Backyard Aquaponics
A place to discuss aquaponics

I think this came up before but would running a thin film under sunlight (like a gutter under glass) kill stuff or cause it to get worse? Would that be any different than using a UV light over it? This assumes you don't mind it warming up the water.

Sunlight Contains light from the whole spectrum IR all the way through to UV. It would most likely grow algae faster than it can kill it...

UV disinfection by sunlight is often employed.... guess the diffference migth be the nutrient load of an AP system and the relative volume of water passing throught the gutter?

I suppose one could try and come up with a filter (now I'm talking about lighting gel or color media) that would pass UV and block most other wavelengths in the spectrum to incorporate into the sun trough UV thing! I wonder if that would block too much of the intensity though. Perhaps one of those solar thermal systems with a lighting filter to block all but the UV might work but it would probably burn out the gel on a daily basis.

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Well, the UVC stuff is supposed to cause algae to clump together and clairify the water.

The UVS is supposed to sterilize the water.

I think the conversation has been kinda about both

Free floating bacteria and fungal spores. Got to have clear water to do it.

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Don
Only use it when I have problems with the fish. Does not consume much power. The sunlight thing has problems with heat exchange and I would imagine algae growth.

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OK

I use two Emperor Aquatics 40W UV sterilizers on my system (total <300L). They are sterilizers, not filters- because they do not remove material from the system, but rater kill bacteria, fungi, algae, viruses etc. There are lots of reasons to use them and a few situations when they can have a deleterious effect on your setup- like when it is first set up and you have not yet established a biofilter, or when using certain medications. In all, they are a benefit to most systems, but do require care and maintenance- such as bulb replacement every 9-14 months depending on manufacturer, and requisite seals. Also, they can contribute a few degrees of heat to the overall system too.

As an example, my Zebrafish Facility uses six 80W UV's that are ~6 feet long for each of my three rows of racks (324 3L tanks, 162 10L tanks, plus three ~200L sumps) and we stock fish at 4-8 fish/L depending on age/purpose.

Flocculation of algae, or bacteria/biofilm is more a function of it having died and it's subsequent decomposition (as it decomposes it gets sticky and tends to floc) rather than an attribute of it's having been exposed to a specific propery of UV light.

And though it works best in clear water, turbid water is subject to the same deadly effects of UV. The design of these sterilizers ensures thateven heavily tinted liquids like pre-carbonated cola drinks are thorouly sterilized. Plus, given enough recirculated exposure, water that is turbid from anything other than suspended silt would begin to clear.

And nutrient load would be unaffected by all accounts, except that UV does not discriminate between harmful microbes and beneficial ones (e.g. nitrifying bacteria).

I disagree Wrangler... other than perhaps a few instances where you may want to sepcifically remove/kill bacteria or other substances.... IMO, they have no real benefit in AP systems...

Your water shouldn't require them, and disease issues are better dealt with in isolation tanks.. and/or dumping of affected water and medications...

Having said that... in AP we don't, and you shouldn't use any aquarium style medications... only approved treatments for edible fish....

And if your water quality is good then you shouldn't be having issues...

UV steralises... as you rightly point out... don't discriminate between good and bad bacteria... and any prolonged use will kill off your growbed colony...

Causing it to effectively "re-cycle"... with the attendant ammonia, and nitrite spikes... harmful to your fish, especially if they're large and near harvest...

Nothing really to be gained by using an external device, that can't be acheived by good design and water management... IMO...

First you qualify exceptions where they do have a place in AP systems, then you say they don't. It's hard to have it both ways. An application not yet mentioned here is when you need to sterilize source water- such as well water (during times of heavy rainfall when the water table is high and so the well is subject to exposure to microbes which are potentially harmful to fish and people).



Shouldn't and won't ever are two very different things. Correct, a healthy system may not need them, but the fact is that not every variable is under our complete control. Indoor and outdoor, things happen that can cause a problem, and you may not even know about it until it's too late. The field I work in, Laboratory Zebrafish culture, has had a few cases of this. In more than one instance a technician (just as easily could be a buddy stopping by to see you who has an aquarium/koi pond/AP system of his own, or was just out fishing) brought in the spores of a filamentous/hair algae under his/her fingernails after eating lunch at a nearby pond. The result was an algal bloom that gummed up the works of a multi-million dollar system so bad that it required the depopulation of more than a half-million fish and tens of thousands of dollars of labor and materials to sterilize and replace system parts, not to mention the loss of valuable research and fish lines. Lesson learned: Adequate UV would have prevented the bloom of an algae that caused untold grief.



This assumes that everyone using AP is doing with the intention of eating the fish they raise, and nothing could be further from the truth. Myself and a few other members here, as well of dozens of other people who have taken to the internet to discuss their AP systems use ornamental fish as well as "pet" reptiles and amphibians to power their systems.



But yet people DO experience "issues".



Your growbed colony will be largely unaffected as well. The only nitrifying bacteria coursing through your system is either sloughed and dead or simply pushed off the substrate as a result of it being at carrying capacity. Only microbes in suspension are subject to the killing power of UV. Claiming that use of UV will kill of your growbed colony illustrates your misconception of how the technology works. If it killed of the beneficial bacteria in a growbed, then by the same logic it would kill of the aquaria biofilter- it does not.

Causing it to effectively "re-cycle"... with the attendant ammonia, and nitrite spikes... harmful to your fish, especially if they're large and near harvest...



Tell that to the operators of Fish Hatcheries and Marine Parks and Museums. You can manage and design all you want, but you can't predict everything. You can, however, take steps to mitigate the effects of dangers seen and unseen. IMO.

Just a quick note on medications. Even if the fish in the system are not meant for consumption, you might want to do research before using aquarium medications if you plan on eating the plant products from the system.

Keep in mind that the "average" or "baseline" systems that this forum has been built on are backyard food systems so understand that generalizations about systems here are very likely to be generalizations about backyard scale food systems.

I know there are "other" types of systems out there but they often fall into something like Duckaponics or turtleponics or there is a whole section of the forum out there for commercial systems, granted, most of the members so far have been focusing on food production but I do know there is a huge industry of tropical fish production (and other similar things) that might become interested in Aquaponics just to assist in reducing the need for water changes. I would personally put this and the zebra fish stuff into the commercial ranks with the attendant concerns with protecting investments which are not usually worth the extra equipment costs to the average backyard system.