Water treatment series

Over the last two years many parts of the continent have experienced problems with water quantity or quality. Water is a major issue for horticulture. Drought conditions and water restrictions in the Southeast are forcing companies to adapt or go out of business. With increasing urbanization, water-management authorities are regulating supply and runoff as growers and landscapers compete with both rising consumer and commercial water demands.

Part 1: Treatment options

A big-picture perspective is required to evaluate the overall flow of water in an operation. A water-treatment specialist can help to identify the potential points of contamination that can lead to the correct combination of technologies needed. There is no one silver bullet when it comes to water treatment. Many technologies work. The questions that need to be answered are which are the most cost-effective, how do they interact and how can they be used effectively?

Part 2: Waterborne pathogens

Your greenhouse can be equipped with the best (and most expensive) water-treatment system available, but still run into disease issues. That is because water treatment is just one part of an overall sanitation program. Understanding the biology of waterborne pathogens can help you use preventive management and chemical disinfestants more effectively.

Part 3: Filtration

Ask a group of growers about using filters in irrigation systems and nearly all will agree that it’s important to have one. Ask them about what’s the best mesh size for the filter cartridge and about half will answer correctly. Lastly, ask this group to relate mesh size of the cartridge to micron size and the percent with the correct answer will dwindle to single digits.

Part 4: Sodium, calcium hypochlorite

Calcium and sodium hypochlorite are widely used to control waterborne pathogens and algae in irrigation water. You are probably most familiar with these materials as liquid bleach (sodium hypochlorite) and solid swimming pool "shock" (calcium hypochlorite). Understanding water chemistry is important so you use these materials safely and effectively.

Part 5: Chlorine

Chlorine can be used to kill pathogens, bacteria that are harmful to human consumption, as well algae and iron-forming bacteria that clog filters and nozzles. Chlorine also provides residual protection by treating water as it travels through the irrigation system and out into the greenhouse or nursery.

Part 6: Gas chlorination

Water can be treated with chlorine gas to control Pythium and Phytophthora as well as algae and slime from iron bacteria.

Partnerships lead to water alliance

This series is part of the Water Education Alliance for Horticulture initiative (www.watereducationalliance.org) supported by AquaHort by LHT, BioSafe Systems, Ellegaard Göttingen Minipigs, Fafard, Fischer Ecoworks, Greencare Fertilizers, Griffin Greenhouse and Nursery Supplies, Hanna Instruments, Konjoian’s Floriculture Education Services, National Foliage Foundation, Pindstrup Mosebrug, PPG Industries, Premier Horticulture, Quality Analytical Laboratories, Regal Chlorinators, Sun Gro Horticulture, TrueLeaf/Aerotech, University of Florida, Whitmire Micro-Gen and the Young Plant Research Center partners (http://hort.ifas.ufl.edu/yprc).

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Workshops on water treatment are being conducted at the OFA Short Course, Plug and Cutting Conference, and other events supported by the alliance. Information on these events and additional water treatment resources are available online at the alliance Web site, www.watereducationalliance.org.