cloudy water that follows a CA dosing. That would be nice.

If this is an overgeneralization, then help me out - when *does* one need to dose CA and MG?

Love it!

Patrick


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## Glouglou (Feb 21, 2006)

*Stop dosing Ca & Mg*

Well if it work for you, good, go ahead. Personally, I think that Ca and Mg are essential and by deduction if you keep adding water with no KH and no Mg, the plants will used the remaining Ca and Mg and will become deficient sometimes.


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## Edward (May 25, 2004)

You know KH has nothing to do with Ca and Mg?


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## BryceM (Nov 6, 2005)

I second what Edward is saying. Let's be clear here. GH is a measure of divalent cations, most importantly Ca and Mg. KH is a measure of buffering capacity, most importantly carbonate, and to a lesser extent, phosphate. Other than coincidentally ocurring in nature, the two are not at all related. Very few plants show a requirement for high KH. Many do slightly better toward the lower end of the KH spectrum. Most don't care that much.

The Ca & Mg "issue" certainly isn't "dead". If anything, we've just scratched the surface in understanding uptake, utilization, dosing, and interactions of these elements.

I suspect that the sucess of tanks with low levels of GH probably has something to do with the composition of the substrate. Tanks with high substrate levels of CaCO3 or other calcium & Magnesium salts probably tolerate no extra suplementation better.

Calcium uptake by plants is also much more complicated than we'd like it to be. Just because it's in the water doesn't mean the plants can get to it. Uptake can apparently be affected by the concentrations of other cations, especially magnesium, maybe iron, and probably a few others.

There is no question about the fact that plants do need Ca & Mg, from some source. A large proportion of their dry weight comes from these elements.

BTW, you can avoid clouding issues when dosing calcium by changing to CaCl2 or CaSO4. Both Barr Booster and Seachem's Equilibrium use CaSO4. You can supply carbonate (if desired) by using NaHCO3.


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## ed seeley (Dec 1, 2006)

*Perhaps not strictly on subject...*

Really not sure if this is the place for this but think it is loosely connected.

I currently use RO water for my planted tank and currently re-mineralise with small amounts of RO right powder, which now seems to be unobtainable here in the UK. I can however get powdered fertilisers from Aqua Essentials and they do a large range of compunds.

The crux is can i use MgSO4 and CaSO4 (and a dose of trace minerals) to do the same job as the powdered RO Right? Would CaCO3 be needed? Or could/should I add KCO3 as well to provide potassium and carbonates?

Any ideas anyone?


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## BryceM (Nov 6, 2005)

CaSO4 & MgSO4 are great choices for reconstituting RO. Use them to supply the Ca & Mg. If you desire a certain KH, you can get there by adding either NaHCO3 or K2CO3. You can use CaCO3 if you'd like, but it dissolves slowly, clouds the water, and raises both GH and KH.


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## ed seeley (Dec 1, 2006)

Thanks,
any ideas on the kinds of quantities and ratios needed for a good mix? My supplier over here suggests a 1:3 mix (MgSo4:CaSo4). Is that roughly what you'd use? Should i add trace minerals too, or maybe just dose those into the tank water as part of weekly fertilisation?

I was thinking of mixing the magnesium, calcium and trace minerals together in the correct ratios to make my own 'RO Right' that i could add to the raw product by measuring a teaspoon (or half) to each 25litres. Do you think this would be feasible/practical?


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## BryceM (Nov 6, 2005)

People here often use pre-made mixes such as Tom Watson's GH Booster or Seachem's Equilibrium. I believe that these contain about a 3:1 or 4:1 ratio. They also contain a good quantitiy of K2SO4, and a bit of manganese and iron.

Personally, I think it would be just as easy to get the bulk chemicals and mix your own. Regarding the other elements, you're probably taking care of this already if you have a good trace element mix.


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