Untreated Water Is High Risk

Untreated water such as River water is host to a wide range of root disease-causing organisms in hydroponics. Pythium is one of the main ones. Pythium comes from the soil and is carried into the river on dust or silt. Pythium loading in the water supply will fluctuate and will increase after storms or rainfall when more soil and contaminated debris is washed into the river.

When Pythium is carried into the sterile environment of a hydroponic system via untreated water it can quickly colonise the growing media and infect the root system. Pythium-infected plants will show an overall decline in yield as nutrient and water uptake is reduced due to the infected and stressed root system.

It will then increase in severity. Plants will then begin wilting as the roots are no longer able to sustain the growth and water demand of the plants.

The only way to treat this problem is to fully sanitise the water source (eliminate the source of the disease) and strengthen the immune system of the crop.

It then becomes a waiting game where new, healthy, live roots must outnumber the dead or dying ones.

If the water source remains untreated the plant will be unable to regenerate a healthy root system and the crop will be lost, or yields will be substantially reduced.

This is a common problem for hydroponic growers and is particularly devastating for longer-term crops.

A lot of investment goes into growing the plants to a certain stage and then the projected yields are lost or significantly reduced when root disease infection is unable to be controlled.

All inputs of the growing system must be sterile:

Growing media, nutrients and water supply.

If Pythium infection occurs it then becomes a process of elimination to identify how the Pythium entered the system.

An untreated (not sanitised) water supply will be the obvious and inevitable source of infection.

For our clients, we recommend using Oxine.

This is a patented slow-release Chlorine Dioxide solution.    

Growers fill their holding tanks with untreated water (e.g. river water), measure out the required amount of Oxine for treating that volume of water e.g.  2 litres of Oxine to treat 20,000 litres of water to be treated.

Then the 2 litres of Oxine is activated with 200 grams of citric acid crystals. The solution then sits for 10 minutes to activate fully and is then dripped in to the 20,000 litre storage tank and agitated with a pump or air pump to mix it in.

After 12 hours of contact time (i.e. sitting overnight) the 20,000 litres is then fully sanitised and ready for use in the hydroponic tank.

A second tank should be used for untreated water and one tank for treated water. That way the treated water never becomes contaminated with untreated water and you always have a high volume of water on site awaiting treatment.

A 20 Litre container of Oxine costs NZ$415.00 + GST and requires 2kg of Citric Acid crystals for activation for NZ$35.00 + GST

20 Litres is enough to fully sanitise 200,000 litres of river water.

Because the product is a liquid sanitiser there is no capital outlay or expensive equipment required that requires maintenance. It can be implemented at short notice and easily deleted from a grower’s product range if they decide to move to another method of treatment later.

The Oxine is an easy to use and highly effective way of sanitising water supplies and has a number of other uses within the growing operation as detailed in the link below.  

We would highly recommend it for any grower that is using untreated water supplies as in those situations Pythium infection will be inevitable.