How much calcium & magnesium

[_Maq_]

using pure RO water is not a good idea

Just to clarify: I'm using RO+DI water exclusively and mineralize it according to my needs. I too enjoy full control over all parameters. And don't have to ask anyone how to do it, so you may suppose I know something about it.
Here, there's a newbie who's asking trivial questions about how to make RO water hard. Because of that, I'm encouraging him to go to the roots and reveal if he even knows what kind of water he needs and why.

 

[Nick potts]

And don't have to ask anyone how to do it, so you may suppose I know something about it.
Here, there's a newbie who's asking trivial questions

Thats nice that you don't need help, but not everyone is the same, and if "newbies" stopped asking "trivial" questions this forum would cease to exist in a short time.

The OP has asked how much powder he needs to reach a GH of 6 ( a reasonable a number as any), no need to dive into the minutiae of everything all the time.

 

[Tonyball]

You might want to read again what I said about solubility above. You said you wanted to prepare a solution with CaSO4 and MgSO4 and then dose that in the tank. It's not possible due to solubility limits. Or perhaps I mis read you.
The advice is to dry dose instead or use CaCl2 instead. You have multiple choices.

Sorry I was going to mix them both in separate bottles, so a 500ml bottle with just mgso4 and a 500ml bottle with just caso4..
then add to the ro water as needed..

I didn't no I cud just add the powder direct to the ro water like nick said, I didn't no that..

I will do what nick said as that sounds right?

 

[MichaelJ]

My question was meant 'why bother making RO water when your intention is to have it hard, anyway'.

Using RO water or rain water has a lot of merit even of you remineralize it make it quite a bit harder. It takes the guess work about your tap water parameters out of the equation. Tap water parameters can fluctuate throughout the year and your water report wont tell you exactly what is coming out of your tap even if your water report is seemingly "perfect". Anyway, perfect tap water is a rarity anyway. In my shrimp tank I couldn't use my straight tap even if I wanted - its way too hard (+20 GH and possibly high copper contents - possibly borderlining lethal levels for the shrimp, not to mention a TDS that would be problematic for the shrimps as well). Thats why I use RO water in my shrimp tank remineralized to ~5 GH and ~0.5 KH. Good for shrimps good for plants!

The plants don't need it, they are fine on a much lower GH target, but the shrimp certainly do. Depending on the shrimp you could drop it a bit, maybe GH4-5.

Agree!

To echo @Nick potts point, CaSO4 is fairly difficult to dissolve, you'd be better with CaCl2 (Calcium Chloride).

For my WC water I am using 20 Liter mixing buckets. In the buckets the targeted 21 ppm of Ca with CaSO4 is very easy to dissolve. For my Ca target of 21 ppm I get 17 ppm of SO4, If I would use CaCl2 I would get 39 ppm of Cl... I highly recommend CaSO4 if you can mix it in on the fly - if you want the convenience of pre-batching in smaller bottles CaCl2 is likely your only choice due to the high solubility. Either way, you are going to take on elements your plants wont need in excess be it SO4 or Cl, but at the end of the day the high levels of Sulphate is less problematic for your plants than the Chloride.

Cheers,
Michael

 

[Hanuman]

Sorry I was going to mix them both in separate bottles, so a 500ml bottle with just mgso4 and a 500ml bottle with just caso4..
then add to the ro water as needed..

I didn't no I cud just add the powder direct to the ro water like nick said, I didn't no that..

I will do what nick said as that sounds right?

Yes dry dosing that's what most people do. That's what I do as well.

 

[_Maq_]

this forum would cease to exist in a short time.

The OP has asked how much powder he needs to reach a GH of 6 ( a reasonable a number as any), no need to dive into the minutiae of everything all the time.

Well, and I thought differently. I sensed a newbie, and attempted to enter broader discussion so that he could get as much information as possible, incl. some he even does not ask for. Because he's a newbie, he may surely benefit from that.
A curt reply "add 145.67 mg/l CaSO4" would also be a reply even if forgetting about the minutiae of hydratation...

 

[MichaelJ]

Hi I've just brought some caso4 & mgso4 powder for raising my GH of ro water..

I change 50l per week...

So when mixed in a 500ml bottle of water 1 mil per 50l adds 0.5mg/l magnesium

And 1mil per 50l adds 0.6 mg/l calcium

I want to make the 50l of ro water a GH of around 6

How much of each in mil? do I need to add to achieve that GH of 6

I haven't a clue 😄

Thanks I'm advance

Hi @Tonyball ,


To answer your original question:

For your 50 liter of WC water:

Adding 5 Grams of CaSO4 will give you 23 ppm of Ca
Adding 4 Grams of MgSO4 wil give you 8 ppm of Mg

For a total of 5 GH.

Perfect for your shrimps!

Cheers,
Michael

 

[Tonyball]

Hi @Tonyball ,


To answer your original question:

For your 50 liter of WC water:

Adding 5 Grams of CaSO4 will give you 23 ppm of Ca
Adding 4 Grams of MgSO4 wil give you 8 ppm of Mg

For a total of 5 GH.

Perfect for your shrimps!

Cheers,
Michael

Thanks this is the answer I was looking for , as I said am new to this and the instructions on the packet said to add the contents to 500ml of water..

I was going to mix a 500ml bottle for cas04

And a 500ml bottle for mgs04

And add a certain amount of each in ml to get the correct GH

I will just do what u recommend as that sounds much easier..

Many thanks 😊 we got there in the end 😝

 

[Tonyball]

cas04 and mgs04 are fine to use, you just won't be able to mix the cas04 in a 500ml container, it just won't dissolve, add the powders directly to your 50ltrs or RO and you'll be fine.

Sorry, my calcs where off, I did 50 gals, not liters, 4.5g of CaSO4 and 5g of MgSO4 will give you around 5.2 GH which is plenty for plants and shrimp, mine is much lower and my shrimp are doing fine, but i do feed a lot of mineral foods.

Thank you 😊

 

[dw1305]

Hi all,

My tap water is unusable..

If it is hard, alkaline tap water? It doesn't really matter if it is high in nitrate (NO3-) & phosphate (PO4---), because you are only going to be mixing a small volume with your RO water.

UK tap water doesn't contain any heavy metals, (EU) regulations are <"still really tight on these">. Once the <"BREXIT bonus"> kicks in? Things may change.

The only times when you couldn't use <"tap water as a remineralising agent"> are if your tap water is naturally soft or if it runs through <"an ion exchange unit">.

I've just brought some caso4 & mgso4 powder for raising my GH of ro water.. I change 50l per week...

I've already brought the stuff, just need to know the correct amounts to add..

Simple enough, you will need to dry dose because of the <"limited solubility"> of calcium sulphate dihydrate (CaSO4.2H2O). @_Maq_ has written a very useful article for UKAPS <"Some handy facts about water">.

Edit: I just do what @MichaelJ <"recommends">

From that the bits we need are:
Ca++: 1 mg / L = 0.14 °dGH
Mg++: 1 mg / L = 0.23 °dGH

which<"is equivalent to"> :
1 dGH = 7.14 mg/ L Ca++
1 dGH = 4.35 mg / L Mg++

I'm going to go for 1 : 1 Ca : Mg, so to get 6 dGH in 50 litres of RO:

We need 7.14 x 50 = 357 and 357 x 3 = 1071 mg and 1071 / 1000 = 1.071 g of Ca++ and CaSO4.2H20 is 23% Ca++ so 1.071 / 0.23 = 4.66g CaCO4.2H20 in 50 litres of RO water gives you 3 dGH, all calcium. The magnesium is the same calculation, but the numbers now are 4.35 and 10% giving you 6.53 g of MgSO4.7H2O.

I'm a rainwater user and personally I'm going <"to use a bit of tap"> water to give me some calcium (Ca) and (bi)carbonate (2HCO3-) and <"a sprinkle of "Epsom salts"> to add some extra magnesium. I used to measure conductivity, but now I just use the <"state of the snail shells"> to estimate alkalinity and hardness.

The bit you don't need
The <"water of crystallization"> changes the percentage of calcium (Ca) and magnesium (Mg) in each salt, so MgSO4.7H2O is only 10% magnesium and CaSO4.2H2O (40 / 172) 23% calcium. It is those percentages that allow us to work out the hardness (dGH) addition.

The maths is a bit strange, because dGH is a funny measurement, but they are here: <"Water report">.

cheers Darrel

 

[MichaelJ]

I will just do what u recommend as that sounds much easier..

Yes, don't make simple things complicated.... With a GH of 5 with Ca:Mg at a 3:1 ratio you will not go wrong. Darrel's post above nicely shows how the math works if you want to tweak things a bit.

Cheers,
Michael