Nutrient Solutions

Greenhouse and hydroponic
systems information



Simple Chemistry

Conductivity & pH

Laboratory Analysis

Crop & Season Effects

Recipe Calculations

Fertiliser Quality

Practical Tips

Day to Day

Solution Management


Most of the chemicals required for making nutrient solutions are also used by the fertiliser industry. Readily available fertiliser grade chemicals may be hard to dissolve, or may contain impurities which have either a nuisance value or may be harmful in nutrient solutions. Better grade products suitable for hydroponic use are sold as greenhouse grade or technical grade products. Major components of hydroponic solutions are generally available as listed below.

Calcium nitrate, greenhouse grade = , 15%N+20%Ca

Calcium chloride, technical grade = 27%Ca+48 % Cl

Potassium nitrate, greenhouse grade = 13%N,38%K -

Iron Chelate - many types of iron chelate are available at a wide range of prices. FeEDTA (Iron- ethylene diamine tetra acetic acid or sodium salt) is suitable (provided that it is a high quality product) and should contain 13% Fe. Some unbranded sources of FeEDTA are difficult to use.
FeDTPA ( Iron diethylene triamine penta acetic acid), usually 11%Fe but there are other grades. This chelate may be the better choice for nutrient solutions recirculating through media where the root zone pH may be above 6. The AKSO, Dissolvine, Librel and Sequestrene brands are widely sold internationally and are suitable.

Mono-ammonium phosphate - technical grade = 12%N+27%P

Mono-potassium phosphate- technical grade = 22%P,28%K

Phosphoric acid, 65% food grade = 220 g P /litre

Nitric acid (70%) technical grade = 440 g N/litre

Ammonium nitrate Fertiliser grade = 35% N (special rules apply to supply and use in Australia)

Potassium sulphate greenhouse grade or water soluble grade (fertiliser grade is very hard to dissolve) = 42%K+17%S

Potassium chloride - greenhouse or technical grade = 52%K + 48%Cl

Magnesium sulphate (Epsom Salts) - most grades are suitable = 10%Mg + 13%S

Magnesium nitrate - technical grade = 11%N +9.7%Mg

Manganese sulphate - technical grade Manganese sulphate tetrahydrate = 24.6%Mn

Zinc sulphate - technical grade Zinc Sulphate heptahydrate = = 22.7%Zn

Copper sulphate - technical grade Copper Sulphate pentahydrate = 25.5%Cu

Borax - technical grade sodium tetraborate decahydrate = 10.7%B

Boric acid - technical grade = 17.5%

Solubor and similar 20% boron products - technical grades

Sodium molybdate -technical grade = 39.6%Mo

Ammonium molybdate - technical grade = 54%Mo

Ready mixed trace elements are widely sold. but their use is not recommended, as the balance of the trace elements may or may not suit the water supply or the crop requirements. All trace elements are also available as chelates, they are expensive, and in our opinion, except for iron they are not necessary.

Some fertiliser brands which are sold internationally and which offer greenhouse and technical grade products suitable for making hydroponic solutions include Haifa Chemicals, Kemira, Yara ( Hydro-Agri Rotterdam). These fertilisers are reasonably safe to handle using common sense. Material Safety Data Sheets (MSDS) are not widely offered. Some of these manufacturers have web sites which may provide detailed product specifications and product MSDS.

Original 29/9/1999- revised 14/1/04/, 24/7/06 .

:R A J White 5/7/07