algae

Algae can be found in just about any enviroment on earth, from lakes to oceans to mountains to within the snow that is in your front yard. They can range in size from a single microscopic cell to the giant kelp of the Pacific Ocean. There are six taxonomic divisions that are further divided into classes and so on down till you have literally thousands of species. Algae comes in many forms from floating to anchored or attached and in many different colours…green, brown, red, blue and just about any shade in between.    Luckily for us we only have to deal with a few of them.
Within our ponds and aquariums, the ones that we have to deal with the most are:

* Green water- Phytoplankton- single cell green algae that just about everyone has experienced at one time or another. All ponds or aquariums have this alga within them, all the time, but when conditions are right, it starts to reproduce to the point that the water appears green. This usually happens in the spring when the filter bacteria are not functioning at their peak and nutrient levels are high. The amount of sunlight that the pond receives has little to due with an algae bloom. It takes very little light for the bloom to continue, so the use of covers will have little effect. There are a number of ways to control green water, with an Ultra Violet lamp being the easiest. The light emitted from the UV disrupts the structure of the cell as it is flowing by, thus killing it. The use of a proper sized unit, the larger the better, and the pond water flowing past the bulb at least every 2 hours will keep a pond clear. Unless UV's are extremely large they do not effect bacteria flowing by them. Controlling the nutrient levels, nitrate and phosphate, within the pond will also help you get rid of green water, one way this can be accomplished is with the use of floating plants to compete for the food. The best way is to have a fully functioning bio-filter.

* Hair, Mat, Blanket- there are a number of different kinds of algae involved here but they all kind of look the same, just in varying lengths, usually shades of green, that wave in the water column. The longer they are, the more of a nuisance they can be. Some, when the filaments get long enough, break off from their base and float on the surface and clog most everything. A lot of the time you'll see ''little diamonds'' on the strands, this is oxygen that is being produced through photosynthesis. The shorter varieties form nice fuzz on the pond walls and provide additional food for the fish. These should not be killed off. There are a number of ways to control filament algae, one of the easiest is to use your net or a brush or a broom to scrap it off the sides and physically remove it. The use of salt or Calcium Bentonite, lightly sprinkled around will help kill it, but water qualities should be monitored till it's been filtered out and removed from the system. Dead, decaying algae creates ammonia. Again, fully a functioning bio-filter and the control of nutrients within the water, is the best control.

* Brown – a light golden to brown film that will coat most everything within a pond or an aquarium. This alga usually shows up in low light, low nutrient water and at lower temperatures. An excess of silicates in the water will also contribute to these diatoms. Diatoms are single cell algae that have an external shell made out of silica. This is where diatomaceous earth comes from that is used in swimming pool filters and some aquarium filters. A well cycled filter and higher light levels will usually make it go away.

* Blue-green- algae is often mistakenly classified as algae because of the chloroplasts contained within the cells. These organisms are actually photosynthetic bacteria. The proper term for this group is Cyanobacteria. This type of "algae'' can form mats over just about anything within a pond and choke it out. Blue-green alga is commonly seen in salt-water aquariums.

      Algae need several basic things to grow and flourish…food, sunlight, temperature and carbon dioxide. The food that it uses is mainly nitrate and phosphate. The nitrate is mainly produced as an end product of the nitrogen cycle. There may also be nitrate levels within your tap water that contribute to the level when water changes are done. This is one of the main reasons, not to do water changes, trying to clear the pond. It generally doesn't work or only a short period. Phosphate is also introduced through a similar process and through heavy feedings and high fish loads. Keeping fish loads and feedings to an appropriate level for the size of the pond will help keep the phosphate down. Keeping the interior of the pond and the mechanical part of the filter clean will go a long way in helping keep these levels down.

      Sunlight and temperature can be controlled in hot/ sunny climates by the use of a shade canopy. Needless to say this should be kept well up and away from the water's so as not to create a green house affect. The warmer it is the more algae likes it. C02 levels can be kept down by simply having a well running waterfall or fountain, which is on all the time.

      Rain water run off from lawns or gardens should never be allowed to enter the pond. The fertilizers that are used can add greatly to algae's growth…you already have 2 of the ingredients there, nitrate and phosphate, why add more. Another thing is if you're using a spray fertilizer, such as Miracle Grow, wind drift can carry it into the pond, so be careful with its use on windy days.

      One of the ways too control levels is to have large numbers of floating plants in a ''Veggie Filter" which will compete for these nutrients, eventually starving them all but out. These plants should be located in a separate pond or protected so that the fish cannot eat them. Plants in soil will have little effect on nutrient levels as they get their nourishment from the soil and not the water. Plants such as; Water Hyacinths, Parrots Feather, Azolla and Duckweed will give the best results. The use of fertilizer tablets for Water Lilies can also add to the nutrient level of the pond. Care should be taken in their use. Plants that are dying should be removed as soon as possible, as they rot they release the captured nutrient back into the water.

     The use of Trickle Towers seems to drop the nitrate levels within a pond, no one really knows why…some think that it's a third type of bacteria utilizing it and turning it into nitrogen gas, others think its just the high levels of 02 within them gassing it off. Whatever it is, it seems to work. A lot more information on TT's and their use can be found on the web .
     There are a number of different products on the market for absorbing nitrates or phosphates, but most would be too expensive for the volumes of water in a pond, therefore, they are not practical. There are also a number of products on the market for killing algae, Algaecides, or for clumping it together, Flocculates, so the filter can remove it. Yes, they do work to a certain degree, but they upset the balance within the pond. They kill all algae, even the good ones that you would like to keep. They get rid of the symptoms but not the underlying problem, too much nutrient.

    Algae do consume toxic elements in the water and help balance the system, so some should be allowed to grow. Once dead, these algae's start to decay, creating ammonia problems and releasing the nutrient they had captured back into the water. Oxygen is also used up in this decaying process. Flocculates clump the algae together so that the filter can pick it up. The problem with these products is that the amount of current within the pond is generally too great for the bond to last and the algae is dispersed again before it can be removed. Both these products still don't get rid of the under lying problem…too much nutrient.

    The other big problem with too much algae in the pond is the swings that happen to the pH and the oxygen levels. During the day the algae uses C02 and gives off 02 and that's a good thing. Then at night, it does the reverse and this is where a problem can occur. In heavily stock ponds the O2 levels can drop to the point where fish can suffocate. Turning off waterfalls, fountains, etc., can make this low O2 level worse. Never turn these off at night, whether you have an over abundance of algae or not.    The C02 that the algae and plants are releasing is turned into Carbonic Acid; this in turn is trying to drive the pH of the pond down. If the Carbonate Hardness, (KH, TA…the water's buffering ability) is not sufficient enough then the pH will fall. If the KH is low enough, then the pH will crash down into the 4.5 to 5.0 range, resulting in fish losses. PH's should be tested in the very early morning and then just after dusk, if there is a large difference in the readings then steps should be taken to correct it. PH should be kept in the 7.5 range or better level and KH should be in the 80ppm or better level. The use of Arm & Hammer Baking Soda, sodium bicarbonate, will raise both these levels and is not toxic to the fish.

      Your filter, once well cycled, assuming that it is sized correctly for the pond volume and the fish load, will develop enough bacteria to utilize most of the nutrients that the fish produce…you'll end up with a balanced system and very little algae.

      To summarize, a healthy, clean well-maintained bio-filter, the use of an UV, and proper fish loads and feeding levels and 30% water changes with low nitrate water, will control algae levels within the pond and you'll have nice clear water to be able to enjoy the fish.

Graham Hawkins

Algae