5.4 Quality control
The VitaLite-E and C plays an essential role in the water management of your
greenhouse operation. That is why the operation of the VitaLite-E and C must be
checked regularly by taking water samples and having them tested by a certified
laboratory. Ridder Growing Solutions recommends the following quality control
procedure:
Carry out regular CFU tests. A CFU test determines the bacterial count or colony
forming units (CFU) in the water. The bacterial count or CFU is the number of
bacteria that are present in the water.
Please bear in mind the laboratory's requirements when collecting and storing
samples for testing. CFU samples can age quickly, especially if the sample is
not kept cold.
Take a sample of the drain water (influent) and the disinfected water (effluent)
for a DNA test at least once every six months. Storing the sample in ethanol will
prevent the sample from ageing. Since a DNA test also measures the DNA of all
killed micro-organisms, an RNA test is more accurate.
The performance of the VitaLite-E and C depends on the transmission value of
the water. The transmission value T10 in [%] is the quantity of UV-C radiation
that can penetrate a column of 10 mm of water. If the measured T10 value is
lower than the value for which the VitaLite-E and C was designed, it will affect
the performance of the unit.
5.4.1 Sampling procedure for CFU testing
The description below relates to the VitaLite-E and C. Always read and follow the
instructions of the laboratory performing the tests.
Requirements
Sterile sample bottle (150 ml); if in doubt, sterilize bottles on site with alcohol
Alcohol in spray bottle
Burner
New latex gloves
Bucket for capturing tap water
Cooler with cooling elements or ice packs suitable for flowers (4°C / 39.2°F)
Prepare labels with the following information for each of the samples:
Customer details
Disinfection method (UV-C)
Sampling location (where was the sample taken)
Date and time that the sample was taken
Indication if the sample was taken before or after passing the quartz
pipes
T10 value, and if the VitaLite-E and C is working correctly
Preparations
Check the delivery days of the laboratory. Many laboratories do not accept
samples on Friday, Saturday and Sunday.
Make sure that the sample is cooled immediately after it is taken and is ready
for transit (preferably by courier).
VitaLite
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