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Help with the maths for a newbie?

Phill Joynes

Seedling
Joined
23 Jul 2013
Messages
5
Location
Witney, Oxfordshire, UK
Please could someone help me do the maths here. This is what I have so far, but have checked using different calculators and have different figures every time, sometimes way out. My aquarium is 23 litres. I am just trying to work out the Macro solution, as I will be dosing Seachem Flourish (until it runs out) for trace.

I am trying to achieve the following a solution that is dosing 3 x 5ml weekly (nice and easy to do for my small aquarium).

So here are my maths:

Based on the dosing article on this site a 20 Gallon (assume imperial measurement) should be making the solution:

[3/16 tsp KNO3]*12 = 2 ¼ tsp KNO3
[1/16 tsp KH2PO4]*12 = ¾ tsp KH2PO4
[1/2 tsp MgSO4]*12 = 6 tsp MgSO4
Add these to 600ml of tap or distilled water
This mixture must serve 12 doses so each dose is 600ml/12 = 50ml

Therefore I believe my 23 litre, which equates to 5.05929 gallons (lets call that 5 Gallons, makes it a lot easier) so the calculations would be a quarter of the mixture:

[3/64 tsp KNO3]*12 = 9/16 tsp KNO3
[1/64 tsp KH2PO4]*12 = 3/16 tsp KH2PO4
[1/8 tsp MgSO4]*12 = 1 1/2 tsp MgSO4
Add these to 600ml of tap or distilled water
This mixture must serve 12 doses so each dose is 600ml/12 = 50ml

This is very small quantities and 50ml is 10 times that of my biggest syringe, so I will now attempt to get the measure to 5 ml. To do this I will do two things, 1 half the amount of water mixed from 600ml to 300ml (I only have 500ml bottles anyway), so my dose will not be 25ml, so still 5 times bigger than I would like. Next I will increase the powers by 5 and this should allow me to dose 5ml once a week and give me 60 doses, 5 months.

[15/64 tsp KNO3]*5 = 1 11/64, lets call this 1 1/5 tsp KNO3
[5/64 tsp KH2PO4]*5 = 25/64, lets call this 2/5 tsp KH2PO4
[5/8 tsp MgSO4]*5 = 1 7/8, lets call this 2 tsp MgSO4
Add these to 300ml of tap or distilled water
This mixture must serve 12 doses so each dose is 300ml/60 = 5ml

Is this correct? The site I visited suggested (based on the EI article on this site, with a link and approval):

Macro Solution
4tsp Potassium Nitrate
1tsp Potassium Phosphate
6tsp Magnesium Sulphate
500ml Water
Dosing
Macro 3x a week. (10ml per 50ltr of Aquarium water)

So equivalent to the top mix would be:

Macro Solution
2tsp Potassium Nitrate
1/2tsp Potassium Phosphate
3tsp Magnesium Sulphate
250ml Water
Dosing
Macro 3x a week. (5ml about 25litre, roughly my aquarium size)

This is why I am confused and probably over analysing it! If someone could help we out with the maths that would be great! I am aiming at ultimately using this a base line and then amending it if needed (if I have a deficiency and I my try and wind it down one by one slowly). So if I could make 5ml (any whole number between 1 and 5ml would be fine) doses that will last for about 3 months that would be great (I only have a 500ml bottle, so no more mix than that please)?

My water supply has a hardness of this:

Total hardness (various measurements) Fluoride
mgl CaCO3 (ppm) Degrees Clarke Degrees German(DH) Degrees French Detergent rating Fluoride(ppm)
253 17.71 14.168 25.3 HARD 0.123375

Should I still does the Magnesium Sulphate or not?

Also I noticed that in the article trace is only dosed 2 a week, is this correct or should it be 3 times, like Macro?

Thanks for even looking at this long post.
 
I think I am doing to much reading now :banghead: , I think I will mix 16.8g KN03 and 2.6g KH2P04 in 300ml of water and dose 5ml 3 times a week. I will not be dosing MGS04 as I think my GH is high enough.
Is this OK for my 23 litre tank (before I take the jump)? If not what would people suggest?

Now I am going to stop looking for answers everywhere on the internet as it is confusing me and I am sure I am just overcomplicating it! If it is not enough the plants will tell me and I will up the dose of the necessary item. Once they are happy then I can tweak to my specifics.
 
Well I'm certainly confused. Why are you limiting yourself to only using a 5ml syringe? Is it that tough to figure out how much water is 50ml? Just squeeze 10 syringe full in a cup or any vessel (like a test kit vial) and you'll immediately know how much 50 ml is. You really don't need to be accurate at all. These are just baseline numbers.

A water hardness value tells you nothing about magnesium content. GH = Calcium plus Magnesium so this could be any combination. You could have zero Mg plus 100% Calcium or, it could be comprised of 100% Mg and zero Calcium, or it can be comprised of any combination in between. The best policy is to add MgSo4 in the beginning then withdraw it to see if it makes a difference.

Cheers,
 
Thanks for the reply. Sorry, reading my post back I am confused to!

The only reason for trying to get a 5ml dose, is because I will keep the solution in a cupboard under the aquarium and it is easier to take one syringe full of solution than it is to do 10.

What I actually would like to know is, for my 23 litre aquarium, what should I set the baseline dose at? I have been reading to much from different sources and it is all confusing me (I think I have been doing to much research).
 
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