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UV Sterilizers in Aquaponics for balancing Redox?!?

I was doing some research on water chemistry in aquarium settings to better understand what's going on in my AP system and read this article: which mentions UV sterilizers and their importance in maintaining Redox balance in aquariums and ponds. I subsequently read this article: which went into more detail.

Has anyone had any experience with this? "Supposedly" using a UV sterilizer would help maintain Redox balance and aid in parasite and disease control and immune function all while leaving the beneficial biofilter unaffected. I am a little skeptical.....I guess it would depend on where the biofilter lives in an AP system. Is it all in the growbeds attached to the media (in which case UV sterilization might work as advertised) or is it free floating (in which case UV sterilization definitely would not)?

Just curious! The concept took me by surprise and made me wonder if it had any application in AP or if it's just fluff.

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I have been reading a tone of info about UV.   I believe that UV would be beneficial to a AP system.  UV cant really hurt the system unless they are sized incorrectly.  

never had any problems without UV.. you have to ask is there any real gain?



Why would you want to complicate things with a UV steriliser? I guess I'm asking, how would it benefit the aquaponic system?  Would it impact the bacteria that are driving the system? I'm just curious... 

I'm not really sure if there would be any gain or not, which is why I was curious. The "promised results" were certainly intriguing, but rarely does anything work as advertised anymore. I stumbled upon the concept while researching my low KH/pH instability issues and was curious if anyone had heard of the concept in conjunction with AP. It seems to be used extensively in koi ponds, and since the nitrifying bacteria seem to be attached to surfaces as opposed to free-floating, the biofilter should technically be unaffected.

The only information I could find regarding UV and AP was in forum discussions where one person had success in clearing up an algae problem with short-term use and another had iron precipitation and staining as a result of long-term use.

It might be a useful tool for short-term use (a couple of days at a time) in clearing algae problems or in cleaning up a tank after disease is discovered without having to take drastic measures like total system sterilization and re-cycling, but this is just hypothesizing since I haven't seen any articles or research on the matter.

Obviously, once your system is mature and you have figured how to balance it properly the need for such a tool would likely be zero....and if your system runs beautifully why mess with it?! But if your system is struggling with algae, disease, or chemistry issues and you've got nothing to lose, could it be of benefit? Don't know!

But UV will kill the beneficial bacteria and that's what is powering an aquaponic system. I'm just sayin...  Check out the Bright Agrotech video channel on YouTube.


UV sterilizers are a bad idea in aquaponics. The whole process works off of bacteria, which is what this type of product tries to eliminate.

It sounds like the general consensus is that it is a bad idea. I sort of figured that was the case, but I couldn't find anything solid one way or the other and curiosity got me so I had to ask. Thanks for your comments!

UV sterilizers Do Not Kill beneficial bacteria.  They only kill bacteria that are floating in water, and those bacteria do not belong in the system.  UV used during cycling after the introduction of liquid beneficial bacterial could be a problem.  Below is a well written article about UV Sterilization and its uses.  I have read many articles about UV but i think everyone will like this one.  This website also has a lot of other useful information.

There are Many Benefits to UV.  Hear are a couple that i can think of. 

1)UV's help balance ORP.  ORP stands for Oxygen Reducing Potential.  ORP affects the mineralization of the system drastically.  ORP meters are also the only effective electronic measuring tool that can be used to judge how sterile an environment is.  Higher ORP readings means less diseases.  A ORP reading from 275 to 375 will result in a 90% reduction of a bad bacteria.  An extremely low orp will actually cause denitrification.   I have a Neptune Apex controller that has a ORP probe.  The Neptune Apex graphs the ORP and can be programed to take corrective actions if needed.  I read my ORP graphs daily  to judge the health of my system.  If my orp starts to go down i know that there is something wrong.  For Example. I have grow beds with bell siphons.  One of the bell siphons failed in the full state and did not drain.  This cause my ORP to go down.  Dead fish can also cause ORP readings to go down.  Also If your ORP starts to go to high it is a sign that there is a lack of minerals in the system.  Most of the minerals that a supplemented to a AP system are reducers that lower ORP.

2)UVs can help control algae.  As anyones AP system starts to get older it will most likely start to have algae problems.  There are some fish that eat some types of algae like String algae but....  String algae will not grow in waters with high ORP, and my system will be running in the 350-400 range so i don't have that problem.  Although Green water algae does grow in my system  and fish wont eat this type of algae so a different approach mush be taken.  You could leave the green water algae but it is consuming nutrients that the plants could be using, and the green water algae makes it hard to see your fish as it clouds the water.  There are only 3 ways that I know of to get rid of Green water algae.  One, you must block light from hitting the water.  Two, you remove nutrients from the water, and three, you add a UV.

3) High Wattage UVs Kill everything as it passes though UV.  This is a higher level of uv treatment and requires a higher wattage bulb.  For normal operation of the system i would not recommend this.  For my 500 gallon system I plan on getting a 15 watt UV light and passing 250 gallons per hour through the UV 

Are UVs necessary?   No

If your just starting are UVs going to be on your shopping list?  No 

If you have bought everything under the world for your system and you like cool gadgets would buying a UV help the system?  I would say YES!

 If you do buy a UV know that it MUST BE SIZED correctly as adding a UV that is lo large could cause more harm than good.  Start with lv 1 uv treatment which is a low wattage treatment.

Enjoy your UV  

Jonathan - Thanks for your post, I'd be very curious to hear how the UV works out for you. Will you update if you are brave enough to go forward with it? I am also intrigued by your measuring of redox potential to judge stability in your system. I'll have to do some more reading on that to try to better understand what you are doing there. I guess only time and experimentation can tell if this is "crazy talk" or not. My hypothesis is that the nitrifying bacteria will be just fine since I don't think that they are in the water column but are instead attached to the surface areas of the tanks and grow beds (I think that they are a part of that nice clear slime that develops on the surface of everything). Whether there will be other effects (good or bad) resulting from using UV though I have no clue. Good luck!

Won't the UV cause chelated iron to un-chelate?'

This Link Will Explain How Iron Reacts In water. It includes detailed explanations of how reactions occur in water and how it relates to the ph and orp.  It is a little hard to follow. 

 I am still looking for how UV could harm any reactions in any negative ways.   

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