29 replies to this topic

[Anka]

LOL! nice one

[tywonreef]

uv sterilizers are a very useful tool. the most important thing (as mentioned in earlier posts) are correct flow rate & a suitable sized unit. you should always select a unit that is too big for your tank, I recommend about double, the idea being that it can lose some of its impact as the globe fades (this happens in all tubes) it will continue to be effective. When considering flow rate, slower is better, as long as sufficient volume of the tank is passed through. Every time the flow rate is halved, the output of the unit is doubled eg; if a 15w unit can do 99% of harmful micro organisms in 600 litres of water at a flow rate of 1700 lph, then reducing the flow to 850 lph will allow the unit to treat 1200 litres of water. If used correctly a well set up unit will kill 99% of harmful organisms in the tank. They will not impact nitrifying bacteria as this is attached to your filter media & does not pass through the unit. Only organisms that pass through the unit are affected & no sterilization is carried into the tank. There are basically no useful organisms in the water column of our freshwater tanks so uv will not harm your system. Another important point made in earlier posts is the cleanliness of the water passing through, the more dirt, the more 'shadow' the more pathogens that will slip through, so placing it after a good filter is the best way.

Comparing childhood immunity development in people to fish is invalid in my experience, human anatomy/immune system is entirely different. The human body has always had a love affair with bacterias etc & develops immunity easily, I have never known a fish to become immune to a particular infection just because it has had it before. We see many, many more generations of fish produced within a singe human generation, so if immunity from infection was developing, we would be seeing fish that are immune to common infections such as parasites, fungal or protozoan infections. I personally think the opposite is possibly occurring with more & more common fish becoming easily infected (eg; live bearers) & fish becoming less resilient to ich. Even if immunity is the issue, then it should only apply to juvenile fish, the same as immunity development is only really effective in children (many childhood ailments are far more sever in adults as we do not have the ability to deal with them if immunity was not established earlier). My own experience with fish is that the more infections they are exposed to, the weaker they become, a fish that gets white spot once will not be immune to it next time there is an episode, if anything more likely to catch it sooner.

As I stated at the start a uv is a useful tool, this is something designed to assist us by making out lives easier. A superbly managed tank with low stocking levels, perfect water etc. will not really benefit from a uv, but we are not all perfect & this is dream is not always obtainable. With fish that are super sensitive to dissolved organics/bacteria such as discus, a uv is a brilliant addition & I would not keep them without one as maintaining a perfect tank is not possible for me in my current lifestyle. In the shop I had a group of adult discus thrive for a couple of weeks, one day I came in & they were all sulking & dark. We changed the water, dropped the ph, medicated etc. etc. over the next week, but all to no avail. I then noticed that my old uv had stopped working, within 2 hours of replacing it, all these discus were in brilliant colour & feeding well. I think this result speaks for itself (I know if the tank was perfect condition I would not have had the issue in the first place, but this was obviously not the situation). A uv ia also a good means of reducing the amount of harmful medications we use, while they will not stop all fish to fish transfer (any free pathogens that have not passed through the uv can infect another in the tank), they will greatly reduce the overall amount, sometime even allowing the fish to fight off the infection without even needing a medication. If short term immunity development is true in fish, then this would actually increase the immunity.

The reality is that anything that makes fish keeping easier & helps our fish thrive & survive, then it is a good thing.

[Anka]

Great response tyonreef! You helped me make up my mind.

Can I suggest that a mod maybe sticky this? Might be a good point of reference for future noobs like me.

[bigjohnnofish]

sorry anka i dont agree with tywonreefon with all of what was said in regards to fish immunity to certain pathogens and bacteria....

i have only had one whitespot outbreak in 5 years and i never use a uv light... not because i cant afford it - i'd put one on every tank if i believed it necessary to keep fish alive.... i lost 100 b/n or so in a tank that had 200-250 b/n in it..... probably cause i introduced some new blood without quarantining them first... so my own fault really....

my only evidence to back my argument is from friends... one , like myself never uses a uv and another that does use uv... both in melbourne.... and live next door to each other so they receive the same water supply.... friend A (NO UV) has no comebacks with dead fish after they have been bought... friend B (UV) has about 50% death rate after a month on all his fish sold......

too much coincidence i reckon... and more evidence about 6mths ago friend B no longer uses UV and recently has had no deaths after selling fish.....

we are all entitled to our own opinion....

dont let me influence your opinion and if you wish to buy a UV by all means do so... it'll at least make you feel better!!!

[sydad]

Unfortunately the response that tywonreef has provided regarding the immune response of fishes is seriously flawed. There has been a considerable amount written on this subject, including a number of books, with some printed as far back as 40 years ago.These books, and articles appearing in a number of reputable publications, have been written by specialists in the field of immunology, and the one thing that all emphasise is that fishes possess a well developed, if somewhat primitive, immune system that displays the ability to confer active immunity against a number of diseases. There have been, I understand, successful vaccines against several common diseases, but the expense of producing and distributing these precludes their common usage, particularly in aquarium fishes.

As I am not a qualified immunologist (though I do have some experience in medical immunology, although mainly now out of date), I will not attempt to make any detailed explanations on this topic. I will however make one statement with certainty. In almost 60 years of fish-keeping, I have NEVER had the experience of having a repeat infection in any fish that has had white-spot and survived. I grant that this may be a statistical anomaly, but I would point out that in my early years of fish-keeping, white spot was a continual, ongoing problem: not only for myself, but for many aquarists I knew personally, and most of whom had the same experience. In fact I suggest that white-spot is a disease to which many aquarium fish have in fact developed at least a partial immunity. There is evidence that the antigenic properties of some strains of this disease have changed, and that these strains are the ones now seen most commonly.

My earlier comments on UV treatment of aquariums stand.

Syd.

[tywonreef]

Sorry, I should have mentioned that this is paul from morley using tywonreef's account with permission(can't remember mine)

ok, point I was trying to make is that these are a useful tool, just because you are not using a uv does not mean you will have problems, good management is still the most important factor & people have kept fish successfully for many years before we had a lot of modern equipment.
Syd, you may have never had a repeat infection of white spot in a fish, but you are also a very skilled & one of the most experienced & knowledgeable fish keepers in W.A (far exceeding my own knowledge & ability), so no doubt white spot would be a very rare occurrence for you in the first place. People who are less skilled, do not have the ability to quarantine fish or who's lifestyle does not allow the level of husbandry that may be required will definitely benefit from the use of a uv. I have without doubt seen re-infection of white spot, the most obvious cases in my large display aquarium where over 20 years of being established, several outbreaks have occurred. The large clown loaches & decorus catfish which have always been in there have become infected each time. When these outbreaks have occurred the uv was not functioning or required a replacement globe, I have never had a major outbreak where the unit was functioning properly. If immunity to white spot was developed, white spot would not be anywhere near as common as it is as every fish we sell that had previously been infected would then be immune, I can assure you that this is not the case. Quite possibly some immunity to infections over time is occurring, but nothing like the development in humans & certainly not noticeable in the short term, however I am also no immunologist rather relying on my own observations & experience so it is always possible I am completely wrong. The only real proof I would accept that fish will become immune would be the elimination of an infection from the hobby by deliberate, controlled exposure over time - something I have never heard of, but would be a desired practice by all professional breeders if possible (I would personally deliberately infect every fish with white spot & then cure it to make sure none of my customers ever get a dose as we would become the worlds first guaranteed white spot immune fish supply - brilliant).
bigJohnnofish, your friend with the uv loss rate is surprising when compared to other experiences, that is to say that almost every large importer/wholesaler & many large stores with recycling systems use uv's, if this led to increased losses from purchasers then they would stop using them pretty quickly, coincidence is most likely. Possibly some reduced immunity may occur in fry raised in these conditions (as I mentioned the use for fry raising may not be ideal), but this would indicate that the fry being sold are being placed in a tank where an infection is present or they would not need the immunity in the first place, 50% losses from this seems unlikely for the uv use alone.
In a home aquarium, deliberately subjecting our fish to these rigors seems like madness to me, surely providing the best, most pathogen free water is the most sensible approach to a healthy tank & uv's can help to achieve this aim. There would be very few professional outfits around who deal in massive numbers of fish that do not use uv's, they, like myself who constantly have new fish coming & going, have found these to be a fantastic addition which greatly reduce chemical control requirements.

[simmoman]

Thanks very much for the input guys. I think we have enough expert advice.

Peace, love and goodwill to all PCS members. Have a great Christmas.


Peter

Edited by simmoman, 21 December 2011 - 03:26 PM.

[bigjohnnofish]

hi paul.... i agree with you when your a fish re-seller / dealer.... you get everybodies fish coming through your tanks.... with who knows what they are carrying in with them.... so a uv is probably essential for you to prevent deaths....
but in my situation raising fry over time in a system with uv running would be great but im a firm believer these fry have no or little resistance to any pathogens....
pathogens are present in all water.... its just the level of these pathogens that concerns us.... when levels get too high and the fish cannot fight these off on their own is when they become infected...

when you depend on your reputation to sell fish you've bred/raised you cant afford them to have little or no immunity.... it'd be like raising a human in a bubble for 10 years then sending them out into the world full of pathogens (germs) hoping they'll survive...

i think we all agree in what we are saying to some extent - merry xmas / happy new year!

[tywonreef]

Hi Johnno, I do agree with you on this point - there is a possibility that we may affect a developing immune system by using a uv on fry, so it is probably not an ideal situation to use one for this purpose due to the potential of creating weaker specimens. I am not sure if this is valid or not, but the potential risk outweighs the benefits. This would obviously not apply to adults or display aquariums.
Merry Xmas to all at the PCS.

[Anka]

I have no intention to breed at this time - only have a display tank tht I would like to keep thewater crystal clear and the fish healthy.