[rjordan393]

Hello All,
            I wonder if there are chemist's on this board that are also fresh water fish keepers with plants. If there is; I would like to know if mixing the following chemicals all together either dry or in solution can be accomplished safely and if there are pro's or con's to doing this. Can anything happen short or long term?
Those who keep plants in their aquariums have been either dosing dry fertilizers or making up their own stock solutions in separate containers for each fertilizer.
The fertilizers are: KNO3, KH2PO4 & K2SO4.
Also will calcium sulfate & magnesium sulfate (used for general hardness) have some effect on above fertilizers either mixed dry or in solution with them?
 
To help you determine if this can be done, I submit the following as an example:
75.2 grams of KNO3 to 500 ml distilled water. 30 ml dose of this to 64.9 gallons of aquarium water results in 11.3 NO3 ppm added.
11.5 grams of KH2PO4 to 500 ml distilled water. 30 ml dose of this to 64.9 gallons of aquarium water results in 1.96 ppm PO4 added.
45.7 grams of K2SO4 to 500 ml distilled water. 45 ml dose of this to 64.9 gallons of aquarium water results in 7.51 ppm K added.
So can these chemicals be mixed together either dry or in solution and still give the same results?

There is an online calculator http://calc.petalphile.com/ that plant keepers use to determine weight of the chemical for a stock solution holding a certain volume, to dose how many milliliters to a certain volume of aquarium water that results in a certain part per million.
A lot of fish keepers with plants would like to know.

I just noticed a fellow fish keeper placed a similar question in this topic.
Moderator feel free to delete my post if its necessary.

[Arkcon]

Yes, you can mix those major salts together.  Can you see why?  What reaction can you expect to happen -- did you notice the cation is the same in each case -- potassium?

[rjordan393]

Ok,
     That answers part of my questions but If I were to combine all three bottles contain 500 ml of stock solutions to a 1500 ml bottle, How would I know how much to dose in order to get the same results in ppm from each individual chemical as listed above. I suspect there would be a problem either with the strength of the three solutions when combined and/or their volumes.

[Borek]

How would I know how much to dose in order to get the same results in ppm from each individual chemical as listed above.

http://www.chembuddy.com/?left=concentration&right=dilution-mixing

[rjordan393]

Thank You.

[DLoja]

75.2 grams of KNO3 to 500 ml distilled water. 30 ml dose of this to 64.9 gallons of aquarium water results in 11.3 NO3 ppm added.
11.5 grams of KH2PO4 to 500 ml distilled water. 30 ml dose of this to 64.9 gallons of aquarium water results in 1.96 ppm PO4 added.
45.7 grams of K2SO4 to 500 ml distilled water. 45 ml dose of this to 64.9 gallons of aquarium water results in 7.51 ppm K added.
So can these chemicals be mixed together either dry or in solution and still give the same results?

All you need to do first is get your doses to be the same.  Since your KNO3 and KH2PO4 doses are already that same at 30 ml, lets just adjust your dose of K2SO4 to 30 ml as well.

Right now you are dosing 45 ml of your 500 ml total, or exactly 9% (45/500).  9% of your 45.7 g means your ideal dose is 4.113 g of K2SO4 each time.  Since we want to get that dose to 30 ml, or exactly 6% (30/500), you will have to increase the amount of K2SO4 added to your 500 ml total by 50% or in other words, add 68.55 g, which when dosing 30 ml or 6% gives you the same desired 4.113 g per dose.

Now that you've adjusted your K2SO4, just pour them all together.  The key is that to keep dosing 30 ml you'll have to fit it all in the same 500 ml of water.  If that's not enough water to dissolve it all, then trying dosing 60 ml of a total 1000 ml solution, or 90 ml of a 1500 solution.  You're only changing the amount of total water to dissolve the same amount of ingredients into while keeping your dosing % the same (6% in this case).  Make sense?

Good Luck,
David

[rjordan393]

It certainly does. I sent a reply on the Barr Report forum.