It's spring time and also time to take a hard look at your pond. Most of us have had to deal with an algae bloom in our pond at some time or another, how you handle the algae problem will be the key to your success in keeping your pond crystal clear!
Many people think that "cleaning" means a complete water changeout along with leaf and debris removal and mucking out the bottom of the pond as well. While it is important to clean out leaves and debris that have fallen into the pond and removing some of the muck at the bottom of the pond, it is important that we leave some of the "good bacteria" in the pond.
Early in the spring, your plants (iris, waterlilies and bog plants) are still asleep and have not begun the process of taking up nutrients from the pond. It is too early in the season for floating plants like water hyacinths and water lettuce as the water is still too cold. So, even though we think we are starting fresh with a "clean" pond. We have depleted the naturally occuring bacteria (the ponds immune system) and we are left with nutrients, water and sunlight. The perfect recipe for algae.
Note algae is not harmful to much of anything except our pride. Unless you are overfeeding or keeping the pond out of balance an algae bloom will be short lived.
We never recommend chemicals for a pond. Once you use chemicals you have to kill the algae, the dead nutrients remain in the water awaiting the dissipation of the chemical. You have really done nothing to help with the algae, just gotten into a chemical cycle ($$$). Remember the recipe for algae is water, sunlight and nutrients. Since you basically have those ingredients in you pond at all times, you must find a way to achieve a natural balance.
We do recommend that you add natural "good" bacteria to your pond, a biological filter is a harvest point for the bacteria. Also, when cleaning your filter, leave a trace amount of the good bacteria in the filter to help maintain a healthy balance. We call this, seeding the pond with "good" bacteria.
We also recommend oxygenators for your pond such as hornwort, vallisneria, anachris and other oxygenators to uptake the nutrients left behind from fish waste. Many oxygenators are hardy and can begin the uptake of nutrients early in the spring.
Marginal plants that grow above water like Louisiana Iris are also excellent for nutrient uptake and removal.
You don't have to rid your pond of algae before you start adding plants to your pond unless the algae problem is overwhelming. Once it warms up a bit, shade from water lettuce, water hyacinths and water lilies will help with the existing algae. Your shelf plants and marginals will now begin to be helpful in taking up some of the algae as well.
Try not to feed your koi or goldfish as there is plenty of nutrition for them in the water. We don't want their waste creating more nutrients to feed the algae bloom! You can add natural barley products or beneficial bacteria at this point and you should soon see progress and hopefully,the bottom of your pond through your clear water!