# Problems with dry ferts



## TorontoPlantMan (Aug 16, 2013)

Hey guys,

I'm having issues getting these ferts to calculate properly based on this calculator: http://rota.la

Lets take a 40 gallon aquarium as an example and compute the following

KNO3- 500ML - 10ML dose = 92.58 grams
KH2PO4 - 500ML - 10ML dose = 14.10 grams
now here is where the problem starts
K2SO4 - 500ML - 10ML dose = 126.53 grams HOWEVER I get an error with this one unless I change the dose to 30ML which screws up the KNO3 and KH2PO4, I always get this message "The solubility of K2SO4 at room temperature is 120 mg/mL. You should adjust your dose."

Anyone have any advice as per how I can get the K2SO4 to dissolve properly?


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## arturo (Jun 29, 2014)

why do you think its screwed up? Are you combining the dry salts in one bottle? The calculator is giving you the recommended dose to hit the target. If it takes a 30ml dose to reach solubility, why not just dose 30ml and keep each solution separate? 

Are you auto dosing? Are you calculating for EI?


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## TorontoPlantMan (Aug 16, 2013)

arturo said:


> why do you think its screwed up? Are you combining the dry salts in one bottle? The calculator is giving you the recommended dose to hit the target. If it takes a 30ml dose to reach solubility, why not just dose 30ml and keep each solution separate?
> 
> Are you auto dosing? Are you calculating for EI?


You cannot calculate one ingredient at 10ML dose and then change the other to 30ML dose, these substances are meant to be mixed into one bottle and dosed together.

Individual bottles of each one is a bit unnecessary since they can be mixed, just trying to figuring out how to do it properly as I normally do not add KS2O4.


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## arturo (Jun 29, 2014)

TorontoPlantMan said:


> You cannot calculate one ingredient at 10ML dose and then change the other to 30ML dose, these substances are meant to be mixed into one bottle and dosed together.
> 
> Individual bottles of each one is a bit unnecessary since they can be mixed, just trying to figuring out how to do it properly as I normally do not add KS2O4.


oh, i got ya. See, i usually just dry dose but I'm thinking of moving to a solution.

It might be as simple as just changing your dose to 30ml across the board?


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## TorontoPlantMan (Aug 16, 2013)

arturo said:


> oh, i got ya. See, i usually just dry dose but I'm thinking of moving to a solution.
> 
> It might be as simple as just changing your dose to 30ml across the board?


I have an auto dosing pump so dry dosing is not an option; if I change all the others to 30ML then they get diluted quite heavily and your solution will run out X3 as fast.

There has to be a real solution as many of the companies selling E.I ferts give instructions on how to mix the three together, and they generally have 5-10ML doses.


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## arturo (Jun 29, 2014)

maybe I'm overlooking something, but the issue here is that you're trying to dissolve too much of the K2S04 in too little water. could you not just grab some larger dosing bottles?


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## aniroc (Aug 23, 2012)

You cannot dissolve more than 120 grams of K2SO4 in 500 ml water since max solubility is 240grams/liter at 100 C (boiling water). 
You can make a separate solution, say 60 grams/500 ml (maximum solubility at 25C) and dose double.


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## hendy8888 (Sep 10, 2010)

aniroc said:


> You cannot dissolve more than 120 grams of K2SO4 in 500 ml water since max solubility is 240grams/liter at 100 C (boiling water).
> You can make a separate solution, say 60 grams/500 ml (maximum solubility at 25C) and dose double.


Agreed, if you get that warning on the fertilizer calculators you need to decrease your concentration of stock solution until it is able to be fully dissolved and compensate this with dosing larger amounts each time. It's an issue when dosing large tanks, not so much with small tanks.


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## Sameer (Sep 30, 2007)

Dunno if this helps, this is the question I asked for my 45 gal. I wanted to dose 20 ml.



> You want to use "The Estimative Index" selection for a tank with high light and CO2 injection. EI daily would be if you dosed every day instead of every other day.
> 
> 1,000ml bottle and 20ml dose
> KNO3 104.156g (20 tsp.)
> ...


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