My 10 gallon fish tank has recently developed a problem with algae growing on the glass, plastic plants, and rocks. I have done water changes, changed the filter, and have been treating the water with Tetra Algae Control but the algae just keeps reappearing. I'm not sure what else to do so any help would be great!

Also my fish (koi) seem to be acting strange. I don't know if this has anything to do with the algae in their tank or not. They freak out for no reason and will swim as fast as they can into the glass or will jump out of the water. They also swim very close together all the time which is something they haven't done before...

If anyone has any ideas or suggestions as to what is happening in my tank your help would be greatly appreciated.

Algae growing in the tank is OK. It doesn't mean anything is wrong.
You might have the tank in a place where it gets too much sunlight
Or perhaps you're leaving the lights on too long.

To control algae, all you need to do is buy an algae scraper to clean the glass with.
They make handy magnet ones that work really well.
Also, wash the plants and décor in warm water and reduce running lights to a minimum or move tank out of direct sunlight.

The darting, jumping out of the tank and sticking close together that you describe sounds like a problem.
They might be sensitive to the algae killer and it could be burning them.
I'd advise to dilute the water with fresh water.

Most algae killers lower oxygen levels in an aquarium too.
If you have a hang on back filter, lowering the water level a few inches will allow the water entering the tank to create lots of bubbles
Which will put lots of oxygen in the water for the fish while they recuperate.

I would cut the water in half today with fresh water and not add anymore algae killer.
Keep the water level a couple inches below the top if you have a hang on back filter.
Watch them closely for signs of distress.
Look at their bodies and see if they have any visible signs of disease.
Since some fish are sensitive to algae killers, when using them, only use a forth of the recommended dose as a preventive.

Also, just a note, algae killers take weeks to work.
So even though it is added to the tank, you will not see results right away.

This sometimes fools people into adding more of the product which harms the fish or they do extensive cleaning that
Isn't necessary... which can also damage the aquariums cycle.


Good luck to you!

Thanks!