Why You Should Use Physan 20 Instead of Bleach/Hydrogen Peroxide for Your Plants and Greenhouse:

Many growers recognise the importance of disinfection in the greenhouse. However, many mistakenly believe that chlorine bleach is a better alternative that provides quality disinfecting capabilities. This is not so. Chlorine bleach is not labeled for use as a greenhouse disinfectant by the EPA on a state or federal level. Infact, Its use as such can result in citations and fines upon inspection. 

Bleach is a solution of sodium hypochlorite and water. In its pure form it contains 12% chlorine and will corrode or destroy most metals, react with acids, peroxides, and other chemicals to produce toxic chlorine gas. Bleach will also dissolve paper, cloth, and many other organic materials and the utmost caution must be used when working with bleach. Even in a diluted form the fumes can produce severe irritation to the respiratory system and safety equipment must be used. Skin contact can result in mild irritation to burns and prolonged eye contact can cause permanent damage. Bleach presents a serious risk to employees who inhale the fumes or splash the product on clothing.

On the other hand, the diluted Physan 20 solution is safe enough to dip one’s hands in, it is not a primary eye or skin irritant, and if splashed on clothes will not harm them. The Physan 20 solution is pleasant smelling and requires no special ventilation to use.

Bleach rapidly evaporates when prepared in a solution. The half-life of a 5% solution of bleach and water is only 2 hours. Thus the prepared solution must be applied immediately after mixing to be effective. In addition, a contact time of 30 minutes is required for disinfection with Bleach.

Physan 20 on the other hand has residual germicidal activity, which means it remains effective for a period of time, particularly on hard surfaces. In addition, a 10 minute contact time is all that is required to disinfect with Physan 20. 

While the only real positive that bleach has is in its inexpensiveness, the rest of its variables are all negatives. Bleach is highly corrosive, toxic to all plants and mammals, contains toxic fumes, dissipates quickly, damages fabrics, causes irritation to the eyes and nose, has no cleaning ingredients, dulls floor tiles and can damage your floor finish! Why would you even risk it?

Admittedly, the only disadvantage of Physan 20 is its price in comparison to bleach, however the rest of Physan 20’s variables are opposed to bleach and speak for themselves.

Physan 20 has a far longer shelf life, is safe for both plants and mammals when mixed with water and is absorbed by plants systemically. It is EPA approved as a broad range fungicide and disinfectant, can be used in a wide variety of ways for a multitude of purposes, is safe to handle when mixed with water and doesn’t need specialised safety equipment!

With that said, it is easy to see why Physan 20 is the absolute winner when compared to Bleach and Hydrogen Peroxide.



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