Seasonal Pond Care

With countless products available for use in our water gardens, it can become a little overwhelming. Should we be adding a dozen chemicals to our ponds every week? What should we be doing? Well, to a great degree that is very specific to each individual pond. There is no right answer that will apply to every koi pond and water garden. However, there are some basics that almost every pondkeeper should be doing to take care of their pond. Each pond may have its particular additional needs such as algae control.


In Spring, the water begins to warm and we can see the pond beginning to come back to life. This is an important time to get the pond going in the right direction for a rewarding season.

  • Un-winterize the pond. Anything that you had done to prepare for winter can be undone once freezing weather has passed. If you turned your pump off, it can go back on, etc.
  • Start feeding your fish again when the water temperature reaches a constant 50 degrees. Feed a cold-weather food until the water temperature reaches 60 degrees at which point you can move to your full-season feeding program.

    If there has been an accumulation of leaves and other debris over the winter you should remove this now. Leaves can be removed with a skimmer type net. Products like Microbe Lift Sludge Away will help accelerate the natural decomposition of this debris.

    You can also use a pond vacuum to remove the leaves and sludge from the bottom of the pond. You could also try to use a shop vac but this removes a lot of water in the process and may not be the best choice. If there are lots of leaves and sludge accumulated in the pond to the point that you can not remove this easily a complete pond cleaning may be necessary. A complete cleaning will upset the balance of the pond and actually interfere with algae control but should you decide to go this route you can use the following method.
    Pump water from the pond into a large tub or other container. The exact size will depend on the number and size of fish that you have but should be as large as possible. It may be necessary to cover the container with leaf netting or something similar to keep the fish from jumping out especially if you have koi. This container should be in the shade if it is hot out. Continue pumping the water out of the pond until it just covers the fish. Use a fish net to catch the fish and place them in the container with the water just pumped from the pond. Also the plants can be removed if repotting is necessary or left in the pond. If removed they should be kept in the shade and covered with damp newspaper. Underwater plants should be kept in a container of water. After you pump as much water out of the pond with your pump as you can, you will want to use a shop vac to finish up or you can use a large dust pan and broom with a bucket to finish removing the sludge. Do not try to scrub the velvet type algae that may coat the liner as this is beneficial. Do not use any chemicals. After the pond is clean you can pump the water with the fish into the pond and then put the fish back into the pond. Add a dechlorinator to remove the chlorine and slowly add water from the hose to finish filling the pond. The plants can be placed back into the pond during the filling process.
  • Fertilize each plant and place at appropriate depth. Lilies and Lotus should be fertilized every 3-4 weeks, marginals every 5-7 weeks.
  • Add new plants as needed as the weather becomes appropriate for each plant. Add floaters such as water hyacinth and water lettuce (late spring after danger of frost has passed).
  • Turn on Ultraviolet sterilizer after the biological filter is working properly and the water starts to turn slightly green.
  • Divide and repot plants as needed.
  • Begin cleaning your filter as needed. Ponds with a skimmer or other pre-filter will need that skimmer/pre-filter cleaned most frequently. On average this is once a week, but some may need to clean more, others may be able to go a month between cleanings. If this filter is primarily mechanical (physically traps debris) and you also have a biological filter, then it is OK to hose off the pre-filter media. Your biological filter needs to only be cleaned when the flow of water is being restricted due to accumulation of debris. When cleaning a biological filter, do NOT over-clean. It is only necessary to remove the debris that is restricting flow. Over-cleaning the filter can destroy the bacteria that has colonized on the media. If possible, avoid chlorinated water.
  • A few things you may need: Fish net, Dechlorinator, Microbe-Lift PL, aquatic plant containers, Aquatic Plant Soil, gravel, a vacuum, fish food, and a thermometer.


    • Remember to continue fertilizing your plants as detailed under “Spring”
    • Remove dead foliage from the pond. The leaves of plants will yellow and brown as they age. When this happens, it is best to cut them off. This reduces debris buildup in the pond, provides more room for new growth, and improves the appearance of the pond.
    • Feed your fish well. Do not over-feed. Feed no more than the fish will eat in 5 minutes. Feed 1-3 times per day.
    • Continue cleaning filter as needed, making sure not to over-clean.
    • Maximize your aeration. Warm water holds less oxygen, yet the fish use more oxygen in warm water. Make sure you have plenty of aeration running 24/7. Aeration can be supplemented by using an air pump or additional pump.
    • Continue use of bacterial products like Microbe Lift PL.
    • Enjoy! This is the time to sit back and enjoy the work you have put into your water garden.


  • One of the most significant events of Fall is, of course, when leaves begin to fall from the trees above. If these leaves get in the pond and decay it will throw off the ecological balance of a water garden. One option is to use a net to skim leaves off the surface of the pond as they fall, but this can be a daily chore. Also, don't expect a skimmer type filter to get the leaves. Skimmers are designed to get the occasional leaf or other floating debris.

    Heavy leaf fall can clog a skimmer several times a day. Installing leaf netting over the pond will be easier to maintain.

    It is best to try to minimize the amount of accumulated sludge, decaying plant debris, etc. from the water. This can be done with a net, by siphon, or by use of a Pond Vacuum. Using Microbe Lift Autumn Winter Prep will also help accelerate the breakdown of organic debris in the pond.


    • Feed fish appropriately. The water temperature is dropping now and we should be feeding our fish less as their metabolism slows down. Hopefully you have been feeding your fish well with a high protein food this summer to allow them to build up a reserve of fat to help them through the winter. After the water temperature drops to the sixties you should decrease the amount of food given and feed only once a day. A wheat germ based food is good at this time as it is easily digested. Microbe Lift Cold Weather formula is an excellent food at this time of year. As the water temperatures continue to drop to below 60 degrees you should feed only two or three times a week. It can take your fish two or three days to digest food at this temperature. Once the temperature drops below 50 degrees you should stop feeding altogether until spring when the water temperature remains above 50 degrees.
    • As organics decompose in the pond they can produce toxic gases that could be trapped in the pond if it is covered by ice for more than a few days. It is important to keep at least a small area free of ice so that these gases can escape. Do not break the ice as the shock waves created can damage or kill your fish. One of the easiest ways to do this is with a floating pond de-icer. This device floats in the pond and has a built in thermostat to turn the heating element on when the water temperature drops below 40 degrees. They can also be used to keep a small pond from freezing solid allowing you to keep your fish alive.
    Protect your fish. With their slower metabolism and the absence of plants our fish are more susceptible to predation by raccoons, birds and other animals. If you took our advice and added leaf netting to keep the leaves out of your pond this should protect your fish as well. A Koi Kastle will help your fish be more comfortable by providing a place for them to hide. One of the most effective methods of keeping predators away from the pond at any time of the year is a motion activated sprinkler. This device senses movement with a motion detector and sprays any intruder with a burst of water frightening them off.


    • Prepare the plants. You should have stopped feeding your plants by now. As the foliage on your hardy plants begins to die back you should remove any dead and dying leaves and place the plant deep enough in the pond to keep the roots from freezing. While it is true that some marginal or shallow water plants will survive even if their roots freeze solid it is best to lower all of your plants below the ice zone.
    • Prepare the pond. If your pond is too small or shallow to offer protection from freezing temperatures then you still have other options. You can add a floating deicer, which will keep an area of the pond above freezing. If your pond is not too large and does not contain any fish you can place a cover such as plywood over the pond and cover this with bags of leaves or bales of straw to provide insulation. A tarp should also be placed over the straw to keep it dry to provide better insulation. A basement can provide protection if you remove the plants and store them either in their original containers or in peat moss. A method that I like is to build a temporary shelter over the pond. Lumber or PVC pipe can be used to construct a framework over the pond. Place clear plastic over this and weight the plastic down with soil or stone. This frame should hold the plastic a few feet above the water. Greenhouse type plastic is best but construction grade plastic should last the winter. This method works very well and is basically like moving the pond to one USDA hardiness zone higher. On clear days the sun warms the water and even if covered with snow there is good insulation over the pond. Some tropicals can be wintered over this way in mild winters even if you live in zone 6 or 7.
    • Plants with special needs. Some plants do not like being submerged in the pond through the winter. Iris ensata formerly know as Iris kaempferi a Japanese Iris should be removed from the pond and planted in the yard until spring when new growth starts and it can be placed back in the pond for the summer. Lobelia cardinalis ( Cardinal Flower) should be removed from the pond and planted in the yard for the winter. This plant should have a few inches of mulch over it as well. You will have more success wintering over Cannas if you remove the rhizomes from the pot and store in slightly damp peat in a basement or other cool area.
    • Tropical plants. Some tropical water lilies will bloom all winter if kept in a tub container inside and given at least six hours of bright light. You can also winter them over by removing the tuber from the pot after the foliage has died back from a freeze. Place the tuber in a container of slightly damp sand or peat moss at 50 degrees. In the spring you will need to heat the tuber in an aquarium to about 75 degrees to trigger its growth before moving outside. One choice with tropical plants is simply to dispose of them after freezing weather and replace them in the spring. This way you get to try new plants and colors next season. If you want to try wintering over your tropical plants there are a few methods worth trying. Many tropical plants can be brought inside and treated as a houseplant for the winter. Umbrella Palm, will do very well with medium light levels. If these are in no-hole containers then no special care is needed otherwise keeping the pots in a tray full of water is needed to keep the plants wet. Water hyacinths and water lettuce require more care than they are worth; it is much easier and less expensive to replace them each spring. If you still want to make the effort they require 10 hours of intense light and temperatures above 70 degrees.

      Pumps and Filters

        Prepare the equipment. Depending on your climate and other factors you may or may not want to run your pump and filter system through the winter. If you live in a climate with temperatures mostly well above freezing then it will be to your advantage to keep your pump and filter running through the winter. The bacteria in your biological filter will not be active at low temperatures but it will remain alive as long as you keep it supplied with oxygen-laden water. When spring arrives and the water temperature is rising the bacteria can start to work immediately keeping the water quality good for your fish and helping to control the algae. Should you choose to run your filter through the winter it is a good idea to minimize the water circulation in order to take advantage of the layering effect of the water. (Water temperature is densest at 39 degrees and the water on the bottom of the pond will remain at this temperature even with freezing temperatures on the surface.) Some ways to minimize circulation is to turn off bottom drains if possible, place intakes to pumps/filters at mid-water, turn off surface skimmers, (you do not want to circulate top or bottom water in the winter), place your intakes closer to the outlets in the pond (waterfall or fountain), and or turn the pump down. These actions will allow the biological filters to stay alive without interfering with the layering of the water. Massive circulation of water in the winter can super chill the water by exposing warmer pond water to below freezing temperatures leading to the death of the fish. One problem with running a pump and filter in the winter is the potential of major damage to your filter and plumbing system if the power goes off for extended periods and you are not at home to make sure that no water is present in the filter and plumbing. If water is allowed to freeze in plumbing, UV's and filters this can lead to breakage requiring replacement of these units. If your system is designed to allow the water to flow back into the pond in the event of a power outage then these problems can be averted. If you have a check valve installed in your system you can use a long piece of small tubing or wire to hold the valve open to allow the water to drain out.

      You can turn off the pumps and filters for the winter. Cold water holds much more oxygen than warm water and the fish's respiration is slow therefore you should not need the circulation and aeration. The bacteria in your biological filter does not work in cold temperatures so the only reason to run the filter is to keep the bacteria alive. If you turn off the pump and filter for the winter be sure to drain all plumbing. External filters, UV's, and external pumps will need to be drained. Submersible pumps should be left in the pond or in a bucket of water in a warm place to keep the seals from drying out. If you choose this method be sure to clean the filter before starting up in the spring.

      A check list for Autumn/Winter pond care

      • Before the leaves begin to fall, cover your pond with one of several sizes of leaf netting (It is much easier to keep the leaves out than to remove them after they fall into the pond)
      • Fall is a good time to divide some types of aquatic plants (waterlilies and iris)
      • Remove dying plant foliage from the pond as it will decay and pollute the water.
      • After your hardy plants have stopped growing, cut back the foliage and lower the pot to the bottom of the pond.
      • Stop feeding your fish after the water temperature has dropped to the upper forties.
      • Also when the water temperature has dropped into the forties, reduce the circulation of the pond water by either turning off the pump for the winter and draining of all the plumbing or preferably by placing the pump or the intake to the pump closer to the water outlet (waterfall etc.) and pick up water from mid-level of the pond. Also turn down the water flow. Keeping the water flowing through your biological filter allows the bacteria to live therefore giving good water quality early in the spring.
      • If you keep your filter running through the winter, you must take precautions against the freezing of water in your plumbing should there be a power outage .
      • You can add a floating de-icer to keep an area free of ice. This opening is necessary during periods of ice cover to allow an exchange of gases.


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