Dosing General Hardness

Gill Man

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Feb 10, 2005
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I have a question regarding GH and dosing Mg and Ca. Is anyone using either Seachem's or Kent's GH+? I checked Kent's website to see if they gave ratio of Ca to Mg. the MSDS link, http://www.kentmarine.com/msds/BOTANICA_GH.PDF shows < 20% for each component, which I take to mean that their solution is variable.

I have both these chems available separately, but wanted to use up the rest of the 2L container. I go through about 100ml per week after w/c for my 90G for a GH of about 5 dKH.

I know we're looking to sustain a 4:1 ratio, Ca to Mg, but I don't remember reading why. I know some people add MgSO4 to their CSM+B mix, doesn't this change the 4:1 ratio and do they then add back Calcium?

I'm not worried about maintaining a steady dGH, knowing it can go up some without any problems, but I would like to get a handle on how to dose these two cations during the rest of the week. Also, if anyone has any "tricks" to dissolving calcium, please let us know! I have been thinking about gettting a stir plate, perhaps even with heat, to have it all mixing without having to attend to it. Thanks.

If your responses could reference dGH instead of ppm that would be great.
 

Ian H

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Jan 24, 2005
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Shipley, West Yorkshire, UK
Re: Dosing General Hardness

My tapwater is quite soft and low in Gh. Although I can't answer your question with any authority I'll be lurking on this thread as I need to understand the importance of the chemicals that constitute permanent hardness and their effect on plant growth.

Ian
 

fosteder

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Feb 3, 2005
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Rochester, NH
Re: Dosing General Hardness

About dissolving CA....CaCO3 is a pain in the rear to dissolve. I have heard that CaCl2 dissolves much easier. I will be able to tell you how easy in a few days, I have a shipment coming in from www.GregWatson.com
 

chubasco

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Jan 24, 2005
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Re: Dosing General Hardness

I have both these chems available separately, but wanted to use up the rest of the 2L container. I go through about 100ml per week after w/c for my 90G for a GH of about 5 dKH.

This GH+ also has carbonates/bicarbonates in it to boost your KH? Your above
statement doesn't make sense unless it does. GH is sulfates and chlorides
which you get from Epsom salt (MgSO4) and Calcium Chloride. Carbonate
hardness (temporary hardness) is from carbonates/bicarbonates where most
of us just use baking soda (sodium bicarbonate) to raise it's level to 5 dKH. I
don't want to be pedantic on stuff you already know, but do you have the
water report from your city or county? That'll be your baseline for what needs
to be added. There's people that run their tanks with 10-12 dGH with great
results, but you have to have at least 5 dKH to go with that. The 4:1 ratio
of Ca to Mg is for good cell transport, both plants and fish. You have to keep
track of what the tapwater has already (Ca&Mg) and treat your changewater
with it, not the tank. I'm for fert the tank, but treat the changewater for
whatever parameters, it needs, separately. That dispenses with any mistaken
overlap. YMMV,

Bill
 

Gill Man

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Re: Dosing General Hardness

My bad (first time ever using this slang). I meant 5 dGH. According to the packaging and website, Kent's GH+ contains magnesium and calcium salts, which, I guess could be anything including CaCl2, CaCO3, MgSO4, etc. I was wondering if I need to add calcium back into the tank if I'm adding MgSO4 along with my CSM+B. Sounds like it, to get close to a 4:1 ratio.
 

chubasco

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Jan 24, 2005
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Re: Dosing General Hardness

I myself wouldn't add MgSO4 with the CSM+B to the tank. I'd do a test for
GH then add Ca/Mg 4:1 to bring it up to at least 7 dGH. That way, the 2
components are in proper ratio, tho I don't know if this is an absolute, maybe
3:1 would be adequate, too. As I said before, I like to keep water treatment
and water column fertilization separate, so I don't mistakenly double up on
one or more components.

Bill
 

Laith

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Jan 24, 2005
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Re: Dosing General Hardness

My tap water is a bit ridiculous when it comes to GH. I have a GH of 14 out of the tap but the vast majority of it is Calcium... very little Magnesium.

It took me a while to figure out that my plants needed more Magnesium even with a GH of 14 out of the tap.

As to Calcium, CaCl2 dissolves readily in water.
 

Tom Barr

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Jan 23, 2005
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Re: Dosing General Hardness

CaCl2 for Ca
MgSO4 for S and Mg
CacO3 for both Ca and KH
Baking soda for KH

SeaChem Equilibrium for Ca, Mg, K, Fe, Mn
It's a good product for many things and very useful for non CO2 tanks when dosed once a week.

Regards,
'Tom Barr
 

chubasco

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Jan 24, 2005
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Re: Dosing General Hardness

As to Calcium, CaCl2 dissolves readily in water.

I concur, after placing three 1/8" chips of Greg's Calcium CaCl2 in a
half-filled beaker of water: with gentle swirling it completely dissolved in
 

Ian H

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Jan 24, 2005
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Shipley, West Yorkshire, UK
Re: Dosing General Hardness

OK all well and good, but how do I know if my tank is deficient in calcium and magnesium? And what is this 4 to 1 ratio about and how do I calculate and achieve that, if I need to.

Ian
 

chubasco

Guru Class Expert
Jan 24, 2005
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Re: Dosing General Hardness

Ian, you will have to do a GH test on your water to find if you're deficient in
Ca and Mg. That won't separate into whether it's Ca or Mg, so having the
water report from your water company is helpful. If it shows that you have
a predominant quantity of one or the other, you will have to factor accordingly
:)

Can you guys in Europe get these water reports? Or has the government decided you don't need to know the "accepted level" of arsenic, cyanide, and
the like. When I was stationed in Fallon, Nevada, cyanide was 10% above its
"accepted level." I drank bottled water judiciously, while there....

Bill
 

Gill Man

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Re: Dosing General Hardness

Since my first posting, I started using my new La Motte CaCO3 test. With this value and dGH and formulae, I can calculate Ca and Mg concentrations. After my 70% waterchange, I got a calculated value of 15.2 ppm Ca and 7.41 ppm Mg. I added enough CaCo3 to increase my Ca to about 30 ppm, so now I have 4:1 ratio of Ca:Mg. It also increased my GH by about 1 dGH and Kh to 2.25 dKH. Which is exactly what I was looking for in my dosing general hardness post.

I understand my test kit only measures CaCO3 and not Ca but it gives me the approximation I was looking for without dosing Ca and Mg too blindly.
 

chubasco

Guru Class Expert
Jan 24, 2005
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Re: Dosing General Hardness

How much does a La Motte CaCO3 test, cost? Being able to separate the 2
in measurements is a handy tool!

Bill
 

Gill Man

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Re: Dosing General Hardness

Ok, so I just did a KH test and it is the same as before I added the CaCO3, so I feel confident to say that adding CaCO3 does nothing to raise KH.
 

Roman

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Jan 23, 2005
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Re: Dosing General Hardness

bill ruyle said:
Can you guys in Europe get these water reports? Or has the government decided you don't need to know the "accepted level" of arsenic, cyanide, and
the like. When I was stationed in Fallon, Nevada, cyanide was 10% above its
"accepted level." I drank bottled water judiciously, while there....

Bill


I don't know for the rest of the Europe, but here in Slovenia I can get water report, but there is no Ca or Mg in it :mad:
You can check it here, it's in pdf format. I guess I'll need to ask them for Ca and Mg, but I somehow doubt about getting answer.

There is like 14 mg/l SO4 and 6 mg/l Cl, but I don't know if this information is of any value.

Roman
 

Laith

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Jan 24, 2005
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Re: Dosing General Hardness

Gill Man said:
Ok, so I just did a KH test and it is the same as before I added the CaCO3, so I feel confident to say that adding CaCO3 does nothing to raise KH.

The carbonates in CaCO3 will raise your KH... eventually! It just takes that stuff forever to dissolve and impact KH and GH.

Baking soda (sodium bicarbonate) dissolves immediately and has an instant impact on KH without affecting GH.
 

Nillo

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Jan 24, 2005
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Re: Dosing General Hardness

Doesn't baking soda impact pH? Would you need to make up the water well in advance?
 

Gill Man

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Feb 10, 2005
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Re: Dosing General Hardness

It raised my GH after a few hours. Why wouldn't it be measurable in a hardness test immediately? I understand the KH part, how it will increase slowly over time as it dissociates.

I did adjust the KH with sodium bicarbonate. I just stir 2 tsp. in glass of water then dump it in the tank (90G). pH goes up a littel as we would expect. Once the ph controller brings down the pH (about 5 minutes later) I add another aliquot and repeat until I get to my KH target level. I've been doing it this way for years. If it takes that long for CaCO3 to dissociate, then I'm not gonna worry about it. :D
 

alexperez

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Jan 24, 2005
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Re: Dosing General Hardness

Gill Man,

I quote "Since my first posting, I started using my new La Motte CaCO3 test. With this value and dGH and formulae, I can calculate Ca and Mg concentrations."

Could you tell me how you did that?
I have the La Motte Hardness(4824-DR-LT) and the La Motte Alkalinity (4491-DR) are these the same test kits you have?

Thanks!