GARDEN POND SPRING THAW
by Erik Tate, Operations Manager of Water Garden News
This time of year can be a time of extremes. For many of us it can be below freezing one week and in the 70's the next. Yet, we know that warm weather is fast approaching and our ponds will soon be waking up from their winter dormancy. As always, water temperature (not the calendar) is your guide to pond maintenance.
One of the first things that you will notice as the water temperatures increase is that your fish are slowly becoming more active. Your first inclination may be to feed them. I recommend waiting until your weather is somewhat stable and you are not expecting prolonged periods of below freezing temperatures. Wait until the water temperatures are stable at 50 degrees or above before beginning low protein fish food for koi. Goldfish can be fed at slightly cooler temperatures.
Another early change that you will see in your pond is algae growth. Your pond water may be turning green or you are noticing bits of string algae in clear water. Even in an otherwise well balanced pond algae growth in the late winter and early spring is normal. Algae will start to grow with the increase in temperatures and available sunlight. Normally with the correct number and types of plants and with a properly sized biological filter operating, algae growth can be kept under control. We can't expect our biological filter and plants to be much help in combating the algae at this time of year because algae will grow at much cooler temperatures than the filter and plants will function in. Many of the algae types that we see in our pond will grow well in water temperatures in the 40 degree range whereas the bacteria that work in our filters need temperatures above 50 to begin their life processes.
What can we do you may ask to limit the algae growth while we wait for warmer temperatures? If we remove the nutrients and the light then the algae will die. We can't expect to totally remove the nutrients and light but we can reduce it dramatically. To begin with, remove any dead or decaying organic matter from the pond. Use a pond net to remove leaves and other debris from the pond. An algae net is fine and can be scooped through the water to remove filamentous type algae. You can also use a pond vacuum to remove excess debris.
Remember to also check any external filters and to make sure the bottom is free of sludge build-up. Ensure that rain runoff cannot flow into your pond. This can carry a lot of nutrients from your lawn into the pond and cause increased algae growth. Buy products that help break down the organic waste and reduce the nutrients feeding the algae in the pond.
We can also reduce algae by limiting the amount of sunlight reaching the pond. Since the plants are not growing we don't have many options here. One option though is to add a pond dye to the water until our plants are growing again. Pond dye not only reduces the sunlight but can also make the pond more attractive.
Now is the time to obtain some of the tools and supplies that will be needed when we once again have an active pond. A large tub around 20 to 100 gallons is very useful for housing fish while cleaning, remodeling, or making repairs to a pond. Larger ones also make good quarantine or hospital tanks.
You will want to monitor water chemistry early in the season, at least until the pond is stabilized for the season. You should have water test kits for pH, ammonia, and nitrites at a minimum. Ammonia and nitrites can spike very quickly during the spring when our filters may not be working at maximum capacity. A pond thermometer will let you know when to begin feeding your fish a low protein food.
If you need to replace your filter media do it now before time for the bacteria to establish in your filter. Biological clarifiers should be added after the pond water is in the upper 50's.
Always have a dechlorinator on hand. You never know when you may have to add a lot of water or do a water change. This can save your fish. You still have a little time, but after the water has warmed into the 50's you will need fish food and fertilizer for your plants.