Pond and Lake maintenance using Diatom Algae

Pond and Lake maintenance using Diatom Algae

By: Bhaskar M V


Water pollution issues in ponds and lakes and solutions to these problems are in the news now a days for all the wrong reasons. Water pollution is increasing due to human activity – increasing population and consumption has resulted in more waste being generated – sewage, fertilizer run off, etc. These enter ponds, lakes, rivers, estuaries, etc., and cause algal blooms leading to low dissolved oxygen problems and fish kills and dead zones. The main source of ‘pollution’ of water is nutrients – Nitrogen and Phosphorus from sewage and fertilizer. Industrial pollutants though more toxic and harmful are a smaller problem in terms of volume. Farmers use fertilizer since plants require them, fertilizers cause higher plant growth and this is a good thing. Why are these fertilizers regarded as ‘pollutants’ when they enter a waterbody? What type of ‘plants’ grow in the water due to these nutrients? Micro algae i.e., Cyanobacteria, Green Algae, Dinoflagellates, Diatoms; macro algae, aquatic weeds, are the various plants that can grow in water. The problem arises when the balance shifts in favor of one group and this dominates the water. Thus when there is a large bloom of Cyanobacteria or Dinoflagellates the water turns Green or Red and some of these species release toxins too. Water hyacinth or Duck weed too can bloom and cover the pond or lake. Which is the best species / group of ‘plants’ to grow in water? How to maintain the desired ecological balance of various species? We believe that Diatom Algae are the best group of micro algae to grow, they are the best food for fish and hence do not accumulate in the water. Cyanobacteria / Blue Green Algae, Dinoflagellates, water hyacinth, etc. are not consumed by zooplankton, fish, etc. and hence accumulate in water and become a nuisance and have to be removed by artificial means – physically removed or by use of algaecides and weedicides. Diatoms on the other hand are removed naturally by Zooplankton and fish. Catching fish is easier and more profitable than harvesting algae. Diatoms typically dominate water during spring, early summer and winter. Late summer is when Cyanobacteria and Dinoflagellates bloom and dominate the water. The reason for this is that Diatoms require more inputs than other micro algae, they are the most recent of the micro algae to have evolved – less than 300 million years ago. Cyanobacteria evolved more than 3000 million years and Dinoflagellates about 1000 million years ago. Thus Diatoms are the more complex of all micro algae and they require many micro nutrients and Silica to bloom. Iron, Manganese, Zinc, etc., are the micro nutrients require by Diatoms. These and Silica do not dissolve easily in water. Metals oxidize in water and silica (sand) is not by nature soluble. Thus these elements are the first to be exhausted in water leading to the end of Diatom bloom in early summer and consequent domination by Cyanobacteria. Thus is supply of silica and micro nutrients is increased the Diatom bloom can be prolonged and the bloom of other algae and weeds controlled. N P K are the inputs that are common to all plants and algae, thus when these are consumed by Diatoms other plants are starved out. However, since Diatoms are grazed upon by Zooplankton and fish their population is regulated naturally and the bloom will not get out of hand if adequate number of fish are available and if the silica micro nutrient supply is regulated. Thus the natural ecological balance can be restored and maintained throughout the year. A solution to provide silica and micro nutrients in water in a stable manner has been invented by Mr T Sampath Kumar of Bangalore, India. He researched for over 10 years from 1994 to 2004 and perfected the formula. Its now patented and marketed under the name Nualgi [NUtrition for Algae] . Nano silica is used as a base for delivery of all the micro nutrients. Nano silica disperses in water and does not dissolve, however the dispersed nano particles behave in the same manner as dissolved particles. The silica keeps the metals stable in water and prevents them from oxidizing. Thus metals in Nualgi are stable in water for a long time and they are bioavailable to the Diatoms. The maximum dosage of Nualgi is 0.25 ppm i.e., about 1 kg in 1 acre of pond 1 meter deep. The Diatom bloom lasts for about a week, so repeat doses have to be given weekly. The cost of Nualgi used is fully recovered from sale of fish. 1 kg of Nualgi results in 100 to 200 kgs of Diatom biomass. This results in 10 to 50 kgs of fish biomass. 100 kgs of Diatoms give about 100 kgs of oxygen and absorb 137.5 kgs of CO2. Diatoms bloom rapidly and the color of water changes from green to light brown in a few days. When Nualgi is used in a pond with a massive Blue Green Algae bloom the BGA may crash within hours of the first dose. Nualgi is thus a safe and economical alternative to mechanical aerators, algaecides, dyes, etc. Bhaskar www.kadambari.net

How To Fertilize A Pond Or Lake


So, you have had a few problems with your pond or lake that seem to indicate that you need a little extra fertility. Maybe what tipped you off was:

  • Poor fishing
  • Skinny fish
  • Low fish population
  • Excessive pond algae like blanket weed or pond scum
  • Excessive lake weed growth

Whatever it was that tipped you off, you have come to the conclusion that something has to be done to increase fish production, get rid of lake weeds and pond scum, and prevent these problems in the future.

  • You have done your homework.
  • You have tested the water clarity of your lake and solved any problems related to soil particles in the water.
  • You have checked the pH and corrected it if needed.
  • You have water which is too clear to support aquatic life, so you know that you need to produce algae bloom, and you know that that means you need to fertilize your lake.

How do you fertilize a pond or lake?

There are several suitable methods for pond and lake fertilization, but let me start off with a few cautionary statements.

Liquid pond fertilizer

Liquid fertilizer should be mixed with water before being applied to a lake or pond. The liquid fertilizer will be heavier than the water it is being applied to, and will sink to the bottom where it will probably either be neutralized, or initiate unwanted plant growth.

Keep fertilizer clear of outflow

If you are using buckets or platforms suspended in the water to slowly dissolve fertilizer, make sure that they are not close to your spillway or drain pipe. This could result in the majority of your fertilizer ending up downstream.

Simple pond fertilizer method

If you are using fertilizer in plastic bags, you can lay the bag in shallow water, 2 to 3 feet deep, and slit the top lengthwise and across to allow the fertilizer to dissolve.

Fertilizer platform

If you are using a submerged platform, the platform should be about 1 to 2 feet below the surface of the water, and the proper amount of granular fertilizer can be dumped onto the platform and allowed to dissolve at it’s own rate.

Fertilizer in a bucket

The same result can be attained by suspending a 5 gallon bucket full of fertilizer with small holes drilled into the sides from a dock. be sure that it is one to 2 feet deep.

Fertilizer products formulated for ponds and lakes

There are a lot of newer fertilizer products on the market specifically designed for pond and lake fertilization that offer other options such as finely ground granules. These products come with instructions and label directions.

Special aquatic weed control note:

It is important to start fertilization early in the spring. If algae bloom is in place before weeds and filamentous pond algae have a chance to get started, this will decrease the amount of weed control needed for the pond. See also: Lake Fertilization

Using Barley Straw As A Blanket Weed Treatment


Everyone is looking for ways to accomplish jobs once handled by chemicals or physical labor in a more environmentally favorable, and less labor intensive way. One such treatment for filamentous algae (also known as pond scum, blanket weed, pond slime and other names) problems is the use of barley straw. Barley straw has been shown to prevent "blanket weed" or filamentous algae when used properly in ponds. It is thought that the decaying barley straw produces an enzyme that prohibits algae growth, but most experts will tell you that they honestly don't know exactly why.

What are the good and bad points of using barley straw?

The good side of barley straw treatment is that it is organic, and no chemicals are involved in the process, so there are no toxicity issues for fish or human beings, and that it seems to work fairly well. The bad thing about barley straw is that it is organic, and adding organic material to ponds is not always a good thing. To much decomposition can rob the water of oxygen, and add too much nitrogen. Both of these are bad for a pond. There are a few other issues. Barley straw may help to prevent pond scum, but it will not kill what is already there, and it may cause problems with the ponds natural life cycle if it destroys plankton. Plankton feeds the tiny creatures that feed fish, and without it, the fish go hungry. Furthermore, the destruction of the suspended plankton in the water will clear the water, something which unknowing pond owners desire, but which will allow light to reach the bottom where the pond scum starts, encouraging a new round of invasions from filamentous algae and lake weeds! The only way to keep pond scum from the top of your lake is to prevent sunlight from reaching the bottom of your lake, and that is accomplished best by healthy algae bloom. The same is true for most blanket weed treatments. An algaecide will kill algae indiscriminately, leaving no suspended plankton in the water profile. If the water is not more than 3 feet deep, and no follow up is done to produce algae bloom, the problem may come back with a vengeance! If barley straw is successful in preventing all forms of algae, there will be no algae bloom, or plankton to feed the small invertebrates that provide food for the fish.

When would barley straw be a good option?

The use of barley straw may be just the ticket if you want a clear pond with few fish, or if you want a clear pond, and you regularly feed your fish. The barley will need to be replaced periodically, and you may have problems with some aquatic weeds as a result of the water clarity issue, so be prepared to deal with them.

More natural methods

There are other ways to approach the problem of blanket weed. It can be prevented with algae bloom, which will further the life cycle. I know that it seems a little odd to use one type of algae to prevent another, but it is the best preventive method, and is perfectly natural. Most of the ponds and small lakes throughout the country are man made, and do not have the native fertility of natural lakes. In most natural lakes, the natural fertility allows a pretty constant algae bloom, coloring the water with a green tint, preventing light penetration to the bottom where the blanket weed and other aquatic weeds starts, and keeping the life cycle of the lake in operation. With man made ponds, in some areas, that native fertility may not exist. In such cases fertilizer may need to be added on a regular basis to acheive the same result. A good pond fertility program may be the most environmentally friendly and effective way of dealing with blanket weed. See also: Barley Straw Pond Algae Control: How To and Barley Straw Pond Algae Treatment Drawbacks and How To Fertilize A Pond Or Lake