All In One Solution

What is it?

After Tropica released their Plant Nutrition Plus, which is an 'All In One' dosing solution, I became interested in doing the same to make life easier for myself. Normally it is advised to keep potassium phosphate and iron traces in separate solutions to prevent any reaction occurring that results in an insoluble precipitate of iron phosphate. The chelated traces that are used contain iron that is complexed and as long as the iron remains complexed it should be safe from any reaction with the phosphate. The problem is that once the traces are in solution the chelator tends to deteriorate and so releasing the the iron. I discovered that the chelators used are a lot more stable in a solution with a pH of 6 or less. After a bit of experimenting I ended up using E300 Ascorbic Acid (Vitamin C) which not only keeps the solution acidic but is also an anti-oxidant. Enough is used so as to maintain a pH of 6. Another problem with keeping traces in solution is that they often tend to develop mould. To combat this I use E202 Potassium Sorbate which is a yeast and mould inhibitor. Luckily the Potassium Sorbate works most effectively at a pH around 6 which is what the solution is kept at.
It is advisable to keep the solution away from light as it can cause the chelator to break down.

How do I make it?

It depends on how you dose to what quantities of each chemical you add. The important thing to remember is that you must get the right amounts of the macro's and trace's mixed up especially if you currently dose different amounts of the solutions. Also it might be an idea not to make the solution too concentrated. What I do to make life easy is to adjust the levels so that one full fill (25ml) of my old Tropica bottle is enough to dose the whole of my 200 litre tank in one go.

As an example here is a formulation is based on my PMDD+PO4 formula:

10g  Potassium Nitrate
1.0g  Potassium Phosphate (monobasic)
4.0g  Potassium Sulphate
8.0g  Magnesium Sulphate Heptahydrate (Epsom Salts)
6g  Aqua Essentials Trace Elements Mix
0.5g  E300 Ascorbic Acid
0.2g  E202 Potassium Sorbate
500ml distilled water

If you wish to change the amounts of ingredients then as long as the levels aren't changed too much you can leave the amounts of Ascorbic Acid and Potassium Sorbate the same.

Dosing is 5ml per 40 litres
Each 5ml dose adds:
1.5 ppm Nitrate
0.15 ppm Phosphate
1.5 ppm Potassium
0.2 ppm Magnesium

DIY Tropica Plant Nutrition Plus

Tropica have very kindly provided an analysis of their product so with my calculator at the ready I have calculated a close match. Please remember that Tropica's TPN+ uses an ammonium compound for some of the Nitrogen content whereas I use all potassium nitrate.

48g 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

  TPN+ DIY TPN+
N 1.34% 1.34%
P 0.10% 0.10%
K 1.03% 3.8%
Mg 0.39% 0.34%
S 0.91% 0.62%
B 0.004% 0.01%
Cu 0.006% 0.002%
Fe 0.07% 0.08%
Mn 0.04% 0.02%
Mo 0.002% 0.002%
Zn 0.002% 0.01%

Tropica recommend to dose 5ml per 50 litres of tank water per week.
Following this each dose of DIY TPN+ will add:
5.9ppm NO3
0.31ppm PO4
3.8ppm K
0.34ppm Mg

Tropica's recommended levels I always find are a bit on the conservative side. They may be fine in a low light setup but with high light plus CO2 setups, higher levels of dosing are required. It is also better to dose through the week rather than one big dose each week. As a start I would recommend double dosing Tropica's recommended amount spreading the additions out over the week. I like to do a daily dose, but every other day should also be fine.
So for daily dosing you would need approx 1.5ml per 50 litres tank water.

Final thoughts

I have posted all of this mainly for information for others. I am by no means 100% certain if what I'm doing is correct or safe for fish and plants but so far all seems well. The additives I used are used commonly in the food and drinks industry so I'm presuming that they are safe.

So far the solution has remained clear and bright and has had no settling out for up to six months. Plants still grow and pearl as before.

In the UK you can buy the Ascorbic Acid and Potassium Sorbate quite cheaply from The Home Brew Shop and also sometimes on eBay.

This page was last updated 24th September 2008