goldfish aquarium

Question
QUESTION: How do a get green water to go away? My aquarium is NOT in sunlight,I do NOT keep the aquarium light on long & i feed my fish every 2/3rd day & it is only a small amount my fish get to eat.My local pet shop told me it was algi spores & recommended Easy Balance,i have been using Easy Balance for 3 weeks now & my aquarium seems to be gettin worse.Hope you can help!  thanks sharon.

ANSWER: Hi Sharon,
Green water algae is very easy to fix.  People at local fish stores never really know what they are saying.  Their job is to get you to buy things.  All you have to do is cover your fish tank and make it pitch black for 3 days.  It is called a "Blackout method".  Some people cover it with towels, some people use black trash bags.  However way you do it, it has to be completely covered for 3 days.  However no feeding is allowed, the fish will be ok, they can withstand no feeding up to 2 weeks.  There is one thing you have to do before doing a blackout which is a water change.  The reason is, during a blackout, all the algae dies and turn into nitrate.  To prevent nitrate toxicity, do a 50% water change before a blackout and another 50% water change after a black out.  Your tank will be clear right after the blackout is over.
-Matt-

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QUESTION: Hi matt its sharon here. I did wot you said with my tank to get rid of green water algae and it is not totally clear yet. Is there anything else you can recommend please?
Sharon.

ANSWER: Is it not clear due to the algae or just murky water?  Did you cover the tank completely?  No light whatever should be allowed to go through.  Sunlight can still penetrate towels for example.  So more than 1 towel will be needed to make it pitch black.  It should work, but if it doesnt, there is a UV filter that can cure that problem also.  However it is quite costly.
-Matt-  

---------- FOLLOW-UP ----------

QUESTION: Hi my tank is very clean and the water has been changed, i put a black binbag over it along with a beach towel and it was totally covered. do u recommend for me to try it again with extra towels over it?
Wot kind of filter would you recommend for a 35 litre tank?
Sharon.

Answer
I would try it agian, but make sure it is pitch pitch black.  Add more towels, or if the tank is small enough to be moved, move it to a dark room.  No light should enter.  Even the smallest amount of light can fuel this algae.  However, I would feed the fish first then redo the blackout.  If you are keeping live plants, then temporarily remove them, as the blackout method is harmful to live plants.  The UV sterilizer filter is $50 and up, and is up to you if you want to use it or not.
-Matt-