uv light

I Have A UV Light In My Pond But Still Have Green Water

John writes, “I have a 1500 gallon backyard pond and have installed a uv light in it which was supposed to help with green water problems. It doesn’t seem to be helping very much, and I wondered if I did something wrong?”

Answer: Hi John and thanks for the question. Your plan to use a uv sterilizer in your pond to combat green water is a good idea. In truth, when you hear companies talk about fighting pond algae problems with a uv filter, it’s single cell, or green water algae that they are talking about specifically.

In contrast, string algae won’t be affected because it can’t pass through the tube and be exposed to the ultra violet light, which does all of the damage. In the case of green water, this discoloration can vary in a pond and the degree of just how green and dense it will get is totally dependent on how many little, single cell algae you have growing in the pond. These can expand in number quickly when conditions are right so a pond can be pretty clear or lightly tinted one day and totally green the next.

A pond uv light basically irradiates these little critters and will either damage or kill them and in doing so, it makes them clump together in a larger mass which is more easily filtered out of the water by a good quality pond filter. What’s interesting is that individually, these single cell algae can be so small that they’ll pass right through many filter systems.

Which brings me to an important point. A UV system is not the only required component in a small pond’s filtration system. Ideally they should be paired with a good biofilter which actually captures and breaks down these dead or damaged algae cells. UV will do nothing to reduce nitrites, nitrates, or other material which can be broadly classified as nutrients coming from fish waste, among other things. Only a biofilter will help with these so it’s important to include this in the mix.

Green Water Continues

Interestingly, many people who have UV light installed in their ponds may still have problems with green water. This usually indicates that something will need to be adjusted to get this to work better. Most manufacturers have ratings for how much water flow should run through the uv over a period of time. For example, a very common rate would be the full gallon volume of the pond should circulate through the uv and filter system once every hour. This insures that the water and algae cells are passing in front of the uv light frequently enough to be affected.

It’s best to follow the product maker’s suggestions but if you need to, it may also be useful to slow the water flow rate down a little bit if you’re still having problems. A slower pass rate may help expose the algae to the light a bit longer and this can make a difference in performance. Normally some type of restriction valve can be put inline and help with this flow rate control.

You may find that some uv lights come with several suggest flow settings. A higher or faster rate would allow the unit to work as a clarifier, which means it may control algae, but not decimate things like beneficial bacteria so much. UV is indiscriminate in what it will kill or control…good bugs, bad microbes, viruses, and algae are all targeted.

On the other side of the flow rate coin, a slower flow rate will provide a sterilizer effect on the water. A more thorough eradication of all affected elements will be made because of the longer exposure time to the ultra violet light. Either rate, or somewhere in between will likely create the best results for your pond in terms of algae control. In an ideal setting, you would want more a clarifier effect but this may not be possible for every pond.

Another reason why uv light may not be getting the job done is that the uv bulb will need to be replaced from time to time. Many people assume that because it’s still lighting up that it’s working fine but this isn’t always the case. Most bulbs have a operational life where they will provide ample ultra violet radiation and then begin to drop off in terms of performance. Twelve to fourteen months of operational life is common. After that you’ll likely want to replace them for improved performance.

And finally, if you’re in the market for a uv light or considering it for your pond, it’s important to make sure you get one that’s rated for your pond’s gallon size. A pond owner really shouldn’t scrimp on any of the important mechanical components in a pond, such as the pump or filter system. UV light is no different. Remember that to work well, the full gallon volume of the pond should probably pass through the uv pond filter at least once per hour, all day long.

With a bit of troubleshooting and detective work, you can get better performance out of your pond uv light and in doing so, you should be able to control green water algae without the use of chemical algaecides.

Choosing A Pond Skimmer

by Mark

Bob sent in this pond question recently. “I have been doing some research on pond skimmers. I see some of these products say they are good for 1000 gallons. I don’t understand what the gallons of a pond have to do with surface skimming. I would think size of the pond surface should be the consideration when trying to find the right size of skimmer. Am I missing something?”

Answer: Bob, thanks for the great question.

A pond skimmer, for those that may not know, are devices that are installed in smaller ponds, usually on the opposite side of a water fall that capture and trap unwanted material that enters the pond. They can help keep leaves, paper, or just about anything else from settling into the pond. Inside the skimmer is a chamber or basin wither a capture and filtering screen. It can be looked at as something of a prefilter which can help protect a true pond filter from getting a lot of gunk in it.

Pond skimmers are one of those things that not every single small pond owner will need, but they sure can be a time saver when it comes to keeping a pond clean. A skimmer won’t necessarily capture every bit of material that falls into the pond. Particularly heavy or poor floating stuff may sink too fast to end up in the device, but for lighter, floating debris, a skimmer can be a great tool to have.

So now on to Bob’s question.

In a nutshell, it makes sense in terms of your point about the surface size being the key issue but let me suggest why other factors are also important to consider. There are several things I would think about when choosing a skimmer to fit my needs.

First, regardless of the size of the pond (and I say this within reason) if your pond get’s a lot of debris a bit bigger skimmer will handle this load better and you may not have to clean it out as frequently. The maintenance routine, to me, is important because some folks don’t like to work on their pond every day and some may only have time on the weekends as an example.

Also keep in mind that a pond skimmer, while optional, is a very real part of the overall pond filtration system. These should always be best suited to the overall pond size if possible and I would also add that in terms of choosing something like a pond filter set up, fish loading will come into play here too.

Ideally the full pond volume of water should pass through the entire system at a recommended rate for effective filtration. Normally in ponds with fish you want the full gallon volume to circulate once per hour or so. So all of the components in this system must be able to handle this degree of volume…whether it’s the pump, biofilter, uv light, or skimmer.

Some skimmers, although not all, may actually hold the pump, and have some additional filtration capability other than a simple mesh screen to catch some of the larger bits of debris. A finer, or tighter screen will capture smaller bits of material and do more of the grunt work for you. However in doing so, it will also probably require more routine cleaning.

Like all the other components in a pond you primarily need to think about what your needs, wants, and demands will be on the skimmer and choose, as best you can according to that.

Fortunately most pond retailers have a good understanding of what will work best in most situations, so use their knowledge of the components should you need to in order to get the best fit for your pond.

Can A UV Pond Filter Control Algae?

by Mark

A UV pond filter may be one of your very best options at controlling algae in your small pond or water garden. UV or ultraviolet light is touted by manufacturers as a very good tool for algae control but some of the claims need to be clarified to ensure that this type of device will actually help you with your current problem.
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A Fish Pond For Koi – The Basics

by Mark

A fish pond in the backyard is something that many people dream of owning. Yet for all of the relaxing benefits of a small pond, they can also be a source of many headaches if they’re not built or set up right with the proper equipment. In the article that follow’s we’ll cover some of the basic materials that will be useful in any type of fish pond.

If you are looking to construct a fish pond for koi, it is important to follow some basic steps to ensure the success of the pond and the heartiness of your precious koi. Where to construct the pond and what shape to design it in are two fundamental elements that should be decided upon first. It is best to locate the pond where you can access it easily while keeping it protected from the natural predators that will look for your fish. The shape of the pond also is important, not only to increase the pond’s aesthetic value but also to increase the chances of bringing your fish to their full potential.

There are a few supplies than one cannot do without when introducing a koi pond into the landscape of their backyard. These include pumps and filters as well as drains and skimmers. There are also lighting considerations for illumination and controlling algae. The easiest of these to attain is the skimmer, which serves the same purpose as the large scoops that you would use to clean the surface of a swimming pool. The skimmer will be used to collect leaves and other debris that may fall into the pond in order that the pond be kept clean and so that the fish remain healthy and free of disease.

A number of different filtration systems can be implemented in order to ensure a thriving pond. The primary one is the biological filter, which serves the purpose of converting the nitrogenous waste of the fish. This is known as the nitrogen cycle. It is of the utmost importance that the biological filter be kept immaculately clean so take extra care in choosing one. Be certain it is easy to service and that you will be capable of doing so. An unclean biological filter is the undoing of many a backyard fish pond. Bio-filters come in two distinct types, the aerated and the non-aerated. Examples of aerated filters include the Moving bed type as well as the trickle or bakki shower filter. Examples of the non-aerated kind include the Cross flow and the Sand filter.

Many types of algae can be kept in check with a good working biofilter but there are others where a different type of technology may be needed. In order to control and discourage the growth of planktonic algae you may need a source of ultra-violet or UV light. The UV light is used to prevent a condition that can afflict an unhealthy pond known as green water. This occurs when the filtration system is incapable of filtering out all of the naturally occurring nutrients that the algae feed upon and even the single cell algae itself.

A second type of filter that you may need is called the mechanical filter. The primary purpose of this system is to get rid of solid waste that could clog the Bio-filter. This filter must be kept very clean, so it should be place in an area where it can be cleaned and checked often. Sometimes referred to as a settlement chamber, this system can often be accomplished using gravel, sand or a sieve screen. Also many of the new biofilter designs have a sort of pre-filtering mechanical component in them as well.

Finally, you will have to choose a form of liner to protect the base of the pond and to line the walls. Leave room in the liner to cut out a bottom drain, so you will be able to give the entire unit a thorough cleaning.

As you can see, there are several key considerations on equipment and pond supplies that will be useful for fish pond construction and management. And while it may seem to be complicated, the layout of a fish pond is fairly simple and particularly when you understand the basics of what each piece of equipment will do and why it’s important.