FAQs on Ultraviolet Sterilizers for Freshwater Aquarium Filtration

FAQs on Ultraviolet Sterilizers for Freshwater Aquarium Filtration

Sterilizers and (wound healing of) Aggressive Fish 9/2/15
I have read all of the WWM FAQs on UV sterilizers and I understand that there is no consensus on their general usefulness.
<Oh! IMO/E they are of real value>
One of the issues I did not see expounded upon was whether or not a sterilizer has any noticeable effect in reducing the rate of infection in wounds which may be more common when keeping aggressive species like cichlids.
<I have high confidence that this is the case>
Is there good reason to believe that running a sterilizer would be useful in such a situation?
<Yes; UV use, ozone production.... raises DO, reduces TBC, elevates RedOx...>
Thanks.
-Andy
<Bob Fenner>

UV Sterilizer, FW use 4/29/12
Hi Crew,
I'm looking for your opinion regarding the usefulness of a UV Sterilizer on a 240 gallon freshwater Discus aquarium for the purpose of parasite, algae and disease control. And if you support the use of one, what size (watt) and gph would be required?
Thank you,
Pat
<Hi Pat. UV in freshwater tanks is useful but not a cure-all. Furthermore, it's most cost-effective for retailers and wholesalers who need to minimise parasite cross-contamination between successive batches of fish. In a single aquarium you'll kill off parasites when they appear, and in theory, until you add something new, that's the last you'll see of Whitespot or whatever. It's important to understand UV only kills parasites or algal cells that flow through the UV steriliser. It has no impact at all on algae in the aquarium or parasites swimming about in the tank. So while Whitespot for example brought in on a new fish is less likely to contaminate existing fish, it isn't a 100% prevention. If you have money on hand and don't care
about the running costs (regular cleaning, new UV tube each year) then by all means add a UV steriliser, and some problems, like diatom blooms in the water column, should reduce or vanish. But as a general addition to a freshwater aquarium, you'd be better spending the money in other ways.
Cheers, Neale.>

UV TurboTwist 3x and Fluval 404... FW filtr., alg. contr. - 1/24/08 Great site, very helpful! I've got a 55 gallon tank with two Aquaclear 50, each with a small piece of foam, and then filled with carbon. A Fluval 404, bottom two sections foam, top two Bio-max. <Hmm... I tend to consider carbon a waste of time in freshwater tanks. Here's my pop-quiz for you: what does carbon do that water changes don't do better? Bzzz... Nothing! Carbon in Old School fishkeeping from back when people avoided water changes, doing 25% per month or even less. Carbon removed the organics from the water, stopping it go yellow. Since we now do big water changes every week, the organics never reach a concentration where they cause problems to freshwater fish, so the carbon is redundant.> It's a healthy tank, with 9 Discus, from 2" to 4". Two Cory cats, a small Pleco, and a tiretrack eel. I've added a Coralife Turbo-Twist 3x (9 watt) mostly for green water algae. <Green Water is not normally a problem in freshwater tanks. It's more a pond issue. UV filters have next to now effect on things like hair algae or the diatoms that cover the glass. Healthy plants are a far better way to deal with algae, to be honest.> Can I still run my Fluval at full blast? If I have to slow down the flow for the UV, how will that affect my biological filtration? <It's a Catch-22. If the water is pumped too quickly through a UV steriliser, the microbes aren't all killed. But canister filters need rapid water flow to keep the oxygen supply inside the canister adequate for the needs of the bacteria. Realistically, I'd always favour filtration above UV; I'd sooner have 100% biological filtration capacity but only 50% UV efficiency than the other way around. UV is undoubtedly useful in marine tanks, but in freshwater systems it's a luxury, so there's no need to squeeze out every drop of performance from the contraption. Regular water changes, rapid plant growth under strong lighting, and control of nitrate and phosphate levels will have a dramatically greater impact on fish health and algae control.> Thanks, Joe <Cheers, Neale.>

Freshwater Ich and UV Sterilizer 12/25/07 Thank you so much for being here and available. I've done many searches on your site over the past few months an have learned an incredible amount. Now I have a problem and would like advice. <Okeley dokely.> I have been back in the hobby since last April, after some years away. This time I've been very scientific, reading and studying and actually understanding the why as well as the what. I currently have a 10 gallon non-CO2 planted tank (set up last May) and 10 gallon mixed reef (set up last August), both very successful and I am setting up a 46 gallon planted tank. The big tank is my problem. <Hmm...?> OK, I took a chance and screwed it up. I cycled the tank with mulm from my old tank, and the levels dropped very quickly. I stocked it with fish from one, usually very good, LFS. Cardinals, cories, hatchet fish, pearl gouramis, cherry barbs, 6 very expensive guppies from a breeder in California. I figured I'd stock it very quickly and then stop, no more fish or anything, and I'd be great. <Mulm doesn't really carry a huge amount of filter bacteria: bacteria are mostly where there's rapid water flow, because they're super-demanding of oxygen. Gravel from a tank with an undergravel filter is excellent, but otherwise old sponges from a mature aquarium are best.> A couple of the hatchet fish developed ich after about 6 days in the tank. I noticed a spot last Wednesday, hoped against hope it would be nothing. It spread to other fish. Last Friday morning it was apparent I had a serious emergency. I have no way to quarantine 30 fish. I'm going to be out of town the first week of January. <Hatchets are very sensitive fish at the best of times, and I'd not add them to an immature tank, no matter how "cycled" I thought it was. In any case, Whitespot shouldn't be deadly in the very short term, and adding suitable medication should at least slow things down, even if you're able to do all the doses required to kill the infection.> I had a major panic attack, did some research on-line and started calling around town. One LFS "could probably get me a UV sterilizer by next Thursday." The other LFS had one they recommend in stock. (I've dealt with both stores before, they're both pretty good.) After discussing install options, I bought an inline UV sterilizer, a sump, and a pressurized CO2 setup as well. I figured since he was coming out anyway, we'd do everything I'd been thinking about. We had it installed by 5pm last Friday. <UV filters don't 100% kill Whitespot (or any other type of waterborne parasite). They certainly help, but wouldn't be my first line of attack. Elevating the temperature plus adding salt, or treating with anti-Whitespot, would be better.> I bought some Ich treatment that he recommended, just in case, but I really don't like dumping chemicals in the tank if I don't have to. I was hoping the sterilizer would handle it. <Nope.> http://www.uskoi.com/ich-x.htm The hatchet fish started showing multiple spots Saturday evening. The cardinals have some spots, the gouramis have some spots. Nobody was in great discomfort. This morning (Monday) the (VERY expensive) guppies aren't showing any spots that I can see but the girls are hanging out on the top a lot more than they have been since the arrived last week. :-( <Whitespot irritates the gills, and over time leads to something akin to suffocation.> To recap - I bought the hatchet fish a week ago Saturday. I saw my first speck Wed afternoon. Friday afternoon the hatchet fish had several spots and I had an obvious problem. We installed the UV filter Friday by 5pm, and turned the flow down on the pump as low as we could get it. There is flow but quite minimal. (Recommended to kill parasites.) <Sounds an odd recommendation. Most UV filters I've seen added to tanks use normal water flow from an external filter or whatever. Is this a separate pump just for the UV device?> I keep the tank temp set at 78F, I noticed this morning that it's at 80F. Possibly because I keep the room very warm. The CO2 is one during daylight hours. I do not believe it is gassing the fish out, in fact I may turn it up a bit when & if I solve the Ich problem. The plants are pearling nicely. <There is a balance that needs to be struck between the CO2 the plants want and the stress high CO2 levels cause fish. But that's unlikely the issue right now.> I did a 15 gallon water change yesterday afternoon (Sunday). I am assuming the spots that are showing up now are parasites that were already attached on Friday. I am assuming that the UV filter is going to drastically reduce the free-floating stage and I should start seeing a reduction soon. I can do another water change this afternoon, and probably another one tomorrow. I have to pack all my water from town, my well is too salty for plants or fish. <The feeding stages on the fish will need to mature and hatch before the UV filter can do anything. Warm water speeds this up.> But I'm worried. <huge sigh> I'm really stressing out. :-( <Not much you can right now beyond treating the tank. I'd not hold much store by UV alone at all, though I'm open to correction here.> Am I on the right track here, with the UV sterilizer? When should I start dumping chemicals, or should I at all? What chemicals? I'm freaking out this morning because the female guppies are looking a bit too quiet. (The males are being typical guys. <g>) What type of time-line should I expect with this blasted parasite? <The life cycle of Whitespot is 2-3 days at tropical temperatures, so in theory you should see improvement quite quickly.> SueP <Cheers, Neale.>

Re: Freshwater Ich and UV Sterilizer 12/25/07 Thanks! <You're welcome.> OK, I'll do another water change this evening & add the meds. I understand that salt will kill the plants? Should I turn the temp up? <Salt at the doses required to treat Ick will not harm your plants; nor will elevating the temperature.> The UV sterilizer is in-line with the canister filter. Both are large enough to handle the tank. The sterilizer suggests doing 2 tank turnovers an hour for parasites. Higher flow will kill algae but they want the water to spend time next to the light to kill parasites. <Ah, that does make some sense. But my worry here would be reducing the water flow through the canister filter. Canister filters have HUGE oxygen demands, and slow water flow switches the highly aerobic bio-filtration bacteria into a dormant mode, which you obviously don't want. I'd personally prefer better water quality with less effective UV filtration than the other way around. UV is "icing on the cake", but water quality is the essential "meat-and-potatoes" of fishkeeping (if I can mix my metaphors!). Cheers, Neale.>

Re: Freshwater Ich and UV Sterilizer 12/25/07 Update - I just dumped 4 tsps of Ich-X in the tank. I'll do a water change tonight and treat again if things look worse. <Hmm... don't do water changes while treating -- for hopefully obvious reasons, if you suddenly dilute the concentration of medication, the medication will lose its efficacy. So hold off water changes until your have completed the ENTIRE course of medication, which may be multiple doses across several days.> And I did add the filter media from the old tank as well, when I started this one. We tested and the cycle seems to have completed within a week. I hope the meds don't mess it up now, but I'm more worried about the fish. <No, modern fish medications are almost universally safe with filter bacteria.> FWIW - the guppies look a bit better and the female Gourami was offering to lay on her side and breed a few minutes ago. <Very good. Cheers, Neale.>

Re: Freshwater Ich and UV Sterilizer 12/25/07 The Ich medicine bottle suggests doing a 30% water change just before every dose. I assume it's to remove as many free-swimming parasites as possible. Realistically, I'm not able to do the water changes that often. <Hmm... regardless of the reason, always follow PRECISELY the instructions on the packaging. Failure to do this can lead to a variety of problems, including failure to adequately treat the disease.> Today I had the water but it's taking forever and ever for my heater to get it up to temp, so I just dumped the meds in the tank and left the new water heating. I may use it tomorrow, but esp. after hearing your opinion, I may let it go another day or two dosing without water changes. <Provided you use water conditioners, there's no harm in using a mix of hot and cold water to get the warmish water you need.> I'll turn the flow up on the canister filter when I change the water and can tell how hard it's moving. <OK.> I still have a few visible Ich spots but everybody seems comfortable and active. Occasional flashing but not constant. <Good. Do remember the medication stops re-infection, it has no effect on the current (visible) generation of white spot parasites.> The female Gourami has a ding on her side but I suspect she banged a scale when she was being chased by the male. I'm watching it, I'm feeling rather paranoid at the moment <wry g>, but so doesn't look in distress and it doesn't look fuzzy or anything. <Are these Dwarf Gouramis (Colisa lalia)? These are very commonly infected with a viral disease that is untreatable and highly infectious. An early symptom is small blisters on the body. Infected fish should be painlessly destroyed and Dwarf Gouramis never, ever added to the tank unless it is autoclaved. I'm not kidding about this... as far as I'm concerned, people shouldn't buy this species unless they got them from a local breeder.> Thank you so much for your help! Hope you had/have a really wonderful Christmas! <Thanks, Christmas was swell. All the best, Neale.>

Re: Freshwater Ich and UV Sterilizer 12/26/07 No these are Pearl Gouramis. I didn't know that about Dwarfs, what a shame. And I've been admiring them for months, wanting to buy a pair. Guess I won't... :-( <Pearl Gouramis are excellent fish; generally peaceful, long-lived (7+ years) and hardy. Dwarf Gouramis are a total waste of time/money.> Did a 15 gallon water change at noon today and added the third dose of meds. Everybody looks good, the hatchet fish still have a few spots but the visible spots are definitely clearing upon everybody else. <Sounds good.> One of the guppies is having babies, I hope they make it to the thick plants. Nobody in the tank looks particularly voracious, and historically I've had more problems with overpopulation than with babies surviving. But these are pretty special guppies, so I'm hoping! :-) <Hatchet fish will eat them given the chance, but as you have lots of plants, you might luck out. By all means confine the babies to a floating breeding trap for a few weeks if you want.> I turned the flow on the filter up and the guppies are surfing the current. :-) <Ha! Sounds as if you have everything in hand. Cheers, Neale.>

UV-H13, pump, set-up 10/12/07 I recently bought a 9 watt UV-H13 sterilizer. What type of pump do I need to get for it? I have a 75 gallon aquarium. Help!! Thank You Erin <Erin, typically these devices are connected to the *outflow* of water from a canister filter. The idea is the canister filter removes silt from the water, and the resulting clear water passes through the UV steriliser, where the algae and bacteria are (hopefully) killed. If water is pumped straight from the tank through the UV steriliser, the penetration of UV light is limited by the silt in the water, and the algae and bacteria are less effectively killed. Hope this helps, Neale>

Re: UV-H13 10/12/07 Can I get a canister filter at a local pet store. I, unfortunately, don't know a lot about aquariums....I just have a love for them. I also have a local fish store. Maybe I should try there? <Yes, you can get external canister filters from most aquarium stores. There are many different brands and models. The main thing is that the outflow hose on the filter fits the UV filter you have. Typically, the hose will have either a 12 mm or 14 mm diameter. Check the diameter of the nozzles on the UV steriliser. Then, make sure you buy a compatible filter. Most small UV sterilisers seem to use 12 mm fittings, and that should be compatible with any small canister filter. The last time I set one of these UV sterilisers, the procedure was very simple. All I did was close all the taps to stop water sloshing everywhere; (over a bucket) cut the outlet hose from the canister filter in two; insert the two free ends so produced into the UV steriliser; and then after checking all the connections were watertight, open up the taps and turn the filter back on. Entire process took ten minutes, if that. I'm assuming the UV-H13 unit you have comes with taps and seals for connecting the hoses to the nozzles. To be honest, UV sterilisers aren't critically important in freshwater tanks, though they can be useful. If I was advising a total newbie on the hobby, there'd be other bits of equipment I'd have them worry about first. A canister filter is, funnily enough, a very useful thing, and you'll probably (certainly) get more profit from that than the UV device! Cheers, Neale>

Re: UV-H13 -- 11/13/07 Well, my aquarium store suggested I get a uv sterilizer b/c I'm having a terrible time with green water (i.e. algae). I bought a sterilizer in the past and it totally resolved the problem. But it recently took it's last breath. We made it for about 3 months without it. Then the algae came back. So here we are again....I will take a second look at my new sterilizer and I will also take it to the aquarium store with me so they can get me hooked up and running. Thanks so much for all your advice. I appreciate you taking the time to help me out!! Have a wonderful weekend! <Ah, makes sense now. Yes, a UV sterilising should help with green water. Now, did you consider simply changing the UV bulb rather than the entire unit? Anyway, good luck! Neale>

Re: UV-H13 10/15/07 Yes, we did try just having the bulb changed but the people at the aquarium store said that when they opened the unit up, it cracked or something. Anyway, whatever happened, they were unable to repair it. I wasn't really happy with the way the whole thing happened. Oh well. We got our NEW one set up and running over the weekend! Hopefully it will do the trick. We just got it done Sunday afternoon!!!! We shall see! <Your retailer broke it? Bizarre. Normally, these things are designed so the UV tube is easy to replace. That's the whole idea, because the tubes only last ~12 months. Make sure you keep the instruction sheet, and then when it's time to replace the UV tube, you'd perhaps be safer doing it yourself. Cheers, Neale.>

UV sterilizers, New world Cichlid Companions 8/16/07 Hi Crew, <Hello,> i would like to ask your opinion on the following questions. <OK.> 1) I am living in a very hot climate (Greece) and as a result every summer my fish suffer from excessive heat. Aerating the water and doing partial water changes with cold water do not seem to help, as the water quickly rises to 33 degrees Celsius after every water change. As far as i am aware, hot water increases the chances of bacterial infections. <No, these things aren't really connected. In fact, with most tropical fish, it's the reverse: cold conditions cause infections. What too-hot water will do is reduce the concentration of oxygen, and it is THAT which stresses the fish and allows them to get sick more easily. Increasing the aeration in an very warm tank helps here.> So i was thinking of 2 ways of dealing with the problem. I) I could add a water chiller or II) i could add a UV sterilizer to control bacterial spores. <The first solution would work well, but would be expensive. The second solution would not work at all. UV sterilisation helps, yes, but if the conditions are fundamentally dangerous for the fish, the fish will get sick anyway. You can't possibly remove all the bacteria from the water.> As far as i know, water chillers are much more expensive than UV sterilizers. <Yes and no. Commercial chillers are expensive. But DIY versions are not. For these, all you need is an old fridge. The "mini-bar" kind work great. Drill a couple of holes in the thing, and then wind a few metres of hose through it. Connect one end to a filter pump (e.g., the outflow from a canister filter) and stick the other end in the aquarium. A cheap and cheerful chiller! An even cheaper solution is this: ice. Get a couple of 1- or 2-litre ice cream tubs, the plastic kind. Clean and fill with water. Put the lid on. Freeze. When the water gets too hot (over 30C) put one of these in the aquarium. Over the next few hours it will thaw, drawing heat from the aquarium. When it has melted, put it in the freezer, and replace with the other tub. Repeat as required. While not a perfect solution, this system is very effective if the "hot season" is only a few weeks in summer. It also has the virtue of being very cheap!> So, taking into account the fact that i do not keep overly sensitive fish (my 100L tank is stocked with Firemouths and a Glyptoperichthys Joselimaianus), i think that the addition of a UV sterilizer is a better investment. If you agree on this, i would like to ask the preferred design-specifications of a UV sterilizer appropriate for a 100 L tank. (power, high-low pressure, flow rate etc) <I wouldn't bother. Far far better to cool down the tank, increase evaporation (which also cools down the tank), and increase the aeration. Alternatively, choose species tolerant of very warm water. Discus, clown loaches, gouramis, angelfish, Apistogramma, etc. are all fish that thrive in water around 30C. On the other hand, avoid anything borderline tropical or subtropical, like peppered/bronze Corydoras, Danios, many barbs, some tetras, etc.> 2) Currently the tank is stocked only with a Leopard Pleco, but i am planning to add a Firemouth soon. I was also thinking of adding a Blue Acara (Aequidens Pulcher) and i would like to ask your opinion on the compatibility of these 2 species. From my experience adding two (or more) male Firemouths in the tank is a pure disaster (i have tried to keep 4 of them in the same tank but they were overly aggressive). I know that cichlids tend to be particularly aggressive towards conspecifics, so my thought is that if i added an Acara, i could be able to keep their aggression under control. <I personally wouldn't mix South American and Central American cichlids. There are certainly exceptions of course, but in general Central Americans tend to be more territorial and a lot more aggressive than South Americans. To some degree, this all depends on aquarium space. In a 100 litre tank, my guess is you have NO chance of getting these fish to coexist. An adult male Firemouth cichlids will simply view the entire tank as its territory. Even in a 200 litre tank, I doubt it would work out. Personally, I'd look for something in the "dwarf cichlid" market if you want multiple species. This would also leave you space to add midwater fish. On the other hand, you might try looking at some of the unusual Anabantoidea instead of the cichlids. Climbing perch (Anabas, Ctenopoma, and Microctenopoma) include some superb species most of which are very tolerant of warm water because they can breathe air.> I am looking forward to hear your comments. Thank you in advance Spyros <I hope this helps, Neale>

UV filtration with 2 filters, and parasitic FW sys. f' 7/26/07 Hello again! I'm the one who recently asked about treating a 130g tank that had gone through a nasty outbreak of Chilodonella, before reintroducing the then cured fishes. I followed the advice I received, and treated with Malachite green/formalin for a few days, coupled with massive water changes. I cycled the tank, and have since successfully transferred all afflicted fishes back (and some more) and so far, everyone is doing very well. No signs of ill-health at all. Thanks again for the advice! <Congrats!> My question this time has to do with the set up itself, especially filtration. The tank is 72 x 24 x 16 inches and filtration is provided by an Eheim Pro II 2028. I've come to realise that I'm probably under filtering: the Eheim is rated for 277 GPH, which I hear corresponds to the flow-rate without any media in the box. This means that in actual practice I'm probably getting my volume turned over at most 1.5x an hour. <Yes> So I figured I probably should get another filter, and in any case, it certainly can't hurt. Wouldn't you agree? <I do> I'm especially leaning towards the Filstar XP4, since I can get one on sale for rather cheap. Flow rate seems a bit high to me (450GPH), but I suppose with a spray bar turned in towards the glass, the fishes (Severums, Geophagus and jack Dempseys) wouldn't mind the flow. <Not at all> Now, I also wanted to add a turbo-twist (Coralife) UV steriliser, but was wondering what the most efficient way to set it up would be. Does it make a difference which filter I mount the lamp on? <In this case... not really... both will/would provide adequate circulation... both magnetic driven pumps will be about the same mal-influenced...> I figured the one with the higher flow rate would be preferable, since the water would get to meet the light more often. <Mmm... oh, I see you address this below> So, I figured the best option would be to get the 36W model, for flow-rates between 400 and a 1000 GPH, and mount it on the Filstar. <Yes... these would be well-matched> Then again, I was worried that once loaded with media, the actual performance of the filter could fall below this. <You are correct> How damaging would that be in practice? <Mmm, not enough to be overly concerned> Would I be better off getting the lower powered lamp (18W) and reducing the flow-rate to below 400GPH? <Yes... IMO this would be fine> That would put me on the higher-end of the scale and, I fear, would reduce efficiency due to decreased exposition time. What would you recommend I do? <I'd go with the 18 watt unit... and hook it up to the new filter> I'll set up the filter first, to test the actual flow rate, but should I find it to be below 400GPH, which of the two filters should I mount the lamp on? Ideally, I'd have one on each but, well, one's funds are never unlimited... Thanks again for this truly wonderful service you are providing. Best, Eric <Welcome! Bob Fenner>

Filtration questions; do I need a UV sterilizer? 2/16/07 Hey - <Hola> My name is Patrick... <Patrick> and i... <I...don't want to nit-pick, but please understand I have to re-type all these improper uses of punctuation so that we can organize the queries on our website...> ...had some questions about my filter setup. <Go for it!> I have a Cascade 700 and a BioWheel 350; I am starting my second 55 gallon tank. Will those two filters together work well or should I add a biological filter like a sponge? <Each type of filtration has its proper place in the hobby - what is your tank stocked with (or what will it be stocked with)? For my purposes, which include freshwater community tanks, power filters with BioWheels have served me well, but I do add an additional filter media called "PolyFilter" to help keep phosphate levels in check. It's hard for me to give you a full answer without knowing more about your setup, but generally speaking, power filters are an easy and efficient way to keep a standard community freshwater tank healthy. For notoriously messy fish, like goldfish or puffer fish, you can help combat their "messiness" by adding a second power filter unit, but under most circumstances, this isn't necessary...> Also my local store suggested a UV sterilizer to help with preventing algae and other harmful pathogens. <A UV sterilizer will not combat algae, but rather a combination of water changes, controlling phosphates, not having excess lighting, and not feeding too much will help with this issue. With regard to harmful pathogens, be aware that EVERY fish tank has some level of pathogens in it, but when regular water changes are done and the livestock is kept in stable, proper conditions, their immune systems should be strong enough to not allow them to succumb to the "nasties". The jury's out on the use of UV sterilizers in general - some folks swear by them, others think they do way more harm then good. The "general" consensus seems to be that if you keep up with regular water changes, have good filtration, and use a quarantine tank for all new fish acquisition (and a hospital tank for all sick fish, should the need arise), that will suffice. Here's a nice article summarizing the use of UV sterilizers in aquaria - http://www.fishlore.com/uv_sterilizer.htm > Would I need one or would my combo of filters be enough? <Again, without knowing specifically what you intend to keep, I can't say for certain. However, provided that you practice good husbandry on the tank(s) in question, you will likely be OK without using a UV sterilizer.> Patrick <Best regards, Jorie>

FW UV use, algae impact - 12/06/06 Hi. <Greetings to you! Michelle here.> I understand that UV will kill free floating algae. <Yes.> I assume that if I have algae already growing on my rocks, the UV will not hinder it. Would this be correct? <This is true.> I have Tropheus that graze, so I don't want to cut down algae growth on the rocks. <No need to worry.> Thank you for your assistance. <You are welcome. -Mich>

Use of UV Sterilizer on Molly Fry tank Hi all, I was thinking about using a UV Sterilizer for a Black Molly rearing tank. My reasoning is that it would be an extra form of protection for the fry considering how delicate & susceptible to disease they are. What do you think? Good or bad idea? <Would help, wouldn't hurt> Also how is a UV Sterilizer connected? Does it run independently or does it have to be attached to a filter or something? Thanks. The MollyMan <Needs a fluid-moving source and electricity. Please see here re: http://www.wetwebmedia.com/UVFAQs.htm and the linked files above. Bob Fenner>

UV sterilizer in a freshwater tank 09/13/2005 First off, I want to say that the site is unparalleled in the amount of information available. Many heartfelt thanks to all the hard working people at WWM for their selfless expenditure of time and energy to make this site as awesome as it is. Without trying to be too long winded (I am Italian, I talk with my hands and I am typing <g>) I will explain my situation and questions. My new wife has had aquariums for about 20 years and she got me interested in the past year or so. We are working diligently to become more conscientious Aquarists and this site has been a big help in the past couple of months. <Ah, good> Right now we have 3 tanks up and running, 2 work in progress tanks, 1 QT/hospital tank and looking down the road to Saltwater, and it is our 150g community tank that I have an issue with and need advice. It is an All Glass MegaFlow tank that has 2 MegaFlow chambers leading to the sump. The tank is well established, being up for about 6 months, but all the inhabitants and the wet/dry filter were in a 125g for almost a year and all, including water were moved into the 150g because our LFS made us a deal that we couldn't refuse. The inhabitants are as follows: 2 African Butterfly fish (they eat out of our hands, it's great), 9 assorted Gouramis (from True Gouramis to Blue Paradise), 3 assorted Angels, 3 Swords, 7 Zebra and 3 Giant Danios, 4 Tinfoil Barbs, 2 Rainbow Sharks, 1 black Ghost Knife, 2 Dojo Loaches, 1 Peacock Eel, 1 common and 1 clown Pleco and 2 CAEs. By the way, they all do play together very well and we have a very active, layered tank that has received many compliments as it is the showpiece in our Living Room. Now to the crux of the situation: We have an ongoing issue of suspended particulate matter. To try to deal with this, we have cut back on our feeding. We realized that we were overfeeding when we had a nitrate reading almost off the chart and we are using Nitra-Zorb in the sump along with extra water changes (we normally do 20% every 2 weeks) to combat this. I admit we were lazy and just used to get the water tested once in a while at the LFS instead if having a test kit (we have a comprehensive kit now), we had the water tested this past Saturday and that is how we found out about the nitrate issue. The rest of the water parameters are good; PH is 7.2, Ammonia 0 and Nitrite 0. We also switched to sand as a substrate instead of the detritus trapping gravel and are using a 100 micron pad with a carbon pad in the drip tray of the w/d but we can't completely eliminate the suspension. Our LFS recommended using a UV sterilizer as they think the suspension is organic in nature and that the sterilizer would eliminate it. <Might... a worthwhile addition in any case> I have read the FAQs but I can't seem to get a definitive answer for my situation. I am more inclined to use a canister filter with diatom powder or a regular diatom filter for the water polishing as needed since we have so many tanks up/planned and I am hoping you can clear the haze of cobwebs. <Also a good tool... for periodic use...> If the sterilizer is the better way to go, where is the best placement for it? <The final item in your return line from an outside pump...> In the sump or on the back of the tank as the drainage to the sump is gravity and the water is only stirred up by the 2 outflow tubes. <The back of the tank> Additionally, what would you recommend as a good waste eater for the tank, we can move out some of our 'children' to the other tanks to make room. <A grouping of a species or two of Callichthyid catfishes... Larger Corydoras or Diadema, or...> Once again I thank you for your patience to get through this email. I hope that everyone at WWM has a good a day as I have every day. Tom <Thank you for sharing your experiences, enthusiasm. Bob Fenner>

UV STERILIZER and FW disease Hi Bob. Have a problem and need a little advice as it involves more than just changing water. :) <Okay> My largest tank, a 55, right now has 3 Big Spot Plec's (all around 5 inches), 1 Bristlenose at 4", 4 Cory sterbai and about 15 smaller dither fish. (Do I need to state my readings? OK. 0,0,15. I do lots of water changes!) <You know you and I like those> I keep losing the dithers with the bent spine of fish TB. Couple of Zebra Danios, a few White Clouds, one Cardinal Tetra. I also have 6 Rosey Barbs (2M, 4F) in there. The female Rosey have looked like they're gravid since I got them 8 months ago. Now all the females are starting to show the bent spine. The males both look normal and healthy. <... not good... can be a few things... I'm fearful it's Myxosoma, not nutritional, environmental... given the fact that the cats appear unaffected. Are you familiar with whirling disease?> I know I should break down the tank, put down all the fish and start over, but frankly with my prize Big Spots in there it's just not going to happen. In speaking with Sabrina about this she mentioned she knows of no report of catfish getting TB. (Can you add anything to this?) So the plan is to put down all the dithers, healthy looking or not, and add a UV Sterilizer. <Siluiiforms can indeed "get", perish from Mycobacterial infections... but these would be long gone by now if this were the causative agent.> Does this seem like a good plan of attack to you? My thoughts are that the catfish, being bottom dwelling, mud sucking scavengers have been provided one hell of an immune system. Nature is good that way. By ridding the tank of the reservoir of infection in the dithers and running the UV I hope to clear the bacteria. <Maybe... do you have any such problems with similar groups (Cypriniiform/minnows) in other of your systems... using the same water?> Right now I have two tanks running. The 55 and a 10 with my breeding Bristlenose. I have 35 two week old fry in the 10 right now along with the parents. So I have to do something soon. Plan is to get a 29 and/or 20 and set up the Big Spots for a breeding attempt. Then use the 55 as the grow out tank. Would greatly prefer not to have to break it all down and recycle, but must have a healthy, cycled tank for all these fry. So I'm leaning towards the Sterilizer. <I am not such a big fan of UV's for home, even breeding systems. Not that much to gain. If bacterial in origin, the microbes will be passed in the system by the fishes eating other dead, dying fishes> If you think I'm on the right track, can you recommend a brand, size. I think the 55 is the biggest tank I'll have. Would also want it to be able to go on a 20. The dream tank of Zebra Plecos would be next after getting the Big Spots settled in a 29. Can't/won't even think about the Zebras until I'm sure I'm healthy, tank wise. Don <If it were me, I'd spend the money on another or larger tank, another trashcan/carboy to store pre-mixed water, or a reverse osmosis unit for making water, and hope that if this is indeed a biological vector, that its virulence dies out. Bob Fenner>

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