A few qs about GH BOOSTER

Hi all,

I want to make my own GH booster. So do I just use MgS04 and CaS04 and if so, in what ratio?

Also I've always used Tropica Trace (as mixing my macro ferts is enough of a faff on for me without making up trace as well) but found a bargain on Flourish trace so bought a huge bottle. But have discovered that this does not contain iron. So should i get some FeS04 and add this with MgS04 and CaS04?

Or anyone reccommend a cheapish gh booster that doesnt add loads of K?

Thanks
Julia

Hi,
GH booster recipes are not really anything special. I've seen ratios like 3:1 of CaCO3 to MgSO4, but just about any ratio you use will be good.

To make sense of the ratios, one has to start with the quantity of Mg in MgSO4 and the quantity of Ca in CaSO4.

Here is the mass composition by weight of Epsom Salts:
---------Element-----------Atomic Weight---------# of Atoms--------Mass % by Weight
Mg-----Magnesium----------24.3----------------------------1-----------------20.2%
S-------Sulfur------------------32.1----------------------------1-----------------26.6%
O-------Oxygen---------------16------ ------------------------4-----------------53.2%

So 20% of any mass of MgSO4 is Mg. That means adding 10 grams of MgSO4 to a volume of water in effect adds roughly 2 grams of Mg and roughly 8 grams of SO4. If we add 10 grams of MgSO4 to a litre of water, the Mg concentration would then be 2 grams per litre. 2 grams is the same as 2000 milligrams, right? So that would mean 2000mg/L or 2000ppm.

Adding 10 grams of MgSO4 to 100L means the concentration would be 100 times weaker, or 20 ppm.

We can do the same analysis with CaSO4, Calcium being the salient element for GH.
---------Element-----------Atomic Weight---------# of Atoms--------Mass % by Weight
Ca-----Calcium----------40.0784----------------------------1-----------------29.4%
S------Sulfur --------------32.0655----------------------------1-----------------23.6%
O-----Oxygen------------15.99943----------------------------4-----------------47%

As you can see, Calcium comprises roughly 30% by weight of the CaSO4 molecule. Adding 10 grams of CaSO4 to an arbitrary volume of water adds 3 grams of Ca. So 10 grams of this compound added to 100L of water, doing similar arithmetic means a Ca concentration of 3000mg/100L = 30ppm Ca.

The problems is GH is defined as 1 millimole of calcium (either Ca2+ or CaCO3) per litre of water = 100.09 ppm or 5.608 dGH, since the molar mass of CaCO3 is 100.09 grams per mole. This makes it really difficult to determine the GH when you have a combination of Mg and Ca compounds in the water. That's because you have to calculate the molar equivalence of the two compounds with respect to the molar weight of CaCO3. This really makes things messy so I just borrow a formula given some time ago by Barr:
[(4.1 x the Mg ppm) + (2.5 x the Ca ppm)]/17.86 = German Degrees (dGH), which is what most GH test kits show.

10 grams of MgSO4 + 10 grams of CaSO4 added to 100L of water would give:
[4.1 x (20 Mg ppm) + 2.5 x (30 Ca ppm)]/17.86 = 8.8 GH

Having these numbers allows you to do make any mixture you want but this transparency now raises the issue of why one needs to make up a GH booster in the first place. The fact of the matter is that adding GH just for GH's sake is a meaningless endeavour. What we are really trying to do is to add sufficient quantities of Mg so that the plant does not suffer an Mg deficiency. We add sufficient Ca so that the plant does not suffer a Ca deficiency. It just so happens that the parameter we call "GH" is just a measurement of the waters Mg and Ca content. One only needs a few ppm of each. If your water is already high in one then just add the other. If using RO/DI or soft tap water then just add enough, in roughly equal quantities to raise the GH to about 3 or 4 and call it good. Even at that you'll have way more of Mg or Ca than you need.

Iron Sulfate analysis looks like this:
---------Element-----------Atomic Weight---------# of Atoms--------Mass % by Weight
Fe-----Iron------------------55.8--------------------------------1--------------36.7%
S-----Sulfur------------------32---------------------------------1-----------------21.1%
O-----Oxygen-----------------16-------------------------------4-----------------42.1%

So almost 40% by weight of the FeSO4 is Iron. 10 grams of FeSO4 added to 100L of water will add 4 grams of Fe and this will be 4000mg/100L = 40ppm. Since the suggested concentration is only 0.5 ppm Fe So you only need just over a tenth of a gram (0.125g) in 100L to get the recommended dosage. It might be better to simply chuck some FeSO4 into the bottle of flourish trace.

Cheers,

Hi all,
The other thing you need to think about is that calcium sulphate is not very soluble. So what you will end up with is a saturated solution and some un-dissolved compound if you add more of the compound than c. 2.5g/L.

Calcium sulphate solubility.
2.1 g/L (20 °C, anhydrous) CaSO4
2.4 g/L (20 °C, dihydrate) CaSO4.2H2O

Also you need to take into account the "water of crystallisation" - MgSO4.7H2O, have a look at the "magnesium sulphate" thread for the details.

I'd probably use the recipe from James' Planted Tank: <http://www.theplantedtank.co.uk/water.htm>
Adding 3.0g Sodium Bicarbonate (NaHCO3) to 100 litres of water will raise the alkalinity by 1
Adding 3.6g Potassium Bicarbonate (KHCO3) to 100 litres of water will raise the alkalinity by 1

Adding 3.1g of Calcium Sulphate dihydrate (CaSO4.2H2O) to 100 litres of water will raise the GH by 1
Adding 4.4g of Magnesium Sulphate heptahydrate (MgSO4.7H2O) to 100 litres of water will raise the GH by 1

cheers Darrel

Yes, another alternative to the sulfate is Calcium Chloride (CaCl2) which practically melts on it's own.

Cheers,

Thx for the replies guys. Thats really helpful!

Ok thanks guys, ive got my mg and ca in. Now question is how often should i add it - I know this depends on a lot of things but I have no idea how quickly plants will use this up - so add with weekly wc or add every other day with NPK.

Cheers
Julia

Weekly should be fine, but if it's easier to mix it in with the other ferts then do that. Basically do whatever makes life easier for you.

Cheers,

Since the suggested concentration is only 0.5 ppm Fe So you only need just over a tenth of a gram (0.125g) in 100L to get the recommended dosage. It might be better to simply chuck some FeSO4 into the bottle of flourish trace.

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Had a break from planted tanks since moving house, but Im setting up again.
Ive needed to rack my brain a bit to recall how I made my ferts up. Then I remembered the wonders of the 'view your posts' function on the forum.

So I have about 3l of flourish trace which I believe doesn't have iron in (although can't quite believe they would make a trace without iron). Ceg said I should throw a bit of Fe into the bottle. But Im not sure how much to Fe add. Im dosing 25ml of trace every other day. Don't want to waste it and be dosing way too much, and definitely want to be dosing enough.
Can anyone help me out?
Thanks
Julia

Sorry to bump up an old thread; but i am using Duradrakon to enrich my R/O water. I'm aiming for about a KH of 3.5 and GH of 5-6. Problem is that Duradrakon on its own adds both KH and GH to the water. So upping the KH to 3.5KH equals adding only 4.5GH. For this i need to add 12.6 grams of Duradrakon per 100l; giving concentrations of 21.7 mg/l Ca and 6.6 mg/l Mg (Ca:Mg ratio of 3.25:1) I could add 3.1 grams of CaSO4.2H2O to the mix, which makes me end up at the target values, but is that really needed? Am i staring blind on numbers and ratio's?

Especially seeing Ceg mentioning:

ceg4048 said:

The fact of the matter is that adding GH just for GH's sake is a meaningless endeavour. What we are really trying to do is to add sufficient quantities of Mg so that the plant does not suffer an Mg deficiency. We add sufficient Ca so that the plant does not suffer a Ca deficiency. It just so happens that the parameter we call "GH" is just a measurement of the waters Mg and Ca content. One only needs a few ppm of each.

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Hi all,

Gilles said:

I could add 3.1 grams of CaSO4.2H2O to the mix, which makes me end up at the target values, but is that really needed? Am i staring blind on numbers and ratio's?

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That will work. It isn't going to do any harm, so I wouldn't worry too much about the actual numbers.

I wasn't familiar with the Duradrakon RO salt, but it looks quite a good mix, without too much sodium (Na) in it.

If you want to make your own re-mineralising salt you can just use potassium bicarbonate (KHCO3), "Epsom Salts" (MgSO4.7H2O) and calcium sulphate (CaSO4.2H2O) (or calcium chloride (CaCl)), you don't need to add any sodium (Na), and all the chemicals are available cheaply.

cheers Darrel

Well based on my e-mail conversations with Marcel Goliaš (who has an excellent Nature Aquarium website on all things related to water, nutrients and chemistry) i've come up with a little tool. I've created an Excel sheet in which i can enter my target KH and GH and it will calculate the amount of Duradrakon, CaSO4 and MgSO4 to add per 100L to get the concentrations in the target.



Basically it only uses the target KH to get the amount of Duradrakon to add, and determines the amount of Ca, Mg and GH that DuraDrakon adds. Then it finds out how much Ca you still need to add to come close to the ratio mentioned on Marcels website (recommended values of Ca2+ (30 mg/l) and Mg2+ (10 mg/l)). This results in more Ca and GH being added.

Finally it uses the Ca:Mg ratio of Duradrakon (3.25:1) to calculate the remaining Mg to add to get both close to the target values AND to get the ratio correct.

I have no way to upload this excel sheet publicly, but i am willing to share if requested.

Gilles said:

is that really needed?

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No.

Gilles said:

Am i staring blind on numbers and ratio's?

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Yes.

The main problem in this hobby is that people complicate the very simple things and they oversimplify the very complicated things. That's what causes blindness.

Calcium and Magnesium are trace elements Do people realize what this means? It means they only need a trace of the element to be present. It just has to be non-zero. A plant needs somewhere between 500X-1000X more Carbon than it needs Magnesium or Calcium. That's why they are referred to as "micro" nutrients.

As Darrel mentions, you can remineralize by purchasing your own salts for about 100X cheaper than the product you linked to. You don't need spreadsheets or target value calculations or ratio analysis. Just grab a few teaspoons and chuck them into the tank or into your mix.

Cheers,

Ok, got it. So i was looking at this page; and given the information in that thread they say;

Here is the formula to the recipe that that will provide a 2 degree increase (37 mg/l) of both KH and GH in 100 litres of water.

7.2g KHCO3 (Potassium bicarbonate)
3.3g CaSO4.0.5H20 (Calcium sulphate hemihydrate)
3.3g MgSO4.7H20 (Magnesium sulphate heptahydrate)
13.8g total in 100 litres

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Assuming the above percentages are correct;
3.3g CaSO4 results in 6.666 mg/l Mg
3.3g MgSO3 results in 9.702 mg/l Ca

So when i calculate the given grams with the formula above;
[4.1 x (6.666 Mg ppm) + 2.5 x (9.702 Ca ppm)]/17.86 = 2.88 GH

Which is more then he claims that the solution adds.. Is his concentration wrong?

Hi all,
I'd need to to do the calculations, but I think the problem is probably the derivation of dGH/dKH. They are expressed in a slightly strange way where you look at them as CaCO3/CaO equivalents.

Agreed that it would make much more sense to express everything as ppm (mg/l). Have a look here: <http://www.thekrib.com/Plants/CO2/hardness-larryfrank.html>.

This is the bit you need to work out dGH/dKH

........1 dGH is defined as 10 milligrams (mg) calcium oxide (CaO) per litre of water, which is equivalent to 0.17832 mmol per litre of elemental calcium and/or magnesium ions, since CaO has a molar mass of 56.0778 g/mol. 1 dGH corresponds to 17.848 ppm, since CaCO3 has a molar mass of 100.0875 g/mol......

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and

One German degree of carbonate hardness (dKH) corresponds to the carbonate and bicarbonate ions found in a solution of approximately 17.848 milligrams calcium carbonate (CaCO3) per litre of water. Both measurements (mg/L or KH) are usually expressed "as CaCO3" – meaning the concentration of carbonate expressed as if calcium carbonate were the sole source of carbonate ions. Bicarbonate ions only contribute half as much carbonate hardness as carbonate ions, so bicarbonates that are present in the water are converted to an equivalent concentration of carbonates when determining KH.

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cheers Darrel