[APD] Re: Optimum nutrient levels

["Chuck H" <grendel at usit_net>]

Tom wrote:

> >Add the following back:
> 
> >1/4 teaspoon of KNO3
> >1/4 teaspoon of K2SO4
> >2 rice grain's worth, or around 200mgs of KH2PO4
> >5 mls of Trace( Tropica master grow, SeaChem Flourish etc)
> 
> >Repeat this except for the K2SO4 every 2-3  days.
> 
> >You also can mega dose right before the water change day.
> >You add 2-3x the amount of KNO3 and KH2PO4 24-12 hrs before you do a water
> >change.
> >The water changes removes the excess and the plants get very well fed.
> 
> >Just make sure your CO2 is 20-30ppm. 


And Steve asked:

> What would be the proper dose using Flourish Nitrogen, Flourish Potassium, Flourish Phosphorus ?


To figure this out, you first have to get an idea of how much stuff 
Tom's tsp recommendations are adding.  Chuck Gadd's calculator is 
very handy for this (note: when dry dosing, just enter a "1" in the 
"amount of water to mix with" box):

http://www.csd.net/~cgadd/aqua/art_plant_dosage_calc.htm


So, starting with KNO3, you can calculate that 1/4 tsp KNO3 yields 
approximately 11ppm NO3 and 7ppm K.

1/4 tsp K2SO4 yields approx. 9ppm K.

200mg KH2PO4 yields about 1.8ppm PO4 (the K here isn't enough to 
bother with).

Now we got some numbers to work with.  If you look at the label of 
the Flourish N & P products, you'll see a formula in the "advanced" 
part of the dosing instructions.

The formula for Flourish N is 0.05vn = m, where v = volume of tank in 
gallons, n = desired level of nitrate, and m = amount in ml of 
product to use (note that there is another formula listed, but it is 
for determining *nitrogen* dosing...we're after *nitrate* 
equivalency).

Just plug in 20 for the tank volume (v), and 11ppm for desired 
nitrate level (n):

	0.05*20*11 = 11ml

For Flourish P:

	0.8*20*1.8 = 28.8ml

Flourish K doesn't need a formula, since 1ml yields 1ppm K per 10 
gallons of tank volume.  So, if you add the 7ppm and 9ppm that Tom's 
dosage adds, you get 16ppm.  16*2 = 32ml.

So, to equal Tom's dosage, you need to add about:

	11ml Flourish N
	29ml Flourish P
	32ml Flourish K

Now, don't forget that a nominal tank volume (20gal in this case) is 
rarely if ever the actual volume of water held in the tank, and the 
example I laid out is just intended as an illustration.  I've found 
20gal tanks generally hold only 16-17gal once everything is said and 
done.  YMMV.  Anyway, Tom's recs are going to actually add more ppm 
of stuff to a tank than what I've shown, so adjust according to your 
own situation.  At the same time, don't drive yourself crazy trying 
to dial stuff in to the "T".  Close enough is good enough.

Hope it helps.
--
Chuck Huffine
Knoxville, Tennessee

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