Thoughts on UV?

FutureInterest

FutureInterest

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I ran UV 14 years ago for a few years and never really noticed much of a difference... in fact the UV had died at some point and I forgot it existed... Part of the issue can be chalked up to my inexperience and perhaps I had too much flow going through it at the time.

In my current setups I'm not running UV but recently acquired a fairly large one in a trade for the hell of it and I'm wondering if there are any other benefits beyond ich control?
 
What is your goal overall ? Water clarity or water treatment? And what are you comparing it’s result to ?
 
How big is fairly large? Will you be running as a stand alone unit, or as a total pass through?

My thoughts are: Uv is great, when used properly
It’s also expensive to get a unit large enough to actually kill ich unless it’s hooked up to a 20g QT. Uv works great for clarity and for killing small diseases or stunting some parasites.


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There was a very long thread on UV which was pinned at the top of reef discussion (or similar forum name) on the old ARC site. I've been gone awhile, but will summarize-
How it works: In a nutshell, UV (approximately 290 nM wavelength) damages a specific bond in thymine, one of the four bases which make up DNA.
How much you need: This depends on several factors, including: flow, target organism(s), water turbidity, UV device geometry, etc.

The highest irradiance requirements to control aquatic pathogens I found published is for cryptocaryon irritans at 280,000 µWsec/cm2+(to over 800,000µWsec/cm2). This level may vary widely, has been extrapolated from other organisms (or is anecdotal) and is stated by UV filter manufacturers which mostly market themselves as water treatment companies based on a single pass treatment, as is required for drinking water. The efficacy actually depends on a statistical probability of the thymine bonds intercepting a UV photon.
Why does that matter to us? Because in an aquarium, we recirculate the same water (& organisms) through the UV device potentially multiple times. So, the probability of interception increases with time.
On the other hand, UV bulbs degrade with time (lowering their output), bulbs get dirty, etc.
All in all, a good argument can be made that the published power requirements (eg- watts per gallon) may be overkill.
The counter argument has been made that: Excess (ie- oversized) UV won't hurt anything (except your wallet!).

More info., related to sun damage, but still applies-
"When UVB light hits the DNA strand, it causes a change in the structure of the chain. Any place along the strand that has two thymine bases in a row is vulnerable to this damage. The energy of the UVB light alters a chemical bond in the thymine. The altered bond causes the neighboring thymine bases to stick to each other. This pair of stuck-together thymine molecules is called a dimer. Wherever these dimers are formed, the DNA strand is bent from its normal shape, and cannot be read properly by the cell. Every second a cell is exposed to the UVB in sunlight can cause the creation of up to 100 dimers. If a cell accumulates too many dimers, it can die or become cancerous."
https://sciencing.com/uv-light-damage-dna-strand-12687.html

For cryptocaryon control-
http://edis.ifas.ufl.edu/pdffiles/FA/FA16400.pdf
 
UV is a fantastic tool if implemented correctly.

In order to do that, you need to determine your goals: algal control, parasitic control, etc. Then, you'll determine the fluence rate you're wanting.

Most hobby UV's are nothing more than a POS heater and are not worth buying. If you do happen to get a good one, it'll set you back a bit, but it'll be so worth it. Like @ichthyoid said, you'll need to maintain the lamps. The good ones will last you a year (they'll be running at 120% of what you need when new, and at 80% at the end - estimated numbers for illustrative purposes only).
 
I just cleaned out my sump and realized water was in the bulb chamber. Was wondering why I was getting zapped everytime I put my hand in the water. Does that effect coral? I know fish it doesn't really bother.
 
brian stewart said:
I just cleaned out my sump and realized water was in the bulb chamber. Was wondering why I was getting zapped everytime I put my hand in the water. Does that effect coral? I know fish it doesn't really bother.
Click to expand...

I had a bulb go bad, no water inside the chamber, I was getting zapped too. Didn’t notice any effect on fish or coral, I’m sure they don’t like it though. It has to create some sort of stress.


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Thanks guys. I don't need UV for parasite control or for algae control. The systems are all doing well in both regards so I'm just going to get rid of it.

As for the electrical current in the water... I remember there was some research from long ago that stoney corals grew faster with a slight current in the water... something about it helping calcium carbonate form faster... :) It was so long ago I can't be certain...
 
"This paper provides the first overall review of the data. Low-voltage direct current trickle charges are found to increase the settlement of corals 25.86 times higher than uncharged control sites, to increase the mean growth rates of reef-building corals, soft corals, oysters, and salt marsh grass— an average of 3.17 times faster than controls (ranging from 2 to 10 times depending on species and conditions), and to increase the survival of electrically charged marine organisms—an average of 3.47 times greater than controls, with the biggest increases under the most severe environmental stresses."

https://www.scirp.org/journal/PaperInformation.aspx?paperID=48444

So, a major point is the "Low-voltage direct current trickle charges " part.
Which is a significant departure from 120VAC household current (especially if the tank water is grounded).
 
Wow. Look at you man. Ask and you shall receive. Thank you :) Wish I could give you more than one like.
 
One common denominator I see in most successful long term systems is that they all have UVs that far exceed the standard size recommendations. They almost all have said that an oversized UV is one of the key factors in their success. Just food for thought.
 
I have an Aqua UV 57w unit that I run from 9am to 9pm. At my current tank volume it's still a bit over sized. The flow rate through the unit is slow enough that it is probably even a bit over kill through it. I just don't have the means to push their recommended flow through it. I don't run it at night because there are a lot of pods and other things that get in the water column at night and that's also when I dose Phyto. If nothing else I can say that it helps greatly with water clarity.

I clean the quartz tube quarterly and change the bulb every 12-14 months. It's fed through a manifold and is programmed to shut down any time the main pump is off with a 2:30 delay once it comes back on.
 
As the link illustrates, 185nM UV is generally more efficient/destructive to a wider range of organic bond types than the 254nM UV we use in our sterilizers.

However, the 185nM lamps are not practical, as that wavelength does not penetrate water well due to absorbance and the lamps are expensive.

The 254nM is absorbed well by benzene rings, which are widely present in organic chemistry, including many pigments and phenolic compounds (think that yellow'ish color tank water can get).
 
During the data conversion we couldn't fix certain things. So some links, formatting and images can be messed up.
When I get a chance I'll clean that thread up and resticky it.
 
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