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How to get RO water to the right gH and kH parameters?

Jamsim

Jamsim

New Member
Joined
17 Jan 2024
Messages
8
Location
Sønderborg, Denmark
Hey everyone,

I have been following a website called aquascapeguide.com where they recommend using Seachem equilibrium to remineralize the water and to obtain the correct gH. For the kH they recommended Baking soda (like arm and hammer).

I have been researching on various threads here and can see that using Seachem equilibrium and baking soda is not recommended.

To give you some context,

My tap water hardness is 15 dH and alkaline. According to the water report the pH is 7.3, Calcium is 95 mg/l and Magnesium is 8.8 mg/l

My RO water has 0 TDS.

I am planning on making my own EI method and realized that if I used mgso4 it would increase my gH over time before my next water change.

So, the question is... what is the best way to remineralize water to obtain the correct water parameters to grow plants and to have fish, snails, and shrimp. I am assuming these values would be around 4 gH and 4 kH? Please enlighten me :) I would love some guidance.

Ive attached the EI calculation ive made.

Thanks!
James
 

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Hi all,
Jamsim said:
So, the question is... what is the best way to remineralize water to obtain the correct water parameters to grow plants and to have fish, snails, and shrimp. I am assuming these values would be around 4 gH and 4 kH? Please enlighten me :) I would love some guidance.
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Subsequently posted in your other thread <"Estimative Index"> (including <"the links">).
Jamsim said:
what is the best way to remineralize water to obtain the correct water parameters to grow plants and to have fish, snails, and shrimp. I am assuming these values would be around 4 gH and 4 kH?
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It depends on the fish, snails and shrimps you use. Most plants are happy at low alkalinity (dKH) values, partially because it makes nutrient availability less problematic. Have a look at @Roland 's <"Soft water tank">.

Cherry Shrimps and snails (like <"Nerites and Assassin Snails">) need harder, more alkaline water (more dGH and dKH), and so do Rift Lake Cichlids etc. most other fish naturally come from softer water. Caradina spp. (Bee shrimps) need soft water.

If you did want to add more dKH and dGH? You can just increase the proportion of tap water. If you want to add calcium (Ca) without adding carbonates? You could use calcium chloride (CaCl2.nH2O) or calcium sulphate (CaSO4.2H2O).

cheers Darrel
 
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Hi all,
Jamsim said:
Yep, just looking for some guidance from smart people like you
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Other members @X3NiTH, @Happi, @_Maq_ are much better at water chemistry (and much more conscientious) than I am.

I'm a <"pretty lazy and shoddy aquarist"> (and scientist), but I've got a <"sceptical mind">, a <"veneer of science knowledge"> and a <"fairly good memory"> and I tend to remember when things <"all went horribly wrong"> and (subsequently) why that particular disaster happened.

cheers Darrel
 
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Jamsim said:
So, the question is... what is the best way to remineralize water to obtain the correct water parameters to grow plants and to have fish, snails, and shrimp. I am assuming these values would be around 4 gH and 4 kH? Please enlighten me :) I would love some guidance.
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IMO use the reminerlising sheet of the IFC calculator , then use the target calculator of the IFC bearing in mind how much other salts you will be using every WC (Water Change) to increase kH and gH. There is a steep learning curve with the IFC, however once mastered it does all the maths for you.
The IFC does all the ppm, kH and gH calculations for all the salts 'mainly used in the hobby. Plus you can clone many commercial ferts, remineralising agents and fert regimes
 
Jamsim said:
For the kH they recommended Baking soda (like arm and hammer).
Click to expand...

Scary that sites like that can be making terrible recommendations like that!

Seachem Equilibrium is fine, but a wastefully expensive way to do it.

Jamsim said:
I am planning on making my own EI method and realized that if I used mgso4 it would increase my gH over time before my next water change.
Click to expand...

Great stuff, so you're already familiarising yourself with mixing salts to make ferts - using them for remineralisation is even easier.

If you are dosing EI, you can forget about KH, no need to worry about that. So for GH you need calcium and magnesium. There are a number of salt you can use, but predominantly Magnesium Sulphate or Magnesium Chloride, and Calcium Chloride and Calcium Sulphate.

Personally I would discount Calcium Sulphate as it has such low solubility, and opt for Calcium Chloride (CaCl2) as conversely it has very high solubility. Magnesium Sulphate (MgSO4) would also be choice on the Magnesium side as its just more readily available (commonly referred to as Epsom Salts) and means less resulting Chloride overall. Just to state the obvious here for completeness, if you plan to use solutions for dosing, you will need to keep them in separate bottles.

How much you add of each salt depends firstly on your livestock choices as Darrel says. If you plan to have shrimp and snails, then you need to aim for around 4-5dGH. The ratio of Calcium to Magnesium isn't hugely important, but 3:1 is often quoted for shrimp, and handily if you add equal weights of CaCl2 and MgSO4, the Ca:Mg ratio comes out pretty much bang on 3:1 which makes life a lot easier. If you don't plan to have any shrimp or snails, then plants and fish only need a trace of calcium, so that can be reduced considerably.

If you want to stick to the EI dosing target of 10ppm for Mg, then 30ppm of Ca (if you have shrimp) will bring you out at about 6.5dGH. Personally I don't think you need to go that high, so I would dial your target back to 7-8ppm Mg, so 21-24ppm Ca for around 4.5-5.2dGH.

Also, given you are remineralising your water change water with Mg, you can then forget about it on the Macro dosing side, and just mix KNO3 and PO4 in your macro bottle.

I hope that all makes sense?
 
@Jamsim

It's best to use combination of CaSO4, CaCl and MgSO4. while CaCl is highly soluble compared to CaSO4, it also adds excess amount of Cl. If I were to pick Cl vs SO4, I would rather have SO4 in little excess. But everyone have their opinions.

Am not a EI user but your Potassium is already covered in KNO3, so no need to add that during mineralization. This is where I do no recommend using seachem equilibrium, their product is simply waste of time and money. The above recommended salts are farily cheap and you can design your GH, Ca, Mg ratio the way you want.

For KH, far as the plant goes, you can keep it at 0. For shrimps, there are various product that raise KH as well as GH.

Many shrimp keeper uses this product:
 

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Hi @Wookii,

I agree with your advice above - can't go wrong with any of that.

Just want to make a couple of points:

Wookii said:
If you want to stick to the EI dosing target of 10ppm for Mg, then 30ppm of Ca (if you have shrimp) will bring you out at about 6.5dGH.
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As an avid shrimp keeper (currently keeping a motley crew of Tangerine, Tiger, Cherry, Bee/Crystal Red) I think a dGH in the 4-6 range is close to ideal (I used to aim for 6 dGH myself for a long time, but slowly dialed it down to 4.5 dGH), at the lower end (4 or perhaps slightly below) you just have to make sure your shrimps have access to mineral rich food supplements. dKH doesn't matter except you should have at least some - I personally aim for 0.5 dKH - I would advice more if your injecting CO2 into a shrimp tank - especially if your tank pH is already at acidic levels.
TDS/EC is just as (if not more) important, hence the reason why I remineralize with compounds that cause the lowest EC impact. Unless you pre-batch your Ca compound where solubility matters, I would advise using CaSO4 instead of CaCl2 as you will avoid the Chloride and also get a considerably lower EC for the same amount of Calcium. Personally, I am taking it a bit further in my shrimp tank (densely planted) by using CaCO3 (for the small amount of Alkalinity/dKH which also adds to the dGH) in combination with CaSO4 and MgSO4 / MgNO3 (for both Mg and N)... My most recent TDS/EC reading was ~85 ppm / ~170 uS/cm. @ 23C. pH 6.2, dGH 4.5, dKH 0.5. Shrimps, snails, fish and plants are seemingly doing great!

Cheers,
Michael
 
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If whatever Kyle said is true, then we still don't need to use seachem equilibrium and sodium bicarbonate to boost GH and KH. You still have a better option which is Cacl, CaSO4 and MgSO4 for GH and KHCO3 for KH, but again this will also raise the K to significant number. Sodium isn't essential for plants and can only harm them in excessive levels, so I don't see the benefit from it just to raise little KH.

Most shrimps substrates now days are designed to eat away the KH for whatever reason. Most people are already in the ph range of 5-6 and likely been keeping the shrimps in such ph for some times now.
 
MichaelJ said:
dKH doesn't matter except you should have at least some - I personally aim for 0.5 dKH - I would advice more if your injecting CO2 into a shrimp tank - especially if your tank pH is already at acidic levels.
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Just by way of another data point, I've not added any carbonates to my CO2 injected, RO based tanks for a number of years now without any issues. I always dose a fair bit of PO4 (1ppm minimum), so maybe that's providing sufficient buffer but I don't see any need to elevate KH.
 
Wookii said:
Just by way of another data point, I've not added any carbonates to my CO2 injected, RO based tanks for a number of years now without any issues. I always dose a fair bit of PO4 (1ppm minimum), so maybe that's providing sufficient buffer but I don't see any need to elevate KH.
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Interesting that, around the phosphate. What is the pH of the water in the tank after all is said and done? You will have the same amount of carbonates in the water from equilibrium with both atmospheric CO2 and injected CO2 whether you add them deliberately or not - just the degree to which they are protonated will change and that is dependent on pH. If you provided e.g. KH2PO4 as your source of phosphate (which would be typical), then between pH 6-7 (where I'm guessing you are) you'll mostly have H2PO4- and K+ which is to say the phosphate won't go grabbing protons from your carbonate species so won't mess with the equilibrium distribution of H2CO3/HCO3-/CO3--. In that state, the phosphate will provide good buffering capacity against increasing pH as the phosphate converts from H2PO4- to HPO4-- with increasing pH (50/50 ratio at pH 7.2) so can release protons to counter a pH rise, but won't provide any meaningful buffering capacity against decreasing pH since the phosphate won't start grabbing extra protons (converting from H2PO4- to H3PO4) until the pH gets well below 3.

Now that I reflect more upon it, no one ever needs to "add KH" - the pH of the water (however you regulate pH) and atmospheric CO2 will do that for you. Excess carbonate (for a given pH) will be outgassed as CO2, and insufficient carbonate (again for a given pH) will be provided by conversion of atmospheric CO2.
 
Andy Pierce said:
What is the pH of the water in the tank after all is said and done?
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Good question, to be honest I’ve not measured it in a long time, so just dug out my pH meter.

My main tank, which is CO2 injected but only to a target of around 10-15ppm - pH is current sitting at about 5.5pH mid-photo period - zero carbonates added (RO water comes out around 6ppm, so there could be a tiny trace in there - though tap water has a lot of other minerals in it too inc 6dKH and 11dGH etc).

I dose 1.5ppm PO4 on this tank.

IMG_4614.jpeg
 
Andy Pierce said:
What is the pH of the water in the tank after all is said and done? You will have the same amount of carbonates in the water from equilibrium with both atmospheric CO2 and injected CO2 whether you add them deliberately or not
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I'm guessing it's a moving feast. Currently drop the ph to 5.6, degassed ph is 6.8. Estimated dkh 0.6 With a 1ph drop in soft water I maybe have 15ppm CO2.
 
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Wookii said:
Good question, to be honest I’ve not measured it in a long time, so just dug out my pH meter.

My main tank, which is CO2 injected but only to a target of around 10-15ppm - pH is current sitting at about 5.5pH mid-photo period - zero carbonates added (RO water comes out around 6ppm, so there could be a tiny trace in there - though tap water has a lot of other minerals in it too inc 6dKH and 11dGH etc).

I dose 1.5ppm PO4 on this tank.

View attachment 215000
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Nice tank. Are those Week Aqua T90 lights? Do you find them to be blinding when hung so high since I assume they must shine into your eyes when you're viewing the tank up close?

Thanks,
Harry
 
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