| D O C |
| The foam that you see occasionally in the pond is caused by DOC, dissolved organic carbon. DOC is created by just about anything that is organic/protein in nature, such as, excess food, fish slime, fish waste, pheromones, fats, dead algae, etc., an overstocked system can also contribute to excess DOC. This is the same type of foam that you see at the beach or in a small brook. DOC is always in the pond but when it gets to a certain level it will start to form a foam, generally around the waterfall or anywhere else that the water is being agitated. What's happening is that the dissolved compounds are attaching to microscopic air bubbles, forming a film on them so they can't break, when the reach the surface. There are a number of ways to clear DOC from a pond… * Generally DOC can be seen on the surface of the pond as a film or a scum layer. If it's possible to overflow the pond then this film can be flushed away. * Large water changes to dilute it down * Regular use of Calcium Bentonite clay * Keeping the mechanical part of the filter clean and also the pond bottom * Potassium Permanganate can oxidize it away…Caution should be used when using PP or you'll have dead fish…read up on its use. They use of De-foamers isn't recommended as they generally don't work for any length on time and the DOC is still within the system. Graham Hawkins |
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