
Originally Posted by
altec
the greenish color is plankton. It requires several things to grow: organic matter, photosynthesis, and oxygen. Since its a fishpond, then it will be under the sun, so you have no choice with photosynthesis. Oxygen, no choice, as your fish needs it also. Organic matter, it is normal, especially when you put in fish and you feed them, and they make pupu.
Options to control the bloom:
good filter system that includes filter brush to remove the big particles, filter mat to remove the fine particles, gravel to provide some filtration and biological action, and for more sophisticated filters, uv filter setup. Preferably the pump is on all the time. But in my case, I switch it off 2 times a day to save on electricity, assuming that you don't have too much fish that will cause them to surface if you don't run the pump. There are some aquatic probiotics that will also help eat the organic matter, one of the things that builds up through the nitrogen cycle and causes the plankton bloom. The use of shade, such as those orchids black net is also helpful. Or provide direct cover during direct sunlight and remove them during that time of the day when the sun is on the other side.
Do not overfeed (but in your case, wala pa nga isda, may green color na).
Take note that even the slightest organic matter will be enough to create that plankton bloom especially with us being a tropical country and the lovely sun beating down on us.
By the way, janitor fish or scientifically names plecostemus, which is the fish now the infestation of laguna de bay, eats selected waste only and does not help in preventing bloom.
When your water has developed bloom, best way is to replace all the water. Yes, all of it. Changing part of the water keeps some of the plankton in your system, and acts as seedstuff for more plankton development.