The Advantage Carbon Filter is designed to automatically remove any chlorine from city water before it enters your koi pond. Each filter contains over one cubic foot of activated carbon media. Additionally, these filters come with an automatic backwash system. Depending on the amount of water you are sending through the filter you can program it to automatically backwash from once to several times a week. This back washing assures the filter will stay clean and never begin to channel. Channeling is what occurs when a filter starts to plug up and the water begins to create a channel through the filter media. When this happens the water is exposed to only a fraction of the filtering media rather than flowing evenly through all the media thereby greatly reducing the filters efficiency.
How often do you need to replace the carbon media in the Advantage Carbon Filter?
There are a number of variables to consider as to how often the carbon needs to be replaced such as;
If you are only changing 200 gallons a week on average in your pond, you allow your auto fill to slowly replace the water and the chlorine level in your city water is .02%, one cubic foot of carbon would probably last 5 years without changing.
On the other hand, if you are changing 3,000 gallons a week on average in your pond, you are using a garden hose to quickly refill the pond and the chlorine level of your city water is .05%, one cubic foot of media would probably last 1 1/2 to 2 years.
If you want to be overly cautious you can just change out the carbon once a year. Because carbon filters loose their ability to filter out chlorine very slowly, another option is, after the first year, to start testing the fill water coming from the carbon filter once a month for chlorine. Then, at the first sign of any chlorine in the water, change out the carbon. This will now tell you, in the future, how long you can go before you need to change out the carbon in the filter again.