Hi, is blue green algae considered to be a serious problem. what I mean is
if it gets into an aquarium does that mean that a blackout or blackouts must
be performed to remove it from they aquarium because of the speed that it
spreads at and the lack of a working treatment in the UK.

I have had blue green algae in my aquarium since I first set it up in
November last year. it started as a small patch on the gravel in the front
of my tank and very quickly spread over the plants and gravel forming into
sheets. I removed the sheets and gravel cleaned weekly but it did not stop
spreading and the algae was back in force every three days or so.

I have a standard juwel 180 aquarium with zero ammonia nitrite nitrate 1ppm
phosphate. I have also lowered the phosphate with rowaphos to 0ppm for two
months. they only effect that had on the blue green algae was to reduce its
growth rate to a quarter of what it was. that also stopped nearly all plant
growth in my tank. a blacking out the aquarium for four days while the
phosphate was at zero also did not work

I have tried using blackouts several times. I tried a three day and a four
day blackout. each time the algae was not visible after a few days. but
returned a week or so after finishing. I then tried a six day blackout this
also had the same result. recently I tried a four day blackout followed by a
three day blackout two days later, I also started using interpet blue green
algae treatment a couple of weeks before. that has also not worked and the
algae returned after nearly two weeks, a few days ago, low down in the
gravel at the front of my aquarium. I put it down to the fact that a small
amount of light might have been getting to the gravel there, and have
started another four day blackout but i may try a seven or eight day
blackout in the hope of finally getting rid of the problem once and for all.

I have been using tin foil to blackout my aquarium with a towel hanging down
the back to help keep out the light that goes through the hagen picture
background at the back. I have also been covering all of that with a
sleeping bag except on this occasion were I have used extra tin foil along
the bottom of the aquarium. that gets it pretty near dark in the aquarium.

any ideas would be greatly appreciated!