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Introduction Of (CaNO3)2 into Dosing Regime.

Quetzalcoatl

Quetzalcoatl

Member
Joined
12 Jul 2011
Messages
324
Location
South Cheshire
I have soft water in my area and as a consequence my GH is bearly measurable! I have purchased some (CaNO3)2 to try and allieviate the issue but I am unsure as to when, and how much to dose? Or even if it`s necessary for that matter?

I am using EI at present and dosing is as follows.
KN03 - 1/2 teaspoon
KH2PO4 - 1/8 teaspoon
MgSO4 - 1 tablespoon

Trace - 1/8 teaspoon
(Alternating days)

Will I need to reduce the ammount of KN03 now that I`m going to be using Calcium Nitrate. Will I get sufficient Nitrate from the (CaNO3)2 alone?

180ltr. Medium Planted. Pressurised Co2 (Lime Green DC). Light 7hr - 2.5wpg. EI

Thanks all. Help put my mind at ease please! :thumbup:
 
Hi all,
Nitrogen
You just need to do a little bit of maths, and slightly tweak the formula. Unless the calcium nitrate has been stored in a desiccator it will the tetrahydrate form, so the formula will be Ca(NO3)2.4H2O. This makes quite a difference to the amount of nitrogen. The RMM is 164.088 g/mol (anhydrous) & 236.15 g/mol (tetrahydrate).

You need the RAM of Nitrogen, which is 14, and we have 2 of them in (NO3)2, so that is 28. the percentage of nitrogen is then 28/236.15 = 12%, so there is only 12% N in calcium nitrate tetrahydrate.

You can do the same calculation for KNO3 - RMM = 101.1 so 101.1/14 about 14% N. You could if you wished work out how much more calcium nitrate tetrahydrate you would need to supply the same amount of N, by dividing 14 / 12 =1.17 and multiplying the KNO3 amount by 1.167. This will give you how much calcium nitrate you would need to add to add the same amount of N as your KNO3 addition.

Potassium
What you have to remember is that potassium nitrate is a more important source of potassium (39% K) than it is of nitrogen, so if you reduce the amount of KNO3 you add, and substitute Ca(NO3)2.4H2O you would need to add a potassium source, either as potassium chloride (KCl), potassium sulphate (K2SO4) or in your case probably best as potassium bicarbonate (KHCO3).

Personally I'd just add the calcium nitrate additionally to the potassium nitrate, unless you already have another potassium containing salt .

Personally I probably wouldn't have bought the calcium nitrate, if you add some "Oyster shell grit" (in a bag, to the filter) it will add both calcium and raise the carbonate hardness (dKH). "Oyster shell grit" is easily and cheaply available as chick grit for chickens.

Now you have the calcium nitrate I'd buy some potassium bicarbonate, and use that as my additional potassium source and to provide some carbonate hardness.

cheers Darrel
 
hi,

I have ultra soft water as well. What I do is:
use KNO3 as recomended and,
use a bit of CaCl2.2H20 which readily dilutes in the water. I just throw in half a teaspoon directly into the tank (10l tank) once a week. I do not if it's too much or not . I have not bothered doing the maths but all seems nice and easy.

hope this helps.

GM
 
Quetzalcoatl said:
...Will I need to reduce the ammount of KN03 now that I`m going to be using Calcium Nitrate.
Click to expand...
No, you don't need to do anything and you don't need to buy anything else unless you want to. Just add a couple teaspoons of the Calcium Nitrate to your mix and you will be fine. I always try to remind people that you are not to be concerned about GH just for GH's sake. Your plants need a bit of Magnesium and a bit of Calcium - and the combination of these two equal GH. So GH is a means to an end not an end in and of itself. As long as you have the presence of Calcium and Magnesium the plants will be fine.

Quetzalcoatl said:
Will I get sufficient Nitrate from the (CaNO3)2 alone?
Click to expand...
Well, No and Yes. The percentage of Nitrate in (CaNO3)2 is only about a quarter of what it is compared to KNO3 so that means you'd have to dose about 4X as much Calcium Nitrate to get the equivalent amount of Nitrate that can be found in Potassium Nitrate. This would be inefficient, plus you would still need to get enough Potassium, which the KH2PO4 cannot provide unless you add a boatload of it. So just use KNO3 to get enough Nitrate and use a little bit of the (CaNO3)2 to get enough Calcium in exactly the same way as you use MgSO4 to get a little bit of Magnesium. Everything else you can forget about, and this makes life very easy without the need to earn a Master's Degree in Chemistry.

Quetzalcoatl said:
Help put my mind at ease please! :thumbup:
Click to expand...
Here's how to be at ease: Never ignore nutrition in an enriched tank but don't over-think it either, otherwise you wind up outsmarting yourself. Remember N P K + traces. the best source of N and K is KNO3, best source of P is KH2PO4 - everything else is played by ear - MgSO4 for Mg and any soluble Calcium salt for Calcium. Any trace mix can be used for the rest.

Cheers,
 
As always a massive thanks guys! :thumbup:

@ Alastair. Can`t believe I missed that thread. I did a search prior to posting to see if there was anything of a similar nature, but must of missed it! It sounds like we have a similar issue then? Have you seen any benefit from adding the additional (CaNO3)2. Is that one tablespoon you are dosing for the 450ltr Vision? I presume you are adding your Macros on the same day?

@dw1305. I am a Design Engineer by trade, and I thought that I was quite a technically minded person? I have read your post several times, and it still fries my brain. Thanks for the chemistry lesson pal. 😀

I`m all for an easy life. Looks like I will be dosing the(CaNO3)2 in addition to the KNO3 just to keep things simples! Sorry, I forgot to mention that I am adding the salts straight to the tank. No mixing solutions. What would be a good starting measure for my 180ltr? Does it matter if I dose on Macro, or Micro day?
I brought a GH/KH test kit (Sorry ceg) just to confirm my suspisions of my low GH. What should I be aiming for in regards to degrees? At present I`m registering around 1dKH.

Thanks again.
 
Hiya, yes I add a generous spoon on the same day as my macro to my big tank. I noticed the tips of some of my plants dont look distorted anymore. I'd tried making sure it wasn't co2 related etc. I just add the teaspoon on water change day or the day after. I've never tested my waters hardness, intact I've never tested anything in their. I only decided to start looking into adding the calcium after I'd looked at my water boards figures. I have chocolate gouramis who love very soft and acidic waters, so don't want to put too much in. I also noticed my plants pearled quicker too. Whether this was just a coincidence I'm unsure. I just took clives advice and just started adding the spoonful and it's not had any bad impact on my soft water fish. I didn't even bother with the fact it may add a teeny bit more nitrate too as I saw it as more for the plants ha ha.
 
Quetzalcoatl said:
...I brought a GH/KH test kit (Sorry ceg) just to confirm my suspisions of my low GH...
Click to expand...
Pfah..Philistine! Do you realize how many bottles of Old Speckled Hen you could have had for the same price (clearance sale at Tesco)? Unbelievable... :evil: :thumbdown:
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Cheers,
 
Hi all,
I am a Design Engineer by trade, and I thought that I was quite a technically minded person? I have read your post several times, and it still fries my brain.....
Click to expand...
Get away with you, it really is quite straight forward.

You need a "Periodic Table of the Elements" - one from this page <http://www.dbooth.net/mhs/chem/periodictable.html> and the chemical formula of your compound (Just type the name into Wikipedia).

Then it is just a case of adding the RAM (Relative Atomic Mass) of the elements together to get the RMM (Relative Molecular Mass).

So for KNO3 - 1 x K (RAM = 39.1), 1 x N (RAM = 14) and 3 x O (3 x 16) > 39 + 14 + 48 = 101.1, this is the RMM of KNO3 (potassium nitrate).

The percentage of K is 39.1/101.1 (RAM/RMM) = 0.39 = 39%. N= 14% etc.

You can do this for any part of the formula, so the nitrate percentage of KNO3 is: NO3 = 14 + 48 = 62/101 = 62% NO3.

Calcium nitrate tetrahydrate is a longer formula, but exactly the same principle applies.
Ca(NO3)2.4H2O ~ Ca = 40.1 + ((14 + 48)x2) + (4 x (2+16) = 40.1 + 124 +72 = 236.1 The RMM of 236

N = 28/236 = 0.119 ~ N = 12% and NO3 = 124/236 = 0.525 = 53% NO3.

Hope that is a bit better as an explanation.

cheers Darrel
 
Thanks Darrel, all seems so much clearer today? Cheers! :thumbup:
I must confess though. Sunday, and Monday were spent suffering a horrendous 48hr hangover that was aquired due to my brothers return from Oz. Not much made sense yesterday to be honest?
Absolutley NO Old Speckled Hen was consumed! However, I have no doubt that said beverage will be forced upon me when I visit Grandad at Christmas. Mmmmm. Warm Old Speckled Hen. Can`t wait? :sick:
 
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