i have had the same 3 goldfish (100mm) and the same filter for over 15 months with no problems. Filter is 300litres/hour, tank is about 120 litre.
Why a sudden bloom of green algae after three days. The filter wont pull it out of the water. In the past tank was cleaned about once a month.
Ive got the same problem with my axolotl tank, it is the sun. The tank is in quite a sunny room and as a result is full of green alage after like three days from its last clean. it normally doesnt do it but has been starting over the last month of so so my guess is that it has to do with the seasons of sun position of something. However you can buy products like for my tropical tank i use Algafix but im not too sure about cold water
Good luck with your tank
Tasha
Filter floss packed fairly tight will pull it out of the water, as will a diatomaceous earth filter. Depending on just how green the water is, you may have to replace the filter floss or the diatomaceous earth powder within an hour the first time, and then the new filter media should last longer each time it is changed.
pets question and answers,www.5d2d.com Leaving the green coated filter media in the filter is a bad idea. The algae or euglena making the water green will die and release the nutrients the remaining green water needs to grow back. Plus the filter might clog.
Is the tank getting more sunlight with the season changing?
You have free floating algae in the water, the most common cause is too much light. Keep up the water changes, to reduce the nutrients in the water, and reduce the amount of light the tank is getting.
Ian
You might have too many fish in that size of tank. I used to have four gold fish in my tank, and the water would get very green quickly. Now I only have two and I rarely have to change the filter.
Could also be sunlight, or the heat of the room.
