Nutrient ‘additives’ supply substances that are “chemically” incompatible with concentrated nutrient formulations. For example, a meaningful amount of silica is unstable in concentrated nutrients and therefore must be stored in a separate container.
Additives are also necessary for supplying those substances which have a dose rate that varies throughout the growth cycle at a different rate than the base nutrient. This is often the case with plant growth regulators (PGR’s) or hormone additives.
- “PK” Flowering additives
- Silica additives
- Humic & Fulvic acids
- Nutrient disinfectants (Sterilizing agents)
- Plant growth regulators (PGR’S)
- Seaweed (kelp) additives
- Calcium, magnesium, iron additives
Common issues with additives
Although additives can provide lucrative yield benefits, they can cause negative side-effects:
- Chemical compatibility: Certain additives are unstable when mixed with nutrient solutions, or other additives. This problem is often encountered when employing certain organic compounds, especially those in powdered form. Such problems can usually be avoided by following a nutrient manufacturer’s recommended feed schedule.
- pH change: All additives will impose some change on the nutrient solution pH - some more than others. For example, alkaline conditions are needed to stabilize concentrated solutions of ‘silica’ and many ‘PK’ flowering additives. Hence, these additives can cause a significant pH increase when they are added to nutrient solutions. Therefore, as a rule, ensure to immediately check the nutrient’s pH after dosing with additives.
- Algae and slimes: Carbohydrate (or sugary) additives often induce the growth of algae and slimes in nutrient solutions. This can attract pests and cause blockage of plumbing (e.g. drippers, jets, feed lines).