As water temperatures increase with the heat of the summer sun, they will also raise the metabolism of your fish and the amount of faecal matter they produce. Combines together with seasonally high levels of algal growth this can create a dramatic peak in the waste that reaches your pond filters. However without proper maintenance these filters can fail causing disastrous problems for your fish.
Biological filters containing non-biodegradable sponges are perhaps the most popular forms of pond filters on the market. They work by creating a highly oxygenated environment ideal for attracting microscopic aerobic bacteria. These friendly bacteria are able to break down fish waste - as well as other debris that enters the pond - into what eventually become harmless by-products. It's extremely important to realise that these bacteria are the powerhouse of your filter and are essentially living in a highly specialised environment. However if this specialised environment isn’t maintained correctly- it can easily be destroyed.
Problems can occur if the pump fails or is switched off as this will cut off the bacteria’s life-giving supply of highly oxygenate water killing them by asphyxiation. Besides this the biggest threat to your bacteria occurs when the sponges are washed out in tap water. The damage is made in two ways. The first is down to the temperature differential of tap water compared to the pond water. This can be as much as 15 degrees Celsius during the summer causing a temperature shock which can kill off a significant proportion of your valuable bacteria.
The second and an arguably more destructive problem is to wash filter sponges in tap water, the problem here is down to the reactive chemicals added to it. These can include chlorine, chloromide and trihalomethanes, and are used to prevent our drinking water for being contaminated by harmful bacteria. Unfortunately these chemicles are unable to differentiate those from the friendly bacteria found in your pond filter.
The best way to clean your filters safely is to rinse it in water that has been taken from your pond. Then, when rinsing the waste out of the sponge, try not to remove the entire residue as this will act as nourishment for the next generation of aerobic bacteria. If you are unsure as to when you should clean, it will differ depending on which type of filter you are using. Pressurised filter systems will have an indicator which shows when a high level of waste begins to over pressurise the system. If you have gravity fed system, the cleaning process should be undertaken just before the filter sponges become blocked. If left, this would cause a redirection in the water flow.
Warning: Never turn off your pond pump as without the constant supply of oxygenated water to the filter, waste will break down anaerobically within the pond adding even more toxic by products to your water.
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