How often your pond should be cleaned depends on many factors. The better your circulation and filtration, the less often your pond should need a “full” cleaning. Filtering the pond three or more times an hour, lots of aeration to keep debris from settling on the bottom, lack of dead zones, no gravel to trap debris, and oversized filters or bogs all help keep the pond clean as it goes along, lessening the need for annual cleanings. Your filters should be cleaned at least yearly, but a well-designed pond should easily be able to go three to five years or more without a “full” cleaning.
You can easily clean your pond yourself, however, if time or energy leads you to have a professional do it, here are some things to look for in choosing someone to do your pond cleaning.
- Where are they putting your fish while cleaning? If they use buckets or big trash cans to hold your fish, RED FLAG. They should be using a tub of at least 100 gallon size even for small fish, bigger and even several tanks for large or many fish. The tubs should be aerated while the fish are in them and netted to keep your fish from jumping out.
- How are they catching and moving your fish? A big ol’ net from the bait and tackle store is a RED FLAG. The fish should be caught in a shallow soft net designed for koi so as not to injure them. Any koi larger than about 14” should be then moved to the holding tank in a koi sock. This is a tunnel like net of solid fabric. The koi is first lifted to the surface in the koi net, then, still in the water moved into the koi sock. Both ends of the koi sock are picked up, moving the koi in water and in the dark to the holding tank, then the bottom end of the sock is released while the top is lifted, allowing the koi to slide out into the tank.
- Are they cleaning your filter and re-seeding it with fresh bacteria? If they tell you that you don’t need to re-seed a filter, RED FLAG.
- Are they cleaning your pond in June, July or August? RED FLAG. Even late May is debatable for cleaning ponds. By late May your fish are fully active and your plants are growing rapidly. Cleaning a pond then puts way too much stress on your fish, damages your plants at the height of the spring growing time and sets your filter back as if it was new. It takes a newly cleaned filter almost a month to cycle, during which time your now very active fish are producing lots of waste, ammonia and nitrite, building up toxins in the water that the filter can’t fully handle until it finishes cycling.
A typical pond cleaning should consist of, pumping half or more of the water out of the pond and then catching the fish to put in their holding tubs. Pump the rest of the water out. Use a high pressure hose nozzle or a pressure washer to wash down the side and get any loose debris to the bottom. Vacuum the debris / muck out of the bottom. Do not try to get the rocks or the liner completely bare, some “slime” on them is beneficial. Completely clean your filter/s at this time. Waterfall filters should be completely emptied and all parts cleaned. Bog filters should be vacuumed out through the standpipes and water even run in from the top to force muck out of the gravel and back into the pipes to be sucked out. Pressurized filters are all different, follow the owner’s manual for them. This is the time to change the bulb in your UltraViolet light, as they are only really effective for about twelve months. Refill your pond, putting plenty of dechlorinator in and be sure to reseed your filter with fresh bacteria / enzymes.
Pond cleaning is usually done in the spring when it is needed, but may just as well be done in the fall. It should NOT be done in the summer. For our area, we do not recommend cleaning be done after the first week in May or before the last week of September, as during that period doing a cleaning puts too much stress on both your fish and your plants, and cleaning your filter when the fish are fully active puts too much load on it as it tries to re-establish itself.