Remineralisation question

[hypnogogia]

Have tried to search for the answer here but couldn't find it. I have two questions:

I remineralise rain water to GH6 with Salty shrimp GH+. Do I Still need to add magnesium to my fertiliser mix or am I OK to assume that remineralising will provide sufficient magnesium for my plants?

Second question is that if I want to reminerlise to GH 6 and KH 1 using dry salts rather than salty shrimp (expensive) what salts will I need?

 

[dw1305]

Hi all,

Second question is that if I want to reminerlise to GH 6 and KH 1 using dry salts rather than salty shrimp (expensive) what salts will I need?

You can use a combination of calcium chloride (CaCl2.nH2O), magnesium sulphate (MgSO4.7H2O) and potassium (bi)carbonate (KHCO3 or K2CO3) to give you any mix of dGH and dKH values you want.

If you don't mind <"dry dosing"> (and I would always recommend it for these salts) calcium sulphate (CaSO4.2H2O) is <"sparingly soluble">, but is an alternative source of dGH.

If you want to make them up <"as stock solutions">, and then dilute them for use, you need to keep the three solutions (CaCl2.2H2O, MgSO4.7H2O & KHCO3) separate, because if you mix them precipitation will occur.

The calculations are at <"James' Planted Tank"> or via the <"IFC calculator">.

I remineralise rain water to GH6 with Salty shrimp GH+. Do I Still need to add magnesium to my fertiliser mix

I'm going to guess you still need a magnesium (Mg) source.

You could ask <"Salty Shrimp"> if their product contains any magnesium. They may reply with an answer, but I'd guess they will hide behind "propriety mix" or some other guff to hide the fact that they are <"charging you pounds"> for <"salts that cost pennies">.

cheers Darrel

 

[hypnogogia]

Thank you.

You can use a combination of calcium chloride (CaCl2.nH2O), magnesium sulphate (MgSO4.7H2O) and potassium (bi)carbonate (KHCO3 or K2CO3) to give you any mix of dGH and dKH values you want.

Presumably I could dry dose those into my rain water at water change once per week?

 

[dw1305]

Hi all,

Presumably I could dry dose those into my rain water at water change once per week?

Yes, you could. Because of <"where you live"> I'm going to say add some magnesium (Mg) via Epsom Salts, and <"some tap water"> for calcium (Ca) and carbonate hardness (dKH).

Because I'm a <"pretty shoddy aquarist">, and always follow the <"path of least resistance">, I just add a <"dash of tap water"> (~17dGH : 17 dKH) into the tank when all the <"snail shells look a bit small and pale">.

I started doing it because it is <"free, easy and quick"> but it actually works really well and you can always call it a <"Planorbella duryi shell bioassay">, rather than a "quick look".

cheers Darrel

 

[hypnogogia]

Because of <"where you live"> I'm going to say add some magnesium (Mg) via Epsom Salts, and <"some tap water"> for calcium (Ca) and carbonate hardness (dKH).

Ok, I will try that. One some final questions, when looking for my tap water KH, do I use the “Hardness (Total) as CaCO3” or “Alkalinity as CaCO3” reading? Does subtracting one from the other give me GH (I.e. Total - KH)

My tap also contains between 4.2 and 5.2 ppm of magnesium.

 

[dw1305]

Hi all,

Hardness (Total) as CaCO3” or “Alkalinity as CaCO3 ....Does subtracting one from the other give me GH (I.e. Total - KH)

I'm going to say you can use either and they should give you about the same figure? Workings are here: <"Water Hardness">, but 1dKH = 17.86 ppm CaCO3 and so does 1 dGH.

My tap also contains between 4.2 and 5.2 ppm of magnesium.

That sounds about right. You would still need to add some, via "Epsom Salts" etc. <"Magnesium (Mg) and water">.

Sea water contains quite a lot of magnesium (Mg), so limestone usually contains some (because of its marine origin). To get water with more magnesium content you need to have rocks (in an aquifer) that formed in an <"evaporite basin">.

cheers Darrel

 

[hypnogogia]

I'm going to say you can use either and they should give you about the same figure? Workings are here: <"Water Hardness">, but 1dKH = 17.86 ppm CaCO3 and so does 1 dGH.

They are two different values on the report: 266 and 182 respectively.

 

[MichaelJ]

Have tried to search for the answer here but couldn't find it. I have two questions:

I remineralise rain water to GH6 with Salty shrimp GH+. Do I Still need to add magnesium to my fertiliser mix or am I OK to assume that remineralising will provide sufficient magnesium for my plants?

Second question is that if I want to reminerlise to GH 6 and KH 1 using dry salts rather than salty shrimp (expensive) what salts will I need?

What Darrel said above...

For GH I use CaSO4 and MgSO4. I run two tanks; one is targeted at 5.5 dGH (got shrimps), and my other tank is aimed at ~2 dGH.
For KH I aim at somewhere around 0.5-1.0 dKH with K2CO3.

If you don't mind <"dry dosing"> (and I would always recommend it for these salts) calcium sulphate (CaSO4.2H2O) is <"sparingly soluble">, but is an alternative source of dGH.

I've been using CaSO4.2H2O for a long time in both my tanks.

The downside of CaSO4 is the low solubility (only 2.6g/l) so it wont work well for very high concentration pre-batching. The positive vs. CaCl2 is that you take on Sulphate rather than Chloride which won't really offer any benefit to your plants and might, according to some, even be problematic. Sulphate - which you will also get a lot of with CaSO4 - is a Macro nutrients while Chloride is a micro nutrient. Either way, your going to take on a lot of both regardless of what you use, but you will get much more Chloride in ppm terms with CaCl2 compared Sulphate when using CaSO4:

For example, to raise your Ca level in dGH terms ~4 degrees:

CaCl2:
Ca 28 ppm
Cl 51 ppm.

CaSO4:
Ca: 28 ppm.
S: 23 ppm.

Cheers,
Michael

 

[dw1305]

Hi all

They are two different values on the report: 266 and 182 respectively.

So 266 / 18, so about 15 I'm guessing that is the dGH and about 10 dKH, I don't know why they are so different.

Cheers Darrel