How Effective are UV Sterilizers

How Effective are UV Sterilizers?

Every week we do our best to help you guys, members of the reefing community enjoy your tanks and find new ways to explore the hobby. We do that by following the set up and progression of this one hundred and sixty gallon reef tank.

This week we are going to talk UV sterilizers. We will discuss what they do and don’t do, setting realistic expectations, how they function, how to size and properly set up a sterilizer, answer some common questions and show you the installation for the BRS160. UV sterilizers are probably one of the most hotly debated topics in the hobby with reefers firmly divided in their position of UV sterilizer’s effectiveness in closed systems like a reef aquarium. Sterilizers are designed to protect your fish against harmful waterborne pathogens like bacteria, protozoa and viruses. In a closed system like a fish tank these pathogens can spread quickly and easily wipe out the entire tank population. UV sterilizers can also reduce the spread of waterborne algae and cyanobacteria which is obviously a desirable effect in the reef tank.

So where does all the hotly contested debate come from? I think it’s mostly from a complete misunderstanding of the expectations of what a sterilizer is going to achieve in a reef tank. The sterilizer is only designed to reduce the chances of an outbreak and in the event of an outbreak slow the progression so you have time to research and treat your fish before they are all affected. The sterilizer is in no way even close to complete protection from an outbreak and of almost no value treating an already existing disease, algae or cyan outbreak. Once the bacteria, protozoa or virus has settled on the fish, defeated its immune system or natural resistance the sterilizer is going to do nothing to protect that fish from the progression of the disease. However it will help protect rest of the fish in your tank. Again in no way can you consider the sterilizer to be an impenetrable solution that completely protects the other fish in the tank but installed correctly it is absolutely reducing the population of pathogens in the tank and give the rest of the tanks inhabitants natural resistance to this disease a fighting chance as well as providing you time to properly treat the tank before the outbreak gets out of hand and you lose the entire tank.

I like to think of this as being trapped in a small room with ten people and one has the flu. If we did nothing there is a small chance all of our immune systems are strong and healthy enough that none of us get sick but it’s more likely it would spread and overwhelm all of our immune systems and everyone would end up sick. Anyone who has got stick after being on a plane should understand this concept pretty well. However If we properly sterilized the surfaces in this room and the air we are breathing the chances of the virus spreading absolutely go down. Even more so if we have the time to spot the sick member of the room and remove them before the rest of us show signs of illness. However even then we can all get sick. Removing the sick member and sterilizing the room and air is far from a sure thing. The goal in the reef tank is not to completely illuminate the chances of an outbreak of disease or algae in the aquarium and certainly not to cure it after it has already happened. The UV sterilizer is simply there to reduce the chances that you ever have to deal with an issue like this and if you do give you more time to do something about it.

Regardless of the side of the debate you find yourself on this is a statement that almost everyone can agree with. There is an endless amount of zoos, public aquariums, aquaculture facilities and marine wholesalers that are in the business of protecting their fish and they use UV sterilizers precisely for this reason. To protect the fish and keep them healthy. These are industries where losing animals just isn’t an option and survivability equals profitability. The Emperor Aquatics brand of sterilizers in particular is popular in these in critical industries. With a pretty long list of respected clients. The one important component you should get from this for sure is a UV sterilizer is in no way a requirement for a successful reef tank. It is really just another optional component of redundancy we can install on the tank to help protect it for the long haul. So now that we have decent understanding of what to expect from UV how does it work?

UV sterilizers do exactly what the name suggests. It doesn’t outright kill the pathogens but instead it uses ultraviolet light to damage the pathogen’s DNA, effectively sterilizing them and preventing them from reproducing themselves. Most sterilizers are fairly simple designs with some larger pipe, a waterproof quartz sleeve and a UV emitting light bulb. By flowing water through the pipe we have the time for UV light to encounter the pathogens and effectively sterilize them. There are three main elements which control the effectiveness of the sterilizer. Strength of bulb, flow rate or contact time with the bulb and size of the tank or water volume the sterilizer has to effectively treat. In most causes a UV sterilizer has to be fairly large to be effective which is an obvious deterrent to most reefers. Not everyone has a few hundred bucks and the space for a few foot long two or three inch pipe. In my option this is one of those things where you are also better off skipping it entirely than installing something too small because an undersized sterilizer is probably a complete waste of time and money.

This is another element which I believe also fuels the UV sterilizer debate. Almost all of the sterilizers marketed to the hobby end of the aquarium market are inappropriately small and fairly useless. Most of the manufactures know hobbyists are more likely to buy small, easy to install and budget friendly options so sadly that’s what they produce and sell regardless of their effectiveness. These tiny sterilizers have almost no value. That’s why typically we look to more industrial options like the sterilizers from emperor aquatics. To maintain a long term successful brand with products popular in commercial applications like zoos, public aquariums and marine wholesalers the products need work as intended and produce profitable results. Working as intended is about creating the proper contact time with the bulb and ultraviolet light sufficient to sterilize the tank. It’s a balance of how much water the sterilizer can hold, how fast you flow water though the sterilizer and the intensity and spectrum of the ultraviolet light. To give you an idea of how these things work in correlation to each other we have three very similar wattage sterilizers here.

Forty watt Emperor Aquatics lite which uses two inch reaction chamber. a forty watt standard which uses a three inch chamber and a fifty watt high output which uses a five inch reaction chamber. The standard forty watt sterilizer with the three inch chamber is good for a tank up to two hundred and sixty gallons with a recommended flow rate of a hundred and fifty seven gallons an hour to properly treat for bacteria, algae and protozoa which cover pretty a vast majority of what we are concerned about. However that three inch chamber is pretty large and can be hard to place and why they make the smaller two inch lite versions. Even though bulb is the same strength the smaller reaction chamber reduces the dwell time and exposure to the UV light so the light version is only good for a tank up to one hundred and sixty gallons rather than two hundred and sixty gallons. The suggested flow rate is also significantly lower at nighty eight gallons. The high output fifty watt version is just ten watts more but it is good all the way up to for hundred and eighty gallons . This is because the higher intensity bulb can penetrate the water further within the five inch chamber which also has additional dwell time. Suggested flow rate is two hundred and sixty gallons and hour. I would note that while it is bigger around it is only 30 inches long where the light and standard forty watt sterilizers are forty three inches so the high output models might be the best fit in some instances just because of the shorter body style.

Couple things you should note about these suggestions. You will notice that ratings are significantly lower than most of the products out there. That’s because it is important to them that the products are effective. The flow rates consider about 90% UV transmissibility knowing your water is likely somewhat dirty, the suggest flow rates are also based on end of bulb life and a twenty percent reduction on output. This means the sterilizers rating much closer to real end users actual implementations which increase success rates. For the most part I would say there is no need to go larger than the suggested maximum aquarium size. The few instances where I might suggest that is if you know you are a lazy reefer with dirty yellow water and no matter what I say that’s the way it is going to be then I would probably get a unit which is rated for a tank fifty to a hundred percent of your tank size. That said a few dollar bag of high quality carbon is going to remove almost all of the yellowing compounds from the water so even if you are fairly lazy about water changes you can use some carbon and not have to oversize your sterilizer.

The other instance is related to installation. If your installation has the feed pump and the sterilizers output in the same area it is going to immediately reprocess or recirculate a lot of the same water which was just sterilized and significantly decrease the overall effectiveness. When the sterilizer says it is rated for a one hundred and sixty gallon tank with ninety eight gallons an hour of flow they are basing that off a how many times a day ninety nine point nine percent of the water is going to pass through the sterilizer a day with the expected sterilization effectiveness rate with each pass through. That means the best installation will minimize the re-sterilization of water which was just sterilized. For instance if you do put the feed pump and the sterilizers output in the same area of the sump you are going to continually recirculate and process water which was just sterilized a moment ago and reduce the volume of unsterilized water that passes through, reduce the effectiveness.

Two good installation options are to divert a small amount of water from your return pump through the sterilizer to one of your returns on the tank which will minimize unintentional reprocessing of the water through the sterilizer and function as intended. An install like this is probably best done when installing and plumbing the tank. Alternatively because the flow rate is pretty low it is normally safe to put the feed pump in an earlier stage of the sump like the skimmer area and have the output of the sterilizer feed into the return pump chamber. This will also maximize the unsterilized water passing though the sterilizer. Since sump designs vary you will want to make sure this will work safely with yours. One thing I normally don’t recommend is feeding the sterilizer from the overflow of your tank. There are ways to do this properly however controlling the flow rate is harder and there are often a lot of air bubbles that go down the overflow.

Couple answers to common questions. Will a UV sterilizer hurt the beneficial bacteria that filter my tank? A vast majority of the bacteria that filter your live on surfaces like sand , rock, media or even glass so this isn’t an issue however I probably wouldn’t have it on during the tanks initial cycle. Can I use a UV sterilizer with organic carbon dosing methods like vodka, bio pellets or Zeovit which rely on a different type of bacteria, some of which can be dosed? Most reefers would say it’s not recommended and I would probably agree. These methods are not completely understood and I would follow the manufactures recommendations or emulate other reefers who have had success with these methods and they most commonly don’t use sterilizers with reefing methods like this. Will a UV sterilizer hurt copepods, amphipod or other desirable microfauna populations? Most likely little to no impact. Most of these things are far too big to be impacted by the sterilizer, most of them live on surfaces rather than in the water column and the small amount of water passing through the unit means a UV sterilizer has very little impact on microfauna. Can I replace my quarantine tank or hospital tank with a UV sterilizer on my main tank? Nope, they are not replacements for good habits like this however they will likely reduce the chances you will ever need a hospital tank and a great idea if you know that you are never going to realistically quarantine fish before you add new ones to the tank. Will a UV sterilizer prevent all algae in the tank? It won’t have any impact on the algae growing on surfaces but I have seen it significantly reduce the spread of waterborne algae and photosynthetic bacteria like cyano. For instance you will likely find yourself cleaning the glass less frequently and while existing cyano patches won’t be impacted it is less likely you will find it in new areas.

Time to show you our install for the BRS 160. This tank is already plumbed so tearing it apart to send water from the return pump through one of the returns which is one of the better install options really wasn’t realistic. We also didn’t want to add additional pumps to the system which means we are going to feed the sterilizer with the plumbing manifold we set up earlier. We installed it on the end here furthest away from the return pump which is going to feed it. There will be some amount of re-sterilization with this install because some of the sterilized water is going to be sent back into the sterilizer by the return pump and some back to the tank. Our estimated was about a third or less of the water was going to get reprocessed. To compensate for that we selected a larger sterilizer. With a perfect install we could have gone with the smaller forty watt light version. Because we are reprocessing some of the water we needed to go larger. The forty watt standard would have been sufficient for this tank and the install solution but we ultimately went with the 50 watt high output. The reason we went so big on this was really more about dimensions of the sterilizer than anything. The shorter dimensions of the high output model just fit in the location we wanted to install it much better than the longer forty watt standard. For me neat, simple and attractive generally also translates to a safe quality install.

The manifold we installed in week five included a ball valve at the end we are going to use   to control the flow rate through the reactor. The flow rate is a critical step of the install so do not overlook the importance here. To fast and there wont be enough contact time to work properly, too slow and we wont have enough the the tanks water volume passing through the sterilizer to achieve the desired goals. Since this sterilizer is rated for for hundred and eighty gallons which is three times the size of the BRS160 we are installing it on we obviously have a significant margin of error here . The suggested maximum flow rate is two hundred and sixty gallons an hour and a number we absolutely don’t want to go above or there wont be sufficient contact time to sterilize the water. Because we have that room to play with this huge sterilizer we are going to shoot for two hundred and forty gallons an hour which will give us a buffer in both directions.

Again to adjust the flow rate we will use the ball valve. To measure the flow rate we will just collect some water at the output, time it and do the math. For instance if you collected a gallon in a minute it would be sixty gallons an hour. In this case because I have limited room I am going to use a graduated beaker to do the timed measurement and calculate the flow rate from that. You will notice we plumbed the intake to the bottom of the UV sterilizer and the output at the top. This is to make sure all the air escapes the sterilizer. If we had plumbed the intake to the top it would be easy for a lot of air to get permanently trapped in the sterilizer. How you plumb it will depend a lot on your space constrains but make sure to consider how the air will escape. The Plumbing is fairly simple. Just a couple 2” slip spigot to slip bushings to get the unions on the sterilizer down to three quarters of an inch, some blue pipe and a mix of spigot and standard ninety degree elbows. If you end up using a pump make sure it is something that can handle the head pressure from your install.

A Flow pump like a MJ1200 is rated for almost three hundred gallons an hour but it is not designed for head pressure like this and almost certainly not going to work in most UV installs. A DC pump like the Waveline or EcoTech Vectra is nice because you can adjust the flow rate with the control pad. The Waveline is also apex ready so you can do that with your aquarium controller. I have heard they might have a flow meter module coming out. Depending on how that works with an apex ready pump like the Waveline that could be a pretty cool combination for something like this. However most of us will elect for a much more affordable option with something like a quite one from Lifeguard which is probably the least expensive reliable option or a Sicce Syncra 1.5 pumpSicce Syncra silent which is one of the smallest options with the longest warranty. The Syncras have the ability to adjust the flow rate with the a knob on the front if you wish, however I have found limiting the intake like this can create additional noise with pumps and you are better off with a valve on the output. One last note on sterilizers. Some manufactures offer them with and without wipers to clean the quartz sleeve inside. Regardless of the brand most people will recommend not using the wiper version in saltwater because the steel rod can corrode overtime even with the best grades of steel. Here is a link to the UV sterilizer page on Amazon