Hi all,

Any help would be much appreciated...

I'm having problems with the rapid build up of green algae, a thick layer of slime that covers the whole of the aquarium base, after a matter of days.

I have a 160 litre tank, fluval 304 ext. filter, all the correct media, 15" air stone, and heater set at room temp. for those cold winter nights.

I have a single inhabitant at present, a Comet goldfish.

Have tested for amonia and nitrite and is ok, although pH is slightly alkaline at 8.5, and might explain the rapid build up. But how do I change this?

Help much appreciated...

Kev...

Hi,
Algae build-up is dependant on Nitrate and Phosphate levels; temperature, pH, hardness, and dissolved oxygen readings; as well as light intensity and duration, which is why it's one of the worst problems a fishkeeper faces - the causes are really complicated!
As for your set-up, I would need to know a bit more about the readings I specified above - nitrate is the main one in freshwater tanks. If this is above 50 parts per million, then that could be your problem, and the solution is much less food and a few decent-sized (30-40%) water changes over a period of a few weeks (assuming your tapwater is low in nitrate). Otherwise, it could be your light period - often, algae can be cut right down by having a dark period in the middle of the day (i.e. turn the lights off for about an hour at lunchtime or thereabouts). The light shouldn't be on for more than 12 hours a day - 9 or 10 is more accurate for coldwater tanks.
Algae has always been a bane of aquarists' lives, so don't despair - persevere and you will beat it!
Good luck!

Hi,

Thanks for the reply... ok, some tests done today...

Amonia - 0.1 mg/l
Nitrite - 0/0.1 NO2
Nitrate - 75/100 NO3
Broad Range - <8.5 pH

I notice that Nitrate level is higher than would be hoped for, but others seem to be acceptable. (I think!)

Have reduced light time now, didn't realise this was so effective. Will get a timer to aim for 10 hours during day, with an hour break as u suggest. In the past have had in excess of 12 hours.

Thanks for your help... any feedback much appreciated.

Kev...