Algae in A Pond | Green water and Blanketweed
The single most common problem faced by pond keepers is the cloudy water pond
Yet the solution is permanent and simple.
Symptoms
This cloudiness is almost invariably the result of algae growth and is the reason the problem is worse in Summer than at other times of the year. The water is murky often quite bright green (like pea soup) although some algae are brown.
Water can be changed and after a few days the murkiness normally returns a sure sign of algae.
The cause
Algae are plants. Algae therefore need food and oxygen and sunlight to grow and survive. Like most of us the more food, the more oxygen and the more sunlight the better and bigger the algae grow. In the right conditions the algae grow at an explosive rate - 30 times per hour!! This is why your swimming pool can be perfect one day and the next day it is totally green. You say to yourself how is this possible? - now you know why.
Not all algae are green and not all algae are minute in size and nor do they all remain suspended in water giving that pea soup appearance. Some algae join together and create long slimy stands but the water is perfectly clear. Other algae grow to about 1 to 2 cm in length and stick to pond surfaces, waterfalls or rocks etc.
We will talk about these 3 general types.
It is not necessary to give the latin names and species. What is important is the practical understanding of the situations you will encounter.
A. First of all the usual problem of green water (sometimes brown) which does not go clear and even after changing the water the algae re-appears very quickly and this happens even if you have a filter installed perhaps.
B. Green/brown cloudy water is normally caused by these millions of algae remaining suspended in the water. Each algae is about 4 microns in diameter (1 micron is 1 millionth of a metre or very very very small).
C. The reason why algae is not removed in many filters is due to its small size - if the medium in your filter has gaps/pores greater than 4 microns in size then the algae will just get recirculated. By the way most filters suffer from this design problem.
D. Algae growth is most common in ponds where conditions are most suited to their requirements - lots of fish being fed lots of food, warm water as it is in summer here, and strong sunlight. The waste products from fish eventually create nitrates in the water and most pond food contains phosphates and lots of nitrogen. These are fertilisers for plants as you know from general gardening. Equally they are fertilisers for algae - remember algae are plants.
E. If there was no nitrate and phosphate there could be no algae. This comes back to Valerie's question. Even though Valerie did not have fish she had algae so where did the food come from. It came from the tap water almost certainly. All tap water contains nitrates and in some areas probably phosphates. Also wind blows debris into ponds and water features and these debris also contain these substances.
How to remove the algae
We must unfortunately accept that even in the best ponds algae will always be a threat. By far the best way and it works every time for this type of algae is to install a CORRECTLY SIZED UV light before the filter. This works very simply. The algae pumped through the light (and only those pumped through the light) are killed by exposure to UV light. Upon dying they clump together becoming much bigger than 4 microns. Because they are now much bigger this means most well designed filters are able to remove the dead algae. In all likeliehood the algae are still forming in your pond but they are being killed by the UV light FASTER than they are forming.
It is important to remove the dead algae in a filter because if they are allowed to sink to the bottom of the pond they can pollute the water quite badly.
You can learn more about UV lights by going to my web site http://www.garden-ponds-algae.com
When a pond is badly infected by green water then your fish can all suddenly die and this happens overnight normally. The reason is again simple and is because algae are plants - they produce oxygen during the day (in the photosynthesis process) but they produce carbon dioxide at night by taking oxygen out of the water. Algae in large mass can totally deplete the oxygen from a pond. The fish therefore suffocate. This is also very much more common in heat wave situations like we are presently experiencing because at higher temperatures water can hold less oxygen anyway.
Algae can be controlled by using any algaecide but read the instructions and beware of environmental problems. One of the best because it totally harmless to all wildlife and plants in water features is Biotal ALL CLEAR. These products are also effective in ponds but have to be used continuously and are thus very expensive cures over a period of time.
One of the very best inventions in pond keeping was the UV light.
B. Algae that grow to about 1 cm in length and are seen on pump surfaces, rocks, pump filter sponges and the sides of ponds are normal. Do not try to remove them by sweeping the pond walls for example because they will keep coming back and if left alone reach an equilibrium point. The fish love them and the balance of the small pond is improved.
They can be a bit unsightly sometimes but this is natural. They will not damage your pond environment. A UV light will not effect these algae in any way because they stay in one position and are NOT exposed to the UV light.
The enigma of blanketweed.
Blanket weed is that long slimy algae that seems to grow and grow and can never be eradicated. Many pondkeepers never see it and others are never without it. It is an area of pondkeeping not well understood and many of the suggested solutions do not always work. UV lights are no good because the algae is not exposed to the light - it remains in the pond.
Often even when there is lots of blanket weed the water is crystal clear. This is because the blanketweed is starving other algae out of existence.
Water quality certainly plays a role in blanketweed development but this is not the whole story since even the best pondkeepers can get this problem.
By improving the balance between plants in the pond and reducing fish density and therefore reduced feeding the tendency to blanketweed will be reduced but not necessarily eradicated. Plants in ponds compete with the algae for the "fertilisers" produced by the fish as explained earlier.
Recent product developments particularly around barley straw products have been.
Be careful when buying chemicals to kill blanketweed - make sure they do not kill anything else including plants, fish, filter bacteria, birds that drink the water etc.
Koi and goldfish like warm water and summer weather. They eat more food and they create more waste. Algae and plants also like it. The plants grow more quickly and there is more food from the fish waste.
The result is that algae problems will tend to be far worse than you might remember. However remember also that it is impossible to stop algae forming in a pond environment - THIS IS NORMAL AND NATURAL. All you can do is control the amount of living algae by using an UV for example.
The practical implications are that you will need to clean your pump sponge more frequently and maybe also your main biofilter.
Algae on the sides of a pond (up to say 2cm long) or on the stones in a pond is GOOD and NORMAL.
Blanketweed is a curse ... I recently discovered the final solution. take a look at this new website that I created ... all about blanketweed and string algae.