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Tropica TPN+ match using ammonium nitrate

JamesC

JamesC

Member
Joined
3 Jul 2007
Messages
1,213
Location
Bexley, Kent
Been playing with my calculator again and come up with an almost exact match for Tropica's TPN+. Rather than use potassium nitrate for a source of nitrogen I have used ammonium nitrate which is what I'm led to believe is what is in TPN+. Using ammonium nitrate seems to tie all the figures in really well compared to when potassium nitrate is used.
Here goes for my DIY TPN+.

19.2g Ammonium Nitrate
2.2g Potassium Phosphate (monobasic)
10g Potassium Sulphate
17g Magnesium Sulphate Heptahydrate (Epsom Salts)
5g Aqua Essentials Trace Elements Mix
0.5g E300 Ascorbic Acid
0.2g E202 Potassium Sorbate
500ml distilled water


Comparisson of %'s

TPN+
N 1.34%
P 0.10%
K 1.03%
Mg 0.39%
S 0.91%
B 0.004%
Cu 0.006%
Fe 0.07%
Mn 0.04%
Mo 0.002%
Zn 0.002%

DIY TPN+
N 1.34%
P 0.10%
K 1.03%
Mg 0.39%
S 0.82%
B 0.01%
Cu 0.002%
Fe 0.08%
Mn 0.02%
Mo 0.002%
Zn 0.01%

Tropica recommend to dose 5ml per 50 litres of tank water per week.
Following this each dose of DIY TPN+ will add:

0.86ppm NH4
3.0ppm NO3
0.31ppm PO4
1.0ppm K
0.39ppm Mg

Ascorbic acid and potassium sorbate are added to help prevent the iron chelator from degrading. More on my webpage - http://www.theplantedtank.co.uk/allinone.htm

Please remember that this is all posted for information only and if you wish to test it then I'd strongly advise that you do it on a fish free tank first. But saying that people dose TPN+ without any problems.

James
 
Rather than use Potassium Sulphate for Potassium this formulation uses Potassium Nitrate which has the effect of lowering the Ammonium Nitrate amount.

14.4g Ammonium Nitrate
12g Potassium Nitrate
2.2g Potassium Phosphate (monobasic)
17g Magnesium Sulphate Heptahydrate (Epsom Salts)
5g Aqua Essentials Trace Elements Mix
0.5g E300 Ascorbic Acid
0.2g E202 Potassium Sorbate
500ml distilled water

Levels are as follows:

N 1.34%
P 0.10%
K 1.03%
Mg 0.39%
S 0.45%
B 0.01%
Cu 0.002%
Fe 0.08%
Mn 0.02%
Mo 0.002%
Zn 0.01%

Each dose now adds:

0.65ppm NH4
3.7ppm NO3
0.31ppm PO4
1.0ppm K
0.39ppm Mg

Not a great deal of difference, but a bit less Ammonium is now present. Exactly what Tropica use is very difficult to know so all I can do is work within their analysis.

James
 
Nice work mate!!!
 
Nice work there 🙂

I might give one of these a go as i need to order some trace mix.

What's the difference in behaviour between ammonia and ammonium? Is ammonium just as harmful? Will it still get converted into nitrates?
 
sounds good, I might give this a try 🙂 nice work James
 
JamesC said:
Here goes for my DIY TPN+.

3.8g Ammonium Nitrate
2.2g Potassium Phosphate (monobasic)
10g Potassium Sulphate
17g Magnesium Sulphate Heptahydrate (Epsom Salts)
5g Aqua Essentials Trace Elements Mix
0.5g E300 Ascorbic Acid
0.2g E202 Potassium Sorbate
500ml distilled water

Tropica recommend to dose 5ml per 50 litres of tank water per week.
Following this each dose of DIY TPN+ will add:

0.86ppm NH4
3.0ppm NO3
0.31ppm PO4
1.0ppm K
0.39ppm Mg
Click to expand...

Hey James, I must be doing something wrong in my calculations because I can't reproduce your numbers. An NH4 concentration of almost 1ppm sounds pretty high from a toxicity standpoint. Here's how I did my numbers (I did it the dunce cap way):

Molar mass of NH4NO3 = 80.04336 g/mol

Official percent composition by element
Element....Atomic Mass........Atoms.............Mass Percentage
.....H..........1.00794..............4...................5.037%
.....N..........14.0067..............2.................34.998%
.....O..........15.9994..............3.................59.965%

Atomic weight of NH4 is 14.0067 + 4*(1.00794) = 18.0347
The mass percentage of NH4 in NH4NO3 is therefore 18.0347 / 80.04336 = 22.53%

I reckon this means that 3.8 grams of NH4NO3 has 3.8*(0.2253)= 0.8563 g (856.3 mg) of NH4.

So 856.3 mg NH4 dissolved in 0.5 kg of water yields a solution with a concentration of 856.2 / 0.5 = 1712.37mg/L (ppm) NH4.

1 ml of this solution has about 1.7 mg NH4, so 1 ml of solution placed in 10 liters of tank water will yield a tank concentration of 1.7mg / 10kg = 0.17ppm.

This is about a quarter of what you list for the NH4 concentration.

From a toxicology standpoint I can only quote from the 1985 EPA studies which give the following data regarding ammonia toxicity tests:

The term ammonia refers to two chemical species of ammonia which are in equilibrium in water (NH3, un-ionized and NH4+, ionized). Tests for ammonia usually measure total ammonia (NH3 plus NH4+). The toxicity to ammonia is primarily attributable to the un-ionized form (NH3), as opposed to the ionized form (NH4+). In general, more NH3 and greater toxicity exists at higher pH. However, less NH3 is needed at lower pH to produce its toxic effects.
For a given pH and temperature, the percent of NH3 can be determined. Percent NH3 increases with temperature and pH. Some relevant numbers for most freshwater aquarium fish are presented in Table 1.


Table 1. Un-ionized NH3 as a percent of total ammonia (by temperature and pH).
..................................Percent NH3 of total ammonia
....Temp (F).................... pH

............... 6.5.........7.0.........7.5...... 8.0..........8.5
.....68....... 0.13...... 0.40 .......1.24......8.82........11.2

.....77....... 0.18...... 0.57 .......1.77......5.38........15.3

.....82....... 0.22...... 0 .70 .......2.17......6.56........18.2

.....86....... 0.26...... 0.80 .......2.48......7.46........20.3

The second table shows lethality of ammonia concentration as a function of temperature and pH.

Table 2. Lethal ammonia concentrations at 86 degrees F. (by pH, and duration of exposure)

pH......duration.......Lethal Ammonia Concentration (mg/l)
.................................total NH3

6.5.......1-hr..............14.3.....0.036
...........4-day.............0.73....0.002


7.0.......1-hr..............11.6.....0.093
...........4-day.............0.74....0.006

7.5.......1-hr..............7.3.....0.181
...........4-day.............0.74....0.019

8.0.......1-hr..............3.5.....0.26
...........4-day.............0.47....0.035

8.5.......1-hr..............1.3 .....0.26
...........4-day.............0.17....0.035

These were the LC50 values (Lethal Concentration for 50% of test subjects) so this means that at a pH of 6.5 at a total ammonia concentration of 14.3 ppm (of which there was 0.036 ppm of NH3) death occurred to 50% of the fish within 1 hour. At a total concentration of 0.73 ppm it took 4 days to kill half the fish.

If my computations of NH4 concentrations by dissolving 3.8 grams ammonium nitrate in a half liter of water are correct then the total concentration will be 0.17ppm. Using table 1 that means that under our typical CO2 injected tank conditions, a pH 6.5 and temperature of 82 deg.F seems reasonable therefore the percent NH3 due to the dosing alone should be approximately (0.0022)*1.7ppm = 0.0004ppm which is 5X lower than the 4 day LC50 value at pH 6.5.

If your computations are correct (0.86ppm) then under these conditions the NH3 level is less than 0.0019ppm which is very close to the LC50 4 day limit.

The EPA recommends that short-term concentrations of total ammonia should not exceed 0.1 ppm and longer term (4-day average) concentrations should be less than 0.02 ppm.

What amazes me is that you worry so much about approaching 100ppm NO3 concentration limits for fish in the aquarium yet you seem happy to dose NH4 which is quite obviously 5000X more toxic than NO3 could ever dream of being. :shock:

Cheers,
 
Yep, thanks Clive, something is wrong somewhere. I'll check it properly this time and update when done.

James
 
I know that the primary goal here is to reproduce TPN+ exactly, but here's the question:

Why would someone dose ammonium nitrate on purpose when one can dose potassium nitrate? Isn't reducing ammonium levels in the tank the whole point in fighting algae? In what way is dosing NH4NO3 better for plant growth than KNO3?
 
keymaker said:
Why would someone dose ammonium nitrate on purpose when one can dose potassium nitrate? Isn't reducing ammonium levels in the tank the whole point in fighting algae? In what way is dosing NH4NO3 better for plant growth than KNO3?
Click to expand...
This is exactly what I want to know. There must be something to it if Tropica use ammonium nitrate, ADA use either ammonium nitrate or ammonium chloride and Seachem use a compound very similar to urea called guanidine. Why don't all the people who dose these get algae? I dosed urea for a while and didn't get any algae growth.

I believe ammonia is easier for plants to utilise compared to nitrate.

There's a whole thread on this subject here - http://www.ukaps.org/forum/viewtopic.php?f=11&t=925

James
 
OK, figures now seem to be correct. Error occured when I back calculated to get the weight of ammonium nitrate. So now the actual weight of ammonium nitrate is a lot higher. The second formula I've done has reduced ammonium nitrate as some of it has been replaced by potassium nitrate. This is the max amount of potassium nitrate that can be used to keep within Tropica's potassium figure.

Must admit ammonium levels are higher than what I'd imagine they would be. Figures that are often quoted on forums suggest that 0.5ppm ammonia added daily is within safe levels and levels of 1ppm is the maximum. So looking at Tropica's figures which are weekly then they don't look so bad.

I'm not suggesting anyone go out and try this. It's posted for info and to try and find out why manufacturers make their products this way.

James
 
Hi Guys,good work and all that but i think i will just buy a bottle TPN + :lol: :lol: regards john ps (that ceg geezer is some sort of einstein :lol: )
 
James, I checked your values with my Excel Calculator (you can download the modified calculator from here).
I used the molecular weights from this site. I compared some of the results from this site with your molecular weight data and they match.

It looks like I get different results with the K and N percentages in the mix, while the P matches your results.

DIY TPN+ (1):
screencapture6eo7.png


DIY TPN+ (2):
screencapture5ee2.png


Am I doing anything wrong here?
 
OH, I just realized that I was looking at the fert quantities posted on your site, theplantedtank.co.uk which show different dosage values than the ones posted here (same results though).

With the data you posted here on this forum earlier, I can in fact verify that your first calculation (the one here without the KNO3) is right. 😳

The other one with the KNO3 dosage is still giving me 1,95% K instead of 1,03%.
 
keymaker said:
The other one with the KNO3 dosage is still giving me 1,95% K instead of 1,03%.
Click to expand...
It's because you are still adding the 0.9ppm that comes from the potassium sulphate that should have been removed.

Thanks for doing the checks for me. Took me quite a while to do by hand.
James
 
Yes, sorry, I just hadn't got round to correcting them yet as I made an error in those figures. Should be right now.

James
 
Not to put a spanner in the works but are we challenging the 'current belief' that ammonia triggers algae?

If so an the point you make is that the main 'knowledgeable' fert suppliers use ammonia can we not already assume that this 'belief' is in someway false??

Going to Diana Walstad's theories then maybe she is right? Maybe we can use ammonia as the N source rather than pay exorbitant amounts (although in our quantities is relatively small cost)????

AC
 
SuperColey1 said:
Not to put a spanner in the works but are we challenging the 'current belief' that ammonia triggers algae?

If so an the point you make is that the main 'knowledgeable' fert suppliers use ammonia can we not already assume that this 'belief' is in someway false??
Click to expand...

A couple of very fine questions. 'Ammonia in the presence of light causes Algae' isn't really a theory. The problem is, what do you replace it with? Several pages worth of hand-wringing, which won't be accurate either, and most people will fall asleep half-way through.
 
Just wondering, does anyone know of a source of ammonium nitrate that sells small quantities, ie 500g ?
Does it have an alternative name?
 
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