UV Sterilizer - Pros/Cons for a freshwater tank

[CoSpy]

Regarding the UV STERILIZER, can you use it periodically as a preventative, or only when you suspect or see a problem.  What does it do to the fish that are established living in the tank?  Someone posted there's a chemical alternative that does the same thing.  Would this be less invasive for the fish?  Is there a chart as to what size or wattage one needs?

[KBOzzie59]

This is they style I use, you have to provide the pump/power-head.

Here is their sizing chart.  

https://aquaultraviolet.com/wp-content/uploads/2019/06/UV-Chart-Fresh-Water-Web.pdf

 

[Biotope Biologist]

In my personal experience it seems they are best used in the quarantine tank environment where there is no substrate or particulates in the water. Any particulates or total suspended solids will block the light from penetrating and irradiating cells, thereby making it less effective. As an antibacterial and microbial they work incredibly well. As a means to combat algae they work as advertised, but don't eliminate the problem. They only kill free floating algae so I found myself still scrubbing the plastic ponds of algae every few days. UV can cause damage to the scales or skin of fish, but most products are contained within a quartz sleeve and plastic protective sleeve to prevent extended exposure.

 

Here is a chart as well for you to peruse:

UV Bulb (Watts)	Maximum Flow Rate for Controlling:		Aquarium Size
	Bacteria and Algae	Parasites
8	120 gph	N/A	under 75 gallons
15	230 gph	75 gph	75 gallons
18	300 gph	100 gph	100 gallons
25	475 gph	150 gph	150 gallons
30	525 gph	175 gph	175 gallons
40	940 gph	300 gph	300 gallons
65	1700 gph	570 gph	570 gallons
80	1885 gph	625 gph	625 gallons
120	3200 gph	900 gph	900 gallons
130	3400 gph	1140 gph	1140 gallons

 

credit: liveaquaria.com

[Guppysnail]

Up contained harmless to fish...chemicals although non toxic somewhat stress your fish by forcing the liver kidneys gills etc to work harder to expel the chemical from the body.  The on/off is what kills bulbs. Yes they wear out over time and become less effective but, on of makes them stop all together.  I leave mine on all the time ...why....it makes ME feel better like I might be lowering the bacterial count all the time. True not true who knows. I feel good about it

[tonyjuliano]

I think that UV, in a freshwater environment, is a bad idea.  

On the positive side, the potential for direct harm to fish is practically nil, as exposure is relegated to only substances that are directed by flow through the light chamber.

Indirect harm may be another matter.  There are many organisms (some algae included) that are beneficial in maintaining a healthy environment, and UV exposure is not discriminate in its approach.

There is also logistical difficulties in implementing this.  Notice the chart lists “maximum” flow rates for effectiveness.  This is because the flow has to be relatively low in order for the organisms to be presented to light exposure for an adequate period of time.  There is no residual effect after leaving the chamber.  This makes it practically impossible to install a unit inline with filtration flow, as in almost any case flow rate would be too high.

The bulbs are also expensive, and their effectiveness diminishes rapidly with run time.

A healthy aquarium is not a sterile one.

Edited June 18, 2021 by tonyjuliano

[Biotope Biologist]

On 6/18/2021 at 9:48 AM, tonyjuliano said:

A healthy aquarium is not a sterile one.

I wanted to say this as well but didn't want my wall of facts to be negated by my own personal opinion. Thank you for saying it so I didn't have to.

[HH Morant]

A UV sterilizer "kills" algae, bacteria, and some disease organisms (ich) in the water passing through the device. It doesn't actually kill the bacteria/organisms, it only makes them unable to reproduce (sterilizes them). There are UV sterilizers designed to be placed in the aquarium and others designed to be placed on the return line between the filter and the tank (after filtration). UV Sterilizers are best left on 24/7 (the bulb actually lasts longer that way). The units designed to be placed in the tank shield the fish from the UV light, so it does not affect them. The UV sterilizer will not affect algae, bacteria, or organisms existing on surfaces in the tank. See aquariumscience.com article listed under "equipment."

[Cys aquatics]

Here is the UV Sterilizer that i use for two of my biggest tanks ( 37 gallon, 29 gallon) and it works perfectly and i have never had an algae bloom since i started using them. I personally don't think that there is anything wrong with this UV Sterilizer, it is a little bulky but if you get some tall plants to cover it it's fine. This UV Sterilizer is good because it has some good flow and is just over all a good UV Sterilizer. The name of it is "COODIA Internal Green Water Killer Filter Aquarium Tank U-V Pump"

Edited June 18, 2021 by Cys aquatics

[tonyjuliano]

On 6/18/2021 at 1:08 PM, HH Morant said:

UV Sterilizers are best left on 24/7 (the bulb actually lasts longer that way).

I disagree with this statement whole-heartedly…

The greatest factor in “lifetime” of light output, in regard to ANY type of bulb, is the amount of time it is energized.

This is akin to the false analogy that adjusting a thermostat to a higher or lower temperature than actually desired to maintain, will heat or cool the environment more quickly.

In both cases, this is just false.

 

Edited June 18, 2021 by tonyjuliano

[KaitieG]

All I can give is my personal experience--no absolutes or hard research here--I had issues with cloudy water, no matter how much I changed lighting, feeding, filter floss, etc..  I ready Cory's guide on cloudy water causes, tried a UV sterilizer (since I'd already tried everything else) and the water was crystal clear in 3 days.  I've run it once for a 12 hour period since. 

I put mesh over the intake to keep fry from getting in, and I'm very happy with how it's worked for me for algae.  I didn't have disease issues that I was trying to fix, and I wasn't trying to sterilize my whole aquarium setup--I just wanted clear water!  And it worked for that with no observable change in parameters, fish behavior, health, etc..  I know it's increased my enjoyment of looking at my tank by about 1000X, so that's been worth it to me!

This is the one I bought--price seems to go up and down.  I paid about $37. https://www.amazon.com/gp/product/B07DFR6CRQ/ref=ppx_yo_dt_b_asin_title_o09_s00?ie=UTF8&psc=1

[HH Morant]

Will Rogers said "All I know is what I read in the papers."  I haven't tested UV sterilizers to see how long they last, but lately I have been reading the articles in aquariumscience.com, so that is where my statement about bulb life came from. That site says that fluorescent bulbs (like UV bulbs) often fail when turned of and on frequently. The site recommends 24/7 operation rather than having the device on a timer to go on and off each day and says that will make the bulb last longer.

[tonyjuliano]

On 6/18/2021 at 2:36 PM, HH Morant said:

That site says that fluorescent bulbs (like UV bulbs) often fail when turned of and on frequently.

No…. The bulbs do not fail due to this.  The high energy ballasts that energize the bulbs do.  But only in the case where cheap quality ballasts are used.

And, if anyone is interested in the source, it’s “aquariumscience.ORG” not “aquariumscience.com”.

Edited June 18, 2021 by tonyjuliano

[CT_]

I guess I have a lot to say here so I'm bunching all my replies into one, especially because some are veering off topic. 

On topic:

Generally I think the advantage is you get clear water, less algae, and possibly less pathogens if they're there (I wouldn't pick a UV sterilizer to remove pathogens though).  Algae has to go through a planktonic phase so it'll spread slower with a sterilizer.  I've noticed less glass cleaning when I use mine.

The disadvantage is you kill all your microbes and critters that get swept up in it.  Most are though beneficial, at least on this forum.  But even if they're beneficial, you may not like them and if you don't like them and don't have to live with them then why not nuke them.  At the end of the day aquariums are for you so do what you like (as long as you're not a psychopath).

 

On 6/18/2021 at 11:42 AM, tonyjuliano said:

No…. The bulbs do not fail due to this.  The high energy ballasts that energize the bulbs do.  But only in the case where cheap quality ballasts are used.

 

To add to this power cycling every 5 min is for sure a good way to wear out your ballast.  cycling once a day isn't much of a problem unless you're going for a world record in longevity or something.

 

On 6/18/2021 at 10:28 AM, tonyjuliano said:

The greatest factor in “lifetime” of light output, in regard to ANY type of bulb, is the amount of time it is energized.

I think this depends on technology.  true for LED, less true for tungsten and i'm not quite sure about fluorescent(if you exclude ballast failures).  For tungsten the heat cycling of the filament is a contributing factor as well.

On 6/18/2021 at 10:08 AM, HH Morant said:

It doesn't actually kill the bacteria/organisms, it only makes them unable to reproduce (sterilizes them)

I guess it depends on how you define death, but exposure to UV-C very much does kill, or result in the death of, microbes by damaging DNA making them unable to produce the proteins necessary to continue to live.  UV can also break and denature protiens.  As a side not sterilize has two meanings: to make free from microbes, and to make infertile. 

 

On 6/18/2021 at 9:48 AM, tonyjuliano said:

Notice the chart lists “maximum” flow rates for effectiveness.  This is because the flow has to be relatively low in order for the organisms to be presented to light exposure for an adequate period of time.  There is no residual effect after leaving the chamber.  This makes it practically impossible to install a unit inline with filtration flow, as in almost any case flow rate would be too high.

If it doesn't kill a microbe, there will still be residual effects in the form of damage to DNA and protein.  If given enough time they may recover but be left with permanent and most likely deleterious DNA mutations.  Given that the recommendation (not saying its right) is to have 4+ volumes per hour of water flow through filtration that's an average of 4 trips through the sterilizer per hour.  plankton doesn't die on it's first trip it will eventually.

[tonyjuliano]

On 6/18/2021 at 3:56 PM, CT_ said:

If it doesn't kill a microbe, there will still be residual effects in the form of damage to DNA and protein.

By “residual effect” it was meant to refer to the other microbes in the water column.  In others words, passing a number of microbes past the radiation source, does not innocuoate anything else in the water column.

The process of radiation itself has no residual effect on the body of water as a whole.

On 6/18/2021 at 3:56 PM, CT_ said:

I think this depends on technology.  true for LED, less true for tungsten and i'm not quite sure about fluorescent(if you exclude ballast failures).  For tungsten the heat cycling of the filament is a contributing factor as well.

No, the heat is greatest when a filament if fully energized, not when it is ramping up or down (turning on or off).

The reason that tungsten is chosen for the filament material in most incandescent bulbs is because of its very high melting point (it’s resistance to damage from heat).

Edited June 18, 2021 by tonyjuliano

[CT_]

On 6/18/2021 at 1:09 PM, tonyjuliano said:

No, the heat is greatest when a filament if fully energized, not when it is ramping up or down (turning on or off).

I said heat cycling not heat.  the mechanical stress of expansion and contraction causes wear.

 

On 6/18/2021 at 1:09 PM, tonyjuliano said:

By “residual effect” it was meant to refer to the other microbes in the water column.  In others words, passing a number of microbes past the radiation source, does not innocuoate anything else in the water column.

The process of radiation itself has no residual effect on the body of water as a whole.

I'm not sure what you mean by "innocuoate" here.  If I take a bucket of water with microbes, take half of the water, sterilize it and put it back, I've changed the the make up of the bucket of water.  Assuming its well mixed (granted not all aquariums have good flow) repeating that indefinitely will reduce the number of microbes asymptotically to 0.

[StevesFishTanks]

I use a UV sterilizer as the last step for my daily auto water change system. Not sure if needed but seemed like a cool idea.

[tonyjuliano]

On 6/18/2021 at 4:14 PM, CT_ said:

I'm not sure what you mean by "innocuoate" here.

Excuse the typo, I meant “inoculate”.  In other words, the “treated” portion of the water does not imbue the untreated portion.  Yes, of course the overall total of microorganisms have been reduced, but there is no residual effect on those not treated.  It’s splitting hairs, but I wanted to point out that “treatment” is limited to those that come to be radiated directly. 

[Jungle Fan]

I only use them when I have to. UV-sterilizers change the chelation of liquid iron and render it unusable to plants as I found out from the warning labels on some liquid iron varieties. So if you are dosing liquid iron to keep your plants happy that would be one negative to consider. Another negative is that the bigger the tank the bulkier the UV-sterilizer, unless you hook up an in-line sterilizer, at which point maintenance gets to be a bit more of a production, Lifetime of the UV-bulbs, and sealing are another negative and reason why as I said I only run them when I have to. For me they are a nice to have just in case, much like a diatom filter, but not a steady fixture in my tanks.

[tonyjuliano]

On 6/18/2021 at 9:03 PM, Jungle Fan said:

much like a diatom filter

Now there’s a vintage piece of equipment that is almost impossible to come by anymore!

Talk about tank clearing!  And fast!  I used to use one regularly, back in the day when I had big African Cichlid tanks.

I went searching for one not too long ago, only to find they pretty much don’t exist anymore.

Vortex brand!

Edited June 19, 2021 by tonyjuliano

[Jungle Fan]

@tonyjuliano I used to run a Vortex years ago too whenever something was cloudy. It was great  for clearing up a tank from the dust of new substrate, or laterite additions. Last year I was looking for one and all I could find was the Marineland Internal Canister Polishing Filter. At first I was a bit skeptical about that one but when I set up my jungle tank for a dark start I charged the micron filter cartridge with diatomaceous earth powder and within four hours every last bit of left over dust from the substrate was gone. Cleaned it up and it is now back in the box just in case, whenever that may occur.

[tonyjuliano]

On 6/19/2021 at 12:50 AM, Jungle Fan said:

Last year I was looking for one and all I could find was the Marineland Internal Canister Polishing Filter.

And that’s exactly what I ended up with…

The Marineland Magnum polishing filter.

Here’s a “before” shot of a tank filling using the super dusty Fluval Stratum substrate.

And after like 5 minutes running the Magnum.

I never even bothered rinsing before-hand (which takes FOREVER with Stratum), because I didn’t have to.

I do wish that it could be run externally, like the old Vortex, though.

[tolstoy21]

I've used UV and not used UV (not currently using one).

I used a very reputable, large UV sterilizer that I paid a premium for. I ran the light 24x7. The bulb's replacement cycle was about every 9 months, if I remember correctly. It didn't burn out, but the manufacturer had a recommended useful lifespan documented in their literature. The sterilizer hooked up to a dedicated pump that was tweaked to the manufacturer's recommended flow rates for water born pathogens.

My empirical observations after running UV for a couple years:

1. I did not notice any detriment to the tank health or the health of the inhabitants. I also did not notice a quantifiable improvement, see point #2.
2.  Had the occasional sick fish at the same frequency with and without one.
3.  Brought the water temp up a tad (no big deal).
4. A good, properly sized sterilizer on a larger tank is an electricity hog. Also had a tendency to trip GFIs.
5.  Does nothing for surface growing algae (for obvious reasons)
6. Kept water crystal clear 100% of the time. (As opposed to most of the time in a good, balanced aquarium).

I would imagine it's AOK to use one as a temporary measure to solve a problem. 

Personally, I don't think they are a necessity. But I also have not noticed any harm in using one.

My advice would be if someone is going to use one, make sure it's sized and set up correctly. Otherwise you're just burning money running it.

Edited June 19, 2021 by tolstoy21

[mountaintoppufferkeeper]

I run UV sometimes. If I am running my rack systems as overflow sumps I will usually run 24 watt/70 gph UV and use it to give a small amout of heat to the system combined with the  25 watt water pump the system stays comfortable temperature wise without needing a heater for most of the year up here.

I also am currently running a 24 watt 70 gallon per hour flow UV in my 75gallon with my colony of 6 mekong river puffer while they sort out their pecking order. Im not sure the dwell time is enough to kill all bad things but i feel like it probably isnt hurting anything and likely reducing risks of skin issues from scratches and nips. 

Edited June 19, 2021 by mountaintoppufferkeeper

[Guppysnail]

@FarriisA welcome to the forum. I also run the fluval in-line uvc on my fluval canisters. I’m please with them.