Efficiently Disinfect and Clean your Hydroponic Systems with PHYSAN 20:

Physan 20 is the ideal candidate for cleaning out your hydroponic system. When diluted with water it is non-corrosive to all metals, and will not damage or mar natural rubber, glass, painted or plastic surfaces. Physan 20 can be applied for swabbing, irrigation cleaning, flushing, mopping and rinsing.

Physan 20 will not damage leaves or roots when used in the recommended dosages, making it safe to use around all plants.

Physan 20 does not leave permanent residue on leaves or plant matter; it breaks down into the organic compound Nitrogen after 7 days so there is not a chemical residue left over that would be harmful if ingested or smoked.


Physan 20 can be used in hydroponic systems to: 

  1. Prevent the development of disease
  2. Kill algae that may form on system surfaces and substrates


Please remember that Physan 20 is a potent liquid concentrate, which must be extensively diluted for hydroponic applications. This means that in some cases, only a drop or two of the concentrate will be sufficient in a volume of water to create the correct dilution. Do not be tempted to use more Physan 20 than directed and always measure when mixing. NEVER estimate by eye the amount you add to water.



Cleaning Hydroponic Systems Between Crops with Physan 20:

Physan 20 is an excellent product to clean and disinfect your entire Hydroponic system between crops. It may be used on plastics, metals, glass surfaces and is safe to run through delicate pumps and meshes.  

TO USE:  Mix 1 Tablespoon Physan 20 in 3.7 Litres of water to create a disinfecting solution. This may be used to apply directly to hard surfaces via a spray bottle or clean sponge. The wet surface should be scrubbed if visible dirt or algae are present. Make sure the surface remains wet for 10 minutes to ensure killing of all organisms Physan 20 is capable of killing. You may also run this dilution through your hydroponic system to clean and disinfect it.  

Physan 20 contains a foaming agent. At this dilution, you may notice foaming if you run the product through your system and you run aeration. This foam is harmless. If it is particularly bothersome to you, you may add a commercially available de-foaming agent.


Please note: The Physan 20 instruction booklets state that Physan should not be used in “irrigation systems”. This wording refers only to OPEN irrigation systems that dump water that might be treated with Physan 20 into ponds, lakes, or any fish bearing water. Physan 20 is toxic to fish. It coats their gills and interferes with their breathing. However, hydroponic systems are considered CLOSED irrigation systems that do not endanger fish. Physan 20 can be used in this closed system.



Algae Control on Rock Wool and Other Substrates:

Physan 20 can be used to treat rock wool and other growing substrates to eliminate algae both between crops and in the presence of plants. You must use different dilutions for each of these applications.

TO USE ON ROCK WOOL/SUBSTRATES BETWEEN CROPS TO TREAT ALGAE: Make a dilute solution by adding 1 Tablespoon of Physan 20 to 3.7 Litres of water. Soak the cubes in this solution for 10 minutes. Remove cubes and let dry. Do NOT plant in the cubes for 7 days.  This allows for a complete kill of algae and a breakdown of the Physan 20 active ingredients so that tender plants are not harmed upon planting.


TO USE ON ROCK WOOL/SUBSTRATES ALREADY PLANTED TO TREAT ALGAE: Make a dilute solution by adding 1-1/2 teaspoons of Physan 20 to 3.7 Litres of water. Put in a sprayer bottle and spray the surface of the rock wool substrate where algae is present. Let the sprayed surface remain wet for 10 minutes. You may also use this same dilution to spray the entire plant as well as the affected surfaces for complete pathogen control. If algae persists, apply again in same manner in 7 days. Measure carefully and DO NOT increase the concentration of the Physan, as crop damage can occur.



Using Physan 20 to Control Root Rot & Algae:

An important item to note, if you want to apply Physan 20 to the water where the plants roots are sitting and constantly exposed to the solution, then you must dial back the Physan to water ratio dramatically. This is primarily for if you are trying to control root rot or algae in your reservoirs. The ratio here would be 1 ml to 40L of water. This ratio may seem insignificant, but it is a safe dosage to start with so as not to damage any roots or plants. After witnessing the first round of effects, one can then increase the Physan ratio to what they see fit - within reasonable dilutions of course. e.g. it would be safe to up the dosage from 1ml per 40L to 2 or 3 ml.



Adding Physan 20 to Nutrient Solutions:

Adding Physan 20 to organic nutrient solutions may reduce or negate completely the algae and pathogen-killing capabilities of Physan 20. As Physan 20 is pH neutral, its addition will not change the pH of the nutrient solution. However, it should be considered that tender root systems are potentially at risk from a continual bath of Physan 20 solution. Because we cannot know what type of plants you are growing and what nutrients are being used, we can give no guidance as to the combining of Physan 20 with nutrients.



Physan 20 as a Foliar Spray for Pathogen Control:

Physan 20 can be applied to plants as a foliar spray to control pathogens.  However, it is NOT an insecticide and will not kill aphids, mites, scale, or pests of this sort. Physan 20 leaves no harmful residue if foliage is dried and smoked.

KEYWORDS: hydroponics auckland, nz hydroponics, hydroponics new zealand, hydroponic fungicide, control algae, hydroponic algae, mildew, hydroponic disinfectant