Creating Stock Fert Solutions - Can Someone Check my Math?

DGalt

DGalt

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Jun 1, 2008
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Connecticut
I'm going to be purchasing dry ferts and putting together stock solutions to make my life easier. My goal here was to figure out how many drops of a specific solution I needed to add to my tank so that it equaled the dosing suggested by EI.

This is for my 15 gallon. I'm going off of these numbers:
10-20 Gallons
1/8 tsp KNO3 3x a week
1/32 tsp KH2PO4 3x a week
1/32 tsp CSM + B Plantex for traces 3x a week

I'm using the conversion of 1 drop = 0.05ml.

So, for KNO3:
1 tsp = 5.6g
1/8 tsp = 0.7g
Therefore, if I were to make a 0.7g/mL solution (e.g. dissolve 350g in 500mL), I could put in 1 mL (i.e. 20 drops) of the solution for my 1/8tsp of KNO3.
Since 20 drops requires more effort than I want (:silly:), I'm planning on making a 1.4g/mL solution and only putting in 0.5mL (10 drops, much easier than 20 :lol:)

For KH2PO4:
1 tsp = 4.8g
1/32 tsp = 0.15g
Using the same logic as above:
0.15g/mL solution (then add 20 drops)
instead, 0.30g/mL solution (add 10 drops)

I can't find a tsp to grams conversion for CSM + B Plantex. Does anyone know what it would be (roughly)?
If not, I'll just weigh 1 tbs when I get the stuff and figure it out from there (I much prefer using weight rather than volume measurements, if you haven't noticed lol)

Let me know if I made a mistake here. Thanks :)
 
I'm a rather broke college student. 1lb of ferts for $3 beats $20 or whatever it is for a bottle of Seachem :thm:

I have access to balances and dH2O as well, so that makes the process easier.
 
i'm too lazy to do your math but i dont think you can do it. you can't get a bunch of ferts to dissolve in that much water. if you use gadds downloadable calculator it will tell you if you can't put that much in. here is his site. http://www.csd.net/~cgadd/aqua/articles.htm

i wanted to do the same thing but it won't work. i used the most amount of K that the calculator recommeded and it still isn't completely dissolved. i have to shake the solution everytime i want to use it
 
I didn't even think of solubility issues. bah! I suppose if solubility is an issue you can dilute it until it dissolves and then figure out how many mL to add.

I don't understand that calculator, at least not in terms of what I'm trying to do. For example, EI says to put 1/8 tsp of KNO3 in 3x a week. But according to the calculator, 1/8 tsp in 1 mL (so that you aren't diluting it) in a 15gallon tank will supposedly cause 7.56 ppm Nitrate. Dosing that 3x a week seems rather high.

Am I not understanding something here?

Edit:

So I found a solubility chart over at APC. (here)

Apparently KNO3 won't dissolve past 0.357 g/mL, which is kind of obnoxious since that translates into 2mL or 40 drops.

KH2PO4 is a little bit better since I can do 0.15g/mL (its coefficient is 0.22g/mL)

starting to think that just tossing dry ferts in the tank will be easier :/
 
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I go by this chart and I have no problems at all.

DosingCharts.jpg


I hope this helps.
 
I haven't bothered with mixing my dry ferts into solutions yet. I got one of those weekly pill container things (1 compartment for each day of the week) and measured out the amount of ferts for each dose. Since I dose every other day it lasts 2 weeks. Measuring out 2 weeks worth at once is a lot easier.
 
I do dry if it's above 20 Gal or so.
Some prefer liquids.

Whatever gets the job done and is something you and your habits will adhere too is the main thing.

I dislike liquids and transferring them, dribbling everywhere etc, pump dispensers help there a lot, and self fill bottles etc are worth their weight.
Nice little racks to hold the liquids also help and placed next to the fish food, helps to remind.

Still, I find it much easier to toss some dry ferts in and I still dissolve the traces into water etc, then dose that.

For macros, you need not fret over the a ppm here or there.
That will never make or break a tank.

CO2 will rather easily if not attended to.
Focus there.

Regards,
Tom Barr
 
i might have messed up with my math but i think that caclulator isn't correct anyway. i'm not a mathmetician (or very good at spelling) but i think i've found some errors.
 
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