I have a U.V. light so why is my pond still green?
Ok so you have done everything you have been taught and your pond is still green with algae. You have a good biological filter, you keep your pond pump running always and you have a U.V. unit and… green water.. What is wrong??
Most companies and even some pond supply retailers sell U.V. sterilizers as a catch all for all algae problems. But the truth is they only work for single cell or green water algae. Although both thrive in the same conditions the string algae is not being killed by the U.V. unit because it is not in direct contact with the U.V. like the green water algae is. And that is the secret to the magic of the Ultra Violet sterilizers work. As the water with the single cell algae spores pass through the tube in is damaged and kills it. Then when in dies it is more likely to clump together so the biological filter can filter it out. Without the U.V. the spores are too small to be filtered out.
It is important to note a U.V. light is not effective on their own.
Bio filters will provide a bed for good bacteria which helps to break down and starve out nitrites, nitrates that come from debris, fish waste and other toxins.
So why if you have a bio filter and a U.V. with all the bells and whistles do you still have green water? Could be one or a combination of many different issues.
Do you have the right sizes pump?
The first thing to check is if you have the right pond pump for the right U.V. It is very very important to follow the manufactures recommendations. If the water goes through the tube to fast it will not be in contact with the light long enough to do the job. So in this case more is not better. It is recommended that if your pump is to strong then split some of the water off to go part through the U.V. and part either to the filter or directly back to the pond.
It is fun to have a lot of fish swimming around in your pond. That is why you put the pond in in the first place right? It is ok to have a lot of Koi and other pond fish but it will require bigger filters, pumps and U.V. units. In most cases, much bigger than would be fitted to the amount on pond gallons. You may have 1000 gallons but if you have a full pond you may need to equip it as if it where 2000 or more gallons. And would require more partial water changes as well.
Does the bulb need to be changed?
Most U.V. manufactures state that the bulbs should be changed every 12 months. I feel that in about 6 months they are already starting to burn a bit weak and may need to be changed. It is easy (especially at night) to look to see if the light is still on. Be cautious to not tough the bulb with your fingers as the oil, sweat or dirt from your finger will heat up when the bulb is turned and it will break.
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