# [Wet Thumb Forum]-Macro Mix



## imported_Ghazanfar Ghori (Jan 31, 2003)

What's the ideal ratios of N P K for planted
aquaria? 10: 1 : 10?

I'd like to mix up a batch of 'MacroMix'
using KNO3, KH2PO4, K2SO4 and end up with
the correct ratios. How much of each should
I be using to end up with the ideal ratio?

-
Ghazanfar Ghori


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## imported_Ghazanfar Ghori (Jan 31, 2003)

What's the ideal ratios of N P K for planted
aquaria? 10: 1 : 10?

I'd like to mix up a batch of 'MacroMix'
using KNO3, KH2PO4, K2SO4 and end up with
the correct ratios. How much of each should
I be using to end up with the ideal ratio?

-
Ghazanfar Ghori


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## 2la (Feb 3, 2003)

No idea what the "ideal" ratio is--not even certain I believe there is one--but something to consider: If the size or density of the granules are significantly different from each other, be sure to shake up the mixture thoroughly before dipping into it. Otherwise one substance or the other will settle and you'll get a scoop of a lot of one thing and little or none of the other. Or you may try pulverizing the mixture with a mortar and pestle.

40-gallon heavily planted
15-gallon heavily planted
10-gallon Tanganyikan
7-gallon South American
In theory, there is no difference between theory and practice. But, in practice, there is.


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## imported_Ghazanfar Ghori (Jan 31, 2003)

Oh I was planning to dissolve it all and dose with the liquid.
I know the preferred ratio per plant under different conditions
is probably different but there should be some middle ground.

-
Ghazanfar Ghori


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## ekim (Jan 31, 2004)

My ideal ratio would be something like 7:1:5 (N,P,K).
Maybe my tanks are a little under stocked with fish though!

Here is a *link* to Plant Nutrition BY KAREN RANDALL, there is a list of Minerals and app. concentrations of the minerals found in the plants... (dry weight). Not sure if that helps out.

I know some chemicals will participate out of solution if mixed in high concentration,
(CaNO3 & K2SO4) The potassium will knock the Calcium out of solution.
I think KNO3 and K2SO4 will be fine not sure what will happen once you add the KH2PO4

Keep us posted!

Thanks,
Mike Morrissey

*My Digital Gallery*


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## Rex Grigg (Jan 22, 2004)

The drawback to this is that I have noticed that in my tanks the uptake of various macros is not consistent on a week to week basis. Some weeks I struggle to keep NO3 in the tank and other weeks it's hardly used at all. Same goes for PO4. Since I don't test for K I'm not sure if the same happens with K or not.










American by birth, Marine by the grace of God! This post spell checked with IESpell available at http://www.iespell.com

See my Profile for tank details.

See my planted tank FAQ at http://members.dsl-only.net/~rex/


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## Roger Miller (Jun 19, 2004)

10:1:10 sounds like a starting point. You will probably want to adjust the mix from there.

Mike's ratio of 7:1:5 is interesting as well. You could probably mix that with just KNO3 and KH2PO4.

Depending on your tap water chemistry there might be a couple other things you could add to your macro mix. Epson salt comes to mind. Calcium might be useful too, but the phosphate and the calcium will precipitate. It may take a while but eventually they will precipitate.


Roger Miller

"The indispensible first step to getting the things you want out of life is this: Decide what you want" -- Ben Stein


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## imported_Ghazanfar Ghori (Jan 31, 2003)

Ok, I asked Dr. Greg Morin:

"Although its different for every plant, 
and different in various conditions, what's
the average NPK ratio needed by aquatic plants?"

His reply:
"NPK: 12:1:6 is a good ballpark figure"


So, since we're talking NPK ratios....

NO3 has 22.6% N by mass
PO4 has 31.9% P by mass

Now I need to figure out how much of
KNO2, KH2PO4 and K2SO4(if needed) I need to
dissolve to get the 12:1:6 ratio. Help?

-
Ghazanfar Ghori


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## Sir Plants-a-lot (Feb 16, 2003)

I'm sorry to rain on your parade, but you won't be able to get the right ratios using the three chemicals you mentioned. Your N source (KNO3) is 13% N and 38%K, so your N:K ratio is already 1:3 and will only get worse when you add the potassium phosphate. If you want to drive up the N without affecting K, you would need to add something like ammonium nitrate or nitric acid. I'm not sure I'd want to put either in a fish tank, although at ppm levels nitric acid would probably be ok in a well-buffered tank. If you happen to have access to magnesium nitrate, that would conveniently boost the N and do away with the need for Epsom salts.

Regards,
Kevin


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## gpodio (Feb 4, 2004)

You can obviously get an idea for a starting point however there are so many things that will effect these concentrations in the tank that you will need to eventually figure out the ideal amount your tank needs. Fish food, fish load, tap water and plant uptake are among the variables that are unique to each tank and would effect the overall ratio.

The way I do it is test the water every day for a week and keep a log of the results and how much chemicals I added to bring the levels of back to where I want them. I then just take the average over the week and prepare a monthly mixture knowing both ratio and amount of liquid to add all I need to do is set the automatic liquid doser to dose the amount I need of the mix each day. I obviously bring levels back up manually following a water change but the rest of the week the doser takes care of adding both macros and micros. I still test the water every now and then for P and N to see if anything has changed. Following large prunings I usually half the daily dose for a couple of days. Every so often I need to make a change to the ratio or amount of mixture to administer each day but on average things remain pretty constant.

Regarding K, I don't have a test kit for it, I know how much is added from the KNO3 and trace mixes and all I do is subtract that from the amount of K2SO4 that I add. If I see pinholes I increase the amount of K in the mixture and following water changes, otherwise I usually eye-ball it to around double the amount of N added. The values I try to maintain are N:5 P:0.5 and K about double of N.

So the ratio I try to keep in the water is 20:1:10
But that's obviously the ratio I try to maintain in the tank, not the ratio of macros I use in the mix. I'd have to check my logs to see what the actual ratio of the mix is lately.

Hope that helps
Giancarlo Podio


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## 2la (Feb 3, 2003)

> quote:
> 
> Originally posted by Sir Plants-a-lot:
> I'm sorry to rain on your parade, but you won't be able to get the right ratios using the three chemicals you mentioned. Your N source (KNO3) is 13% N and 38%K, so your N:K ratio is already 1:3 and will only get worse when you add the potassium phosphate.


That can't be right, because I know when I dose my tank up with 10ppm of nitrate I'm not getting 30ppm of potassium. Remember that N as N is different than N as NO3, which is what commercial test kits measure, I believe (or vice versa). If you go to Chuck Gadd's calculator and plug in the numbers, you'll see that you get roughly 1.6ppm of nitrate (NO3) per 1ppm of K when adding potassium nitrate.

40-gallon heavily planted
15-gallon heavily planted
10-gallon Tanganyikan
7-gallon South American
In theory, there is no difference between theory and practice. But, in practice, there is.


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## Roger Miller (Jun 19, 2004)

2la,

It looks like the numbers that Ghazanfar got from Greg Morin were for N, not NO3. Similarly, probably for P, not for PO4.


Roger Miller

"The indispensible first step to getting the things you want out of life is this: Decide what you want" -- Ben Stein


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## 2la (Feb 3, 2003)

So what would the ratio be in more easily understood terms (i.e., what the test kits measure)? All this time when people spoke of ratios I assumed they were talking about N as nitrate and P as phosphate, since that is what the kits measure. Wonder how much damage I've done or money I've wasted...









40-gallon heavily planted
15-gallon heavily planted
10-gallon Tanganyikan
7-gallon South American
In theory, there is no difference between theory and practice. But, in practice, there is.


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## imported_Ghazanfar Ghori (Jan 31, 2003)

That's the thing! Need to figure out how
much NO3, PO4, K needs to be added to
get N P K ratio of 12 : 1 : 6

NOT as simple as 12 ppm NO3, 1 ppm PO4, 6 ppm K

-
Ghazanfar Ghori


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## Sir Plants-a-lot (Feb 16, 2003)

Just to make sure we're all trying to figure out the same thing, does your N value refer to NO3 or to N only? And the P means phosphate or P only? 

I had assumed from your earlier calculations converting NO3 into N that the 12:1:6 ratio was for the NPK elements themselves, not nitrate and phosphate, and that you wanted 12ppm of N for every ppm of P, not 12ppm of nitrate for every ppm of phosphate. Now I'm not so sure which you are after.

Regards,
Kevin


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## Roger Miller (Jun 19, 2004)

2la,

I think most aquarists do use NO3O4:K when they talk about these ratios. I think the fertilizer specs on commercial fertilizers are for N2O5:K2O. The element ratios N:K come up when people are basing things on compositional ratios like the Redfield ratio.



> quote:
> 
> Originally posted by Ghazanfar Ghori:
> That's the thing! Need to figure out how
> ...


If the NPK values are for weight of the elements, then based on the percentages you quoted earlier, the ratios for NO3O4:K would be
12/0.226:1/0.319:6 or 53:3:6. Roughly 18:1:2.

Umm... Are you sure about the units?

Roger Miller

"The indispensible first step to getting the things you want out of life is this: Decide what you want" -- Ben Stein


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## gpodio (Feb 4, 2004)

> quote:
> 
> Originally posted by Ghazanfar Ghori:
> That's the thing! Need to figure out how
> ...


Indeed, if you like I will let you know exactly what I add however it's not going to be the same as your tank. That's the part that differs in every tank. If you were starting with distilled water then it would be easy to calculate. If you keep a log of test results and amounts of ferts added each time it's actually quite easy to calculate the required amounts and ratios to keep the levels right.

Giancarlo Podio


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## MarcinB (Apr 16, 2004)

> quote:
> 
> Originally posted by Roger Miller:
> the ratios for NO3O4:K would be
> ...


I did a quick search in the net for the N ratio in aquatic plants. It varied from 8 to 11:1 (N). In case of NO3O4 the corresponding value is 11-15:1

150L (40G) planted tank
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