View Full Version : Alk and Ca

07/28/2017, 06:00 AM
Hey, im starting 2 part dosing and the instructions on the manufacturer says following:

(mix 2kg with 5 liters of ro water) and 50ml of the solution should raise Ca by 10ppm for 1000l of water

(mix 500g with 5 liters of ro water) and 50ml of the solution should raise Alk by 0,2 dKH for 1000l of water

This cant be balanced mixing recipe can it to add equal ammounts of both solutions? So here I need help: what ratio should i add these to avoid any ionic imbalance?
(Note to self:Clearly I should have stayed in my confort zone with pre mixed liquids...) And since English isn't my first language, alot of Randy's articles are like jibberish to me. In most if not every article Randy points out "add equal ammounts of CA and Alk". And heres my problem, couldn't figure out if the equal ammounts is ment by liquid weight when fully saturated, dry weight of the powders or by what means "equal" because the saturation of the solution has to play a part in this right?


07/28/2017, 10:31 AM
"Equal amount" refers to the liquid volume while dosing.

This is assuming the alkalinity and the calcium solutions you made were purchased from the same manufacturers. Different manufacturers sell different strength products.

You don't have to dose equal amounts though. That's what makes two-part dosing better than a calcium reactor. With a two-part dosing, you can adjust the dosing volume of either calcium or alkalinity based on your system's needs.

The link below shows the relative ranges. Pick an alkalinity range you like and make sure your calcium is within the range in that line.

Good luck!


07/28/2017, 11:31 AM
I use Randys diy 2 part recipe 2 (http://www.reefkeeping.com/issues/2006-02/rhf) 250gms Calcium Chloride in 5 litres, and 297gms Baking Soda in 5 litres use his calculator too what tank you have. I was dosing 1ml of each to start per gallon, but over the year have amended both with increased coral demand

Martin Kuhn
07/28/2017, 12:03 PM
In case you like to dose "balanced" (what I don't really recommend! )

For this recipe you need to calculate/apply your dose for Alk and decide by 4,6. this would be your "balanced dose" of Ca.

A) in order to be able to calculate the correct amount of your stock solution proceed like this for mixing: ~ 50% of the volume of RODI water. Then add the given weight of salt. Mix. Then filling up to 100% ( here 5 Liter). Mix
B) 500 g/Liter NaCO3 is over the maximum saturation of this salt. You might have problems to get this mixed.
Which company / product does recommmend this ?
A "typical" solution is reached if you mix 400 instead of 500g up to 5 Liter (=80%)
If you do so...... the needed amount of this Stock solution is also higher ! ( given amount / 0,8 )

Best Rgds

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07/28/2017, 05:15 PM
I think Martin meant "divide by 4,6", which sounds about right. The calcium dose should be much smaller given the concentration of the solution.

Martin Kuhn
07/28/2017, 11:45 PM
Thx Jonathan, for correcting my (iOS-AutoCorrection) typo.
You are right, i wanted to write "divide" of course.

i also checked the recipes capability to raise Alk in the meantime.
("(mix 500g with 5 liters of ro water) and 50ml of the solution should raise Alk by 0,2 dKH for 1000l of water

50ml @1000L watervolume -> 0,2 dKH is the same as
250ml @1000L -> 1,0 dKH and thus identical to
25ml @100L -> 1,0 dKH
This is not correct in my eyes.
@Rami: Could you please tell us which manufacturer recommended this recipe/dosing?

-> Here you go with the correct data
a) Original recipe
a1) 500g NaHCO3 (baking soda) mixed with RODI water up to a 5 liter stocksolution
- Alk: 30ml @100L -> 1,0 dKH (not 25 ml)
Solution is over saturated!
a2) 2000g CaCl2 2xH2O (Calcium-Chlorid DiHydrate) mixed with RODI water up to a 5 liter stocksolution
- Balanced Ca dosing (Ca +7,13 mg/l) : 6,5ml @100L, which is Alk-dose/4,6 or
Ca 9,2ml @100L -> +10 mg/l

b) Modified Alk recipe (avoiding over-saturation)
b1) 400g NaHCO3 (baking soda) mixed with RODI water up to a 5 liter stocksolution
- Alk: 37ml @100L -> 1,0 dKH
b2) CaCl2 2xH2O recipe as before
- Balanced Ca dosing: Alk-dose/5,7

c) Na2CO3 instead of NaHCO3
c1)500g Na2CO3(soda ash) mixed with RODI water up to a 5 liter stocksolution
- Saturation is ok (46%)
- Alk: 18,8ml @100L -> 1,0 dKH
c2)CaCl2 2xH2O recipe as before
- Balanced Ca dosing: Alk-dose/2,9

Hope that helped.
All calculations done with the flexible 2/3 part module of AquaCalculator (WindowsApp)

best rgds

07/31/2017, 04:05 AM
The brand is called Royal Nature (http://royalnature-reef.com/) And their website information is slightly different than the instructions taped to the lids of those canisters. But concentrations are the same.

Decided to go with the following diluted solutions, before mixing tho tell me if this is stupid:
First Alk, to avoid oversaturation,
800g of NaCHO3 to 10 liters of Ro/Di (first 8 then the powder and top up to 10l)

Then Calc, and to be in the ballpark of how relatively they are consumed, mixing 350g of CaCl2*2H2O (mixing the same way as NaHCO3 to 10l)

In no means am i trying to be precises on balanced addition of calcium and alkalinity in relation to each other, im only trying to tune in the dosing of the liquids so that the ammount of both calc and alkalinity would be dosed in close relation to eachother.

By the previous calculations this should be close:
- Alk: 37ml @100L -> 1,0 dKH
- Balanced dosing 1:1

My thinking behind this is that, this way
a) I top up and mix both solutions on most likely on the same day for my 10l jugs (top up jugs)
b) so i can monitor relatively closely on the consumption and addition of both elements in relation to each other
c) trying to maintain ionic balance as closely as possible with hobbygrade testing and addition of the elements.

Thank you for everyone commenting so far, this has cleared up alot of the questions i'v had so far.

07/31/2017, 05:04 PM
I think that the calcium solution should be a bit weak if mixed that way. What product are you using? Is it hydrated or anhydrous? What's the purity level?

07/31/2017, 05:04 PM
This article has formulas for the solutions: