I've found a supplier here in the UK who sell KNO3, KH2PO4, K2SO4, MgSO4, K2CO3, CaSO4 and FeSO4.

Here is what say claim about each of these:

Potassium Nitrate

Potassium Nitrate (KNO3) contains 13.9% nitrogen (N) and 38.7% potassium (K)

Both nitrogen and potassium are macronutrients – essential for healthy plant growth.

Potassium nitrate can be added directly to a planted aquarium, or it can be mixed with water (preferably RO or DI) to make a stock solution. It can be mixed with other nutrients to make a bespoke fertilizer

If using the EI dosing system, typical maximum weekly uptake figures might be:-

Nitrogen (N) 4.5ppm. Potassium (K) 30ppm

Dry dosing

Adding potassium nitrate at the rate of 0.011 grams per litre to a tank will increase the nitrogen (N) level by

1.5 ppm and the potassium (K) level by 4.3ppm.

Added 3 times per week levels will increase by:-

Nitrogen (N) 4.5ppm.

Potassium (K) 13ppm.

Stock solution

Adding 61g of potassium nitrate to 0.5 ltr of water will give a stock solution with the following analysis:-

1.5% N (6.7% NO3) W/W

5.0% K2O (4.2% K) W/W

Added to the tank at the rate of 1ml / 10 ltr 3 x week will add 4.5ppm N and 13 ppm K

Monopotassium Phosphate

Monopotassium phosphate (KH2PO4) contains 22.8% phosphorous (P) and 28.7% potassium (K)

Both phosphorous and potassium are macronutrients.

Monopotassium phosphate can be added directly to a planted aquarium but as phosphates are normally required in very small quantities it is easier to mix it with water (preferably RO or DI) to make a stock solution.

It can also be blended with other nutrients to make a bespoke fertilizer.

If using the EI dosing system typical Maximum weekly uptake figures might be:-

Phosphorous (P) 1ppm. Potassium (K) 30ppm

Dry dosing

Adding Monopotassium phosphate at the rate of 0.0015grms per litre to a tank will increase the phosphorous (P) level by 0.34ppm and the potassium (K) level by 0.43ppm.

Added 3 times per week levels will increase by:-

Phosphorous (P) 1 ppm

Potassium (K) 1.3 ppm

Stock solution

Adding 15g of Monopotassium phosphate to 1 ltr of water will give a stock solution with the following analysis:-

0.77% P2O5 (0.34%P, 1.03% PO4) W/W

0.51% K2O (0.42% K) W/W

Added to the tank at the rate of 1ml / 10 ltr 3 x week will add 1ppm P and 1.3 ppm K.

Potassium Sulphate

Potassium sulphate (K2SO4) contains 44.9% potassium (K)

Potassium is a macronutrient – essential for healthy plant growth

Potassium sulphate can be added directly to a planted aquarium, or it can be mixed with water (preferably RO or DI) to make a stock solution. It can also be mixed with other nutrients to make a bespoke fertilizer

If using the EI dosing system typical Maximum weekly uptake figures might be:-

Potassium (K) 30ppm

Note! 13 ppm may have been provided from potassium nitrate and 1.3 ppm from potassium phosphate so only an additional 15 ppm is required.

Dry dosing

Adding potassium sulphate at the rate of 0.011grms per litre to a tank will increase the potassium (K) level by 5ppm.

Added 3 times per week levels will increase by:-

Potassium (K) 15 ppm

Stock solution

Adding 9g of potassium sulphate to 1 ltr of water will give a stock solution with the following analysis:-

0.48% K2O (0.4% K) W/W

0.16% S

Added to the tank at the rate of 1ml / 10 ltr 3 x week will add 15ppm.

Magnesium Sulphate

Magnesium sulphate (MgSO4) is used to provide magnesium an essential macronutrient.

Magnesium sulphate contains 9.86% magnesium (Mg)

Magnesium sulphate can be added directly to a planted aquarium, or it can be mixed with water (preferably RO or DI) to make a stock solution. It can also be mixed with other nutrients to make a bespoke fertilizer

If using the EI dosing system typical Maximum weekly uptake figures might be:-

Magnesium (Mg) 10ppm

Dry dosing

Adding magnesium sulphate at the rate of 0.05g per litre to a tank will increase the magnesium (Mg) level by 5ppm.

Added twice weekly, levels will increase by:-

Magnesium (Mg) 10ppm

Stock solution

Adding 56g of magnesium sulphate to 500ml of water will give a stock solution with the following analysis:-

1.0% Mg W/W

1.31% S W/W

Added to the tank at the rate of 1ml / 10 ltr 3 x week will add 3ppm.

Potassium Carbonate

Potassium Carbonate (K2CO3) contains 56.58% potassium (K)

Potassium carbonate can be added directly to a planted aquarium, or it can be mixed with water (preferably RO or DI) to make a stock solution. It can be mixed with other nutrients to make a bespoke fertilizer

If using the EI dosing system, typical maximum weekly uptake figures might be:-

Potassium (K) 30ppm

Dry dosing

Adding potassium carbonate at the rate of 0.011 grams per litre to a tank will increase the potassium (K) level by 6 ppm.

Added 3 times per week levels will increase by:-

Potassium (K) 18ppm.

Stock solution

Adding 80g of potassium carbonate to 1 ltr of water will give a stock solution with the following analysis:-

5.0% K2O (4.2% K) W/W

Added to the tank at the rate of 1ml / 10 ltr 3 x week will add 13 ppm K.

Calcium Sulphate

Calcium sulphate (CaSO4) contains 23.3% calcium (Ca)

Dry dosing

Adding calcium sulphate at the rate of 0.043g per litre to a tank will increase the calcium (Ca) level by 10ppm.

Stock solution

Adding 83g of calcium sulphate to 500ml of water will give a stock solution with the following analysis:-

3.3% Ca W/W

2.7% S W/W

Iron Sulphate

Iron sulphate (FeSO4) contains 20% Iron (Fe) which is a micronutrient.

In a planted aquarium, the target level for this element might be 0.1 ppm.

As this is small amount it is best added from a stock solution:-

Stock solution

Adding 5g of ferrous sulphate to 1 ltr of water will give a stock solution with the following analysis:-

0.1% Fe W/W

0.06% S W/W

Added to the tank at the rate of 1ml / 10 ltr will increase the iron content by 0.1ppm

Is it necessary to dose with all of these and is this the proper form of Fe to use?

Many Thanks

Bill