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Oliver
12-22-2011, 08:57 PM
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."

urbanfarmer
12-22-2011, 09:32 PM
Yea, could be true, but it could just be garbage and folklore. People don't have a clue, that's my experience. Notice not any of those people discuss the actual mechanics of what is going on. They make one observation and connect it to another, WITH NOTHING TO PROVE IT. I agree Oliver, I still have yet to see why the use of a UV sterilizer is needed or even wanted (except for turbidity as mentioned by foodchains).

foodchain
12-23-2011, 05:13 AM
I could be off base here...but how does LIGHT remove a mineral?

The claims that they are expensive to run are off base....how expensive they are at purchase and to run depends on how big you go. You don't need a big one. My first I beleive was 8 watts? or something like that...it's been years and I no longer have the unit. But it wasn't much at all.

Apparantly the UV sterilizer is more of a personal taste type thing. No you don't have to have it...especially if you are growing 12 goldfish in a barrel. But it should be at least considered when someone is dealing with larger concentrations and higher volumes. Compare the cost of it, to the cost of total replacement of livestock.

I have run mine for several years, to date, nothing to my knowledge has suffered from nutrient loss. I have killed many plants, but I don't believe any of them were due to nutrient deffeciency. Usually it's something like the strawberries getting some salt or something like that. I can't blame the UV though for my errors.

urbanfarmer
12-23-2011, 01:55 PM
I could be off base here...but how does LIGHT remove a mineral?
It is possible, but without researching the possibilities... and furthermore seeing if it occurs in systems under certain UV lights... I will not comment either way on it. With that said, how are these knuckleheads so sure they definitively figured it out? I highly doubt they have. Soil and water chemistry is not as easy as it sounds (and don't be fooled, this is what we're talking about).

davidstcldfl
12-23-2011, 05:17 PM
I could be off base here...but how does LIGHT remove a mineral?

'?'....maybe something is happening to the water where the minerals are not being 'picked up' and used by the plant.

urbanfarmer
12-23-2011, 07:47 PM
I could be off base here...but how does LIGHT remove a mineral?

'?'....maybe something is happening to the water where the minerals are not being 'picked up' and used by the plant.
You mean they precipitate and are no longer bioavailable to the plants? Sure could be. Happens with iron without any UV lights added to the system... :ugeek:

foodchain
12-27-2011, 05:28 AM
Either way...the arguement stands. AP was designed originally to be a way to remove excess nutrient build up in commercial aquaculture closed loop/semi closed loop systems. Through that process, the veggies we enjoy now became a notable byproduct. AQ systems have to be "balanced" too, or they collapse in similar ways. So the arguement that the uv light is sin of all sins in an AP system by killing the required bacteria is not substantiated.

The arguement of wether or not they are good for you, and your system comes down to personal choice....as I have said all along.

There's standing evidence, that the higher the concentrations of your aquatic life, the higher the probablility of you having an outbreak. This is proven in a great many industries within agriculture/aquaculture and I feel it's redundant to source this but if anyone needs please PM me.

So, do you need UV? IMO it depends on how far YOU decide to push YOUR system. It depends on YOU and how much you demand from your system.
6 goldfish in a 600 gallon system, no....
2 tons of fish in a 10,000 gallon system? You see where I am going. Even at a wholesale value $2/lb, 2K * $2 = a hell of a risk. IF you don't have it, and you get an outbreak of say...anchor worm. What are you going to do?
Whatever holistic treatment you want to use, is still going to cripple the budget when multplied out to treat 10,000 gallons. In little Johnie's 10 gallon tank it's much more affordable to do treatments like this. But it's simply not practical on larger, more intensified systems. Preventative medicine is really the only option.

In a more intense system, you will still have the same anchor worm out break, but it's much more contained and as the parasite cycles through it's life cycle a UV sterilizer would minimize the impact allowing the manager/keeper to identify the problem, and administer treatment accordingly. IF nothing else the UV buys time before a mass epedimic breaks out.

So you all are right, it's not Required. But it sure as hell is nice. It's peace of mind. It's a natural way to prevent/treat problems that can occur. And it's cheap.

An ounce of prevention, is worth a lb of cure.

Any mineral changes that may occur, I have yet to witness. System has been operational for more than 3 years. It is possible that it's occuring, but if it is it must be in a cyclical process similar to the DO levels cycling throughout the time of day/night.

I have yet to notice or document any long term disadvantages of UV. If it were to kill ALL needed bacteria. My system would have crashed within the first 6 mos. If it removed ALL the minerals, I wouldn't be growing much...not right now as it's winter, but during the "on" season. Iron is an excellent example. Commercial fish food has iron added, this could be why it's not noticed.
I have not monitered this, as I previously didn't see a need. If it grows, I have always left it alone.
But if there was a true iron deff. wouldn't the plants be turning yellow and experiencing fruit drop?

With that being said, it's quite possible that any mineral changes go in cycles. Like winter/summer cycle. Summer grows more than winter, winter crops are limited by amount of light and temps.

What is clear to me. Is that there is a lot that goes on here that we don't quite understand yet, perhaps it's becuase we haven't measured it yet.

absolutely fresh
08-29-2013, 05:54 AM
I know this is an older topic/post and if it has been resolved/solved since I apologize in advance for my redundancy.
I have a small system thats been running off of my koi pond in my front yard that has a UV light incorporated before the plants and they are thriving! So as far as I can tell the UV light by no means is taking anything away from my plants or pond. I don't have any "scientific proof" of this other than physical evidence of the plants thriving. I have 2 yellow cherry tomato plants, 4 strawberry plants, and 2 cucumber plants planted in the system currently. With about 10 6-8" koi in the pond and one lilly plant. The water is pulled through a pad filter then pushed through the UV light then into the small system. If anyone would like I can post pics later.

JCO
08-29-2013, 06:10 AM
Welcome to the forum. New blood and brain power is always appreciated.

Photos are always appreciated. Show the entire system including the pond. Also, I agree with your assumption, as long as the UV is used after the bio-filter, the only bacteria it kills it that which would go to the grow beds and actually have a minimal effect on nitrates. :mrgreen:

Aloha Don
08-29-2013, 10:40 AM
Welcome fresh.
YES. Please post pics.
Thanks for your input.