Quotes from around the web on UV Sterilizers regarding minerals.

Oliver


Murray 18th June 2007 AquaponicsHQ forum.

"I have run UV light sterilisation as part of my Bio-filter. The manufacturer of the Bio-filter assures me that the UV light will not destroy the Bacteria. (bit hard to believe)

"What the UV light will do is remove Iron from your aquaponics system and seriously deplete Boron and Manganese. The evidence for this is compelling. Tomato plants in particular suffer badly.
Muzza"


Murray 18th June 2007 AquaponicsHQ forum.

"I would not go with the UV light. I used it to get rid of the bad algae problem I had at the time. That is the main reason I installed the bio-filter with UV light. It was just amazing how it cleaned up the water and the algae.

"It worked extremely well.

"I was so impressed that I decided to leave the bio-filter in the system.

"It was not until 3 or 4 weeks later that I noticed the leaves on my tomatoes becoming very light in colour and with prominent dark coloured veins. The fruit I was picking at the time ripened with patchy colour. A bit strange.

"I had the Science Master from a Brisbane Northside school visit to look at my system and he told me what it might be. (mineral deficiency)

"I got GaryD to come and take a look and he confirmed the deficiency of Iron, Boron and manganese due to the use of a UV light in the water circulation. Evidently GaryD has seen this problem recoded before by hydroponics people in their writings.

"I was puzzled as to why my system should be mineral deficient as I am in the habit of applying mineral rock fertilizer and initially not believing the theory of mineral deficiency.

"The UV light proved to be the missing piece in the jigsaw puzzle.

"On switching the UV light off and adding some mineral rock, the tomato plants recovered over about 4 weeks.
Muzza"


Other quotes from the web:

"Iron and Manganese ions oxidize and precipitate out of solution causing problems of staining and nutrient deficiency. This process is exacerbated when the water is sanitized with UV light."

"Ultra Violet (UV) sterilization is one of the most successful means to control root diseases such as Pythium in hydroponic systems. However the continuous use of UV will cause certain mineral elements to drop out of solution very quickly. For the hobby grower, with a small tank, this can cause major problems within days."

"Remember that UV kills diseases very effectively but it also precipitates specific minerals from the tank."

"The (UV) biofilter is a cost-effective alternative to other forms of water disinfection.* Many growers use ultra-violet sterilization in recirculating hydroponic systems, but UV is expensive in electrical costs and it has some detrimental side effects, such as the oxidation and precipitation of iron."

"Many growers have found that Ultra Violet Sterilizers are an ideal way to control root diseases like Pythium. Ozone Generators are even more effective for this task and are rapidly becoming more popular. However the use of these devices will strip certain minerals out of the solution in very short time."