1. Add Quick-growing Plants
The main cause of too much string algae in your pond is an overabundance of the nutrients that string algae lives on. One way to reduce those excess nutrients, and thus the algae that lives on them, is to add plants that use the same nutrients to your pond. Two great ways to have your plants soak up tons of nutrients is to add plants that either reproduce quickly or grow larger. A little bit of a quick-reproducing floating plant like water lettuce in your waterfall box will reproduce like crazy, taking up a lot of those excess nutrients. Just grab some of that lettuce out of there from time to time and toss it, making room for more lettuce to grow in, taking up more nutrients. Alternately, marginal and bog plants like irises and cattails can take up lots of those nutrients with very little upkeep, and are especially good for dealing with the spring algae bloom that comes before your lilies are ready to pick up the excess nutrients.
2. Go Weeding
Simple and quick. Weeding string algae from your pond might be a bit wetter than weeding your veggie garden, but it should also go quicker. Just grab the biggest bits of string algae near the base, pull ’em, and toss ’em in a bucket. Done and done. Many pond owners underestimate the value of physically removing algae.
3. Get Your Koi to Weed For You
Koi love to nibble, especially when they’re not overfed. If you feed your koi a little less, you’ll be amazed at how voraciously they cut through a mess of string algae. Of course, decreasing how much you feed your koi will also limit your string algae in another way. Remember those excess nutrients that cause string algae to bloom in your pond? Well, a huge portion of excess nutrients in many ponds comes from overfeeding koi. Remember, if there’s any food left in the pond uneaten, you’ve fed your fish too much food.