Algae….Should We Hate It?

Believe it or not, there are benefits to algae.

• 1. All algae provides food for microorganisms which larger animals and fish can eat.
• 2. Surface and hair algae provide food for fish directly.
• 3. All algae absorb excess pond nutrients like ammonia, nitrate, and phosphate.
• 4. Suspended algae provide some shade to pond animals and plants.
• 5. All algae provide oxygen during the day (CAREFUL, they use it at night).
• 6. Hair algae provides a soft spawning site for fish.

• Limited amounts of algae are a good thing. Algae is a necessary part of a healthy, balanced pond. But you can have too much of a good thing. Then it becomes a bad thing.

The disadvantages of algae

• 1. Suspended algae reduces clarity so that animals and plants cannot be seen in the pond.
• 2. All algae reduces oxygen levels at night.
• 3. All algae may cause pH fluctuations.
• 4. All algae may block light from reaching plants hence may cause the death of aquatic plants.
• 5. Hair algae may cause the death of aquatic plants through strangulation.
• 6. Hair algae can clog pumps, filters, etc.
• 7. Finally, many people find algae just plain ugly!

• Types of Algae

Hair or string algae is a slimy, bright green, filamentous algae that grows up to a few feet in length. It clings to the side of the pond, pots, and any other surfaces. It can smother plants and clog filters. On the up side, it removes nutrients from the water and thus reduces the concentration of suspended algae so you can see through the water better. Hair algae seems to like moving water and it is not affected by a UV sterilizers because it does not pass through them.

Green surface algae is the best kind of algae to have. It is found on the surface and is very short. It is a vital food source for snails, tadpoles, fish, fry aquatic insects and other aquatic creatures. Brush algae is a less advantageous type of surface algae with longer filaments that suffocate plants.

What to do……

The following 14 tips may help to reduce the algae in your pond.

• 1. Reduce the quantity of fish in the pond and/or the quantity of food given to the fish. Fish waste and fish food both yield algae food.
• 2. Increase the quantity of plants in the pond. Plants are nutrient sinks that compete with algae for light and nutrients. This could include additional water lilies; a veggie filter (about 10% of the surface area of the pond with 50% of the pond volume pumped through per hour); floaters such as water hyacinth, water lettuce, duckweed, etc. in the waterfall, filter or pond surface; submerged plants such as anacharis, cabomba, etc.; and marginal plants such as iris, cattails and sweet flag.
• 3. Decrease the quantity of light into the pond. This could include using a tarp part of the day, floating plants, lilies or even moving the pond (pretty drastic move).
• 4. Use a commercial bacterial and/or enzyme concoction such as Microbe-Lift or BZT Aquaculture or others.
• 5. Add tadpoles and/or snails to consume debris and algae itself.
• 6. Remove debris, dead plants and animals, dirt, etc. from the bottom of the pond.
• 7. Increase the size and/or efficiency of the filtration system. Clean out the filters on a regular schedule.
• 8. Add a UV sterilizer for suspended algae.
• 9. Physically remove hair or string algae.
• 10. Be sure no chemicals run off the surrounding lawns into the pond. Fertilizers directly feed algae. Pesticides will kill the good insects and microorganisms in the pond, which feed on algae. Herbicides will kill aquatic plants and maybe some algae but once the higher plants are injured or dead, the algae will come back with a vengeance To be on the safe side, use NO CHEMICALS NEAR THE POND!
• 11. In ponds that are low in potassium, add potash (potassium only fertilizer). This will help higher plants to grow if they are limited by the lack of potassium (K). If the high plants grow they compete better with the algae. Always test the water for need before adding any chemicals.
• 12. Check the pond's pH. If it is overly high (above 8), finding a way to lower it may help reduce algae. All pond owners should have water test kits covering a few important tests and one of these is pH. If you don't have one, contact our Koi Health Advisors, Greg or Marlene who do have these tests. If you are on a public water system in Western NY, unless something has happened in your pond to affect the pH, you should not have a pH problem. If your water supply (well water perhaps) is at a higher or lower pH, in the long term it is better to deal with the water chemistry that you are given than to try to adjust it all of the time. A short term solution is adding a pH-Down solution. BE SURE TO TEST FIRST!
• 13. Add bentonite clay to large or koi ponds. The clay acts as a coagulant and settles out algae. It will cloud the water in the short term but will shortly thereafter clear up. It also benefits the koi by providing minerals.
• 14. The use of barley straw (other straws do not work as well) in a net bag, pantyhose or other open container placed in the center of the pond, or at an area of high surface agitation such as where the waterfall spills. The bag is anchored near the water's surface (may require a float), where oxygen content is higher, more sunlight is available, and the algae hang out. One application lasts about six months, or in our case, the entire season. Barley straw has not been shown to have any negative effect on aquatic plants or animals. In fact, insects and microorganisms live in the straw and provide food for higher animals, and aquatic plants grow better without having to compete with algae for sunlight. This works best on suspended algae and not on string algae.

• The dosage should be about 1 pound of barley straw per 225-250 square feet of water surface, adding more or less depending on the starting clarity of the water. It takes 6-8 weeks, depending on the temperature, before barley straw will begin to inhibit new algae growth. Because it does not kill existing algae, it may take a while for change to be noticed. Algae cells have a finite life span and are dying all the time. Check on the straw occasionally. If it smells or rots away, it should be replaced. The best times to put out the straw are in early spring before algae gets started and again in early fall. When you add a new batch, leave the old batch in place for a month till the new batch gets started.

Factors that affect the straws potency:

• 1. Oxygen levels must be high enough to create the inhibitors. If the water's oxygen content is too low, the straw may take too much oxygen from the water, creating a serious problem for the fish.
• 2. The inhibitors are deactivated by dirt, sludge, etc. Thus in ponds with more of these substances, more straw is needed for the same effect.
• 3. Temperature is a major factor. In cold water, the straw may take 3 months or more to be effective. In warm water (70 degrees F or more), it may only take 1 month. Likewise, the straw will last longer in cooler water.

• Unless you wish to have a sterile environment that never stops fluctuating, do not use chemical algaecides or herbicides. Even in sterile fountains, wild birds could be sickened or killed by drinking from the water.

.

Direct comments about this Web Site to webmaster.