As the pond begins to wake up after its winter sleep a few simple jobs done at this end of the year should help get things off to a flying start as the weather warms up. Equipment which has lain unused since the autumn needs to be prepared for the new season and the pond itself will probably benefit from a few final touches before things get underway in earnest.
Spring is also one of the most difficult times for fish, which have been dormant throughout the cold and now need to adjust to the quickening rhythm of life as the water warms up. However, bacteria and parasites will also be present in the water and will themselves be starting to become more active, which can pose a threat of disease, particularly to any fish which have been weakened by the strain of over-wintering. In addition to the routine seasonal maintenance, the fish-keeper also needs to keep a particularly vigilant look-out at this time of year for the first signs of illness.
Clarifiers, Filters and Pumps
With spring comes the return of the green water threat, so the pond’s ultra violet clarifier needs to be brought back into operation to counter the algae which cause it. As the UV bulb ages, its efficiency drops and less UV radiation is produced, so it needs to be replaced ideally each year. Spring is a good time to do this, since the clarification effect is most needed in the opening few months of the season, when the likelihood of algal blooms is at its highest. When changing the bulb, it is a good idea to check that the quartz tube it sits in is free of deposits or lime-scale – a dirty tube will also cut down the amount of UV hitting the algae.
Cleaning the bio-filter is another job for this time of year, paying particular attention to shifting any old sludge that has settled, so it does not get recycled back into the pond once you turn the pump back on. Be sure to use pond water or rainwater to wash the filter, rather than tap water, to avoid introducing chlorine and other unwanted chemicals into the system. If possible, it is often a good idea to try to time things so that you can run the filter for a week or two before the weather really starts to warm up and the fish become active, allowing the numbers of beneficial filter bacteria to build up.
If your autumn or winter maintenance did not include removing the pump, now is the time to lift it and clean it up – externally and internally – to ensure that the pre-filter unit is clear, the intake is not blocked and that the impellor is not fouled so that it can rotate freely.
If large numbers of leaves have found their way into the pond or a thick layer of sludge is sitting on the bottom, it is worth either hiring a pond-vac or using a wide-bore tube as a siphon, to suck up the deposits and dispose of them, to avoid storing up problems for later. Left alone, this material will begin to decompose as the warmth brings increased bacterial activity – leading to the possibility of excess nutrients to drive algal growth, not to mention depleting the dissolved oxygen in the water. Although ponds generally look very clear at this time of year, testing the water before everything really begins to get going will give you a better idea of what sort of condition it is in and also alert you to any potential problems before they become significant.
Finally, once the danger of frost is passed, delicate plants which were removed from the pond or bog garden for the winter can be returned and any plants which need dividing should now be split and replanted in suitable baskets, using a good, low-nutrient pond compost.
With all the season’s routine maintenance out of the way, you can safely settle back and wait for the temperature to slowly rise and hopefully begin to reap the rewards of you efforts as the new growing season gets underway.