Perfect pond maintenance, serving a biological filter in spring

Have you been using your filter system all winter? Thats no problem as long as you are just circulating the surface water, nice and gently. But you may be finding that your filter is getting just as dirty now as it was in the high summer and you thought everything would slow down in winter. What? You havent looked? Better do so toute suite, because although it has been colder, it may not have been cold enough for the muck making of the pool inhabitants to cease altogether. However, it has been cold enough for the biological activity of the filter to slow right up. This means that although your filter is still operating mechanically, by straining the detritus out of the water, if the water is only 5C or less the bacteria in the filter medium are not digesting and breaking down the organic matter coming into the filter. But what is worse is that they are not coping with the ammonia coming from the natural metabolism of the koi and also the subsequent nitrite compounds resulting from the initial breakdown of the ammonia, both of which are so deadly to koi. So arm yourself with thermometer, ammonia, nitrite and pH test kit and get testing to give yourself a handle on what is really happening. The pH test kit is important because a high pH will multiply the poisonous effect of any nitrates and ammonia.

For those of you with just the hardy goldfish and their close relatives, you will find them easily coping with the winter merry-go-round of the pool environment, with or without filter. With koi, as much expense and effort spent on their behalf as you can afford has its returns. The onset of spring sooner or later is the most stressful time of year for these fish, so as it begins to get warmer, the filter must be in tip top condition so that the water quality in turn is as good as it can be.

Tool kit

You will definitely need: a bucket, a bucket with holes in the bottom, flat bottomed scoop like a cut down plastic milk container or square plant pot, screw driver.

Possibles that remove the element of Sods Law: PTFE tape, waterproof grease and if you are changing the lamp in the u/v clarifier, a new quartz sleeve if the u/v has one.