my 20 gallon tank keeps turning green help

my 20 gallon tank keeps turning green help, it is a knew tank had 10 gallons before and never had this problem. 2 fish disappeared have 4 frogs in though

where do you keep in your aquarium?does our aquarium get direct sunlight?if your tank gets direct sunlight then your aquarium will be affected by algal bloom..use a magnetic scrabbler to remove it and best that if you don't keep your tank besides direct sunlight...

algea is normaly caused by to much light or over feeding or both, id reduce the amount of light and go easy on the feeding for a couple of days another alternative is live plants, they will use up all the good stuff the algea needs to thrive

Thank you for your answers. I change almost all water like 3/4 then added the chemicals petco gave me kept light off and put a black sheet over it. My tank does get alot of sunlight I have two windows in where it is but I dont feel its direct light.

ok,using a magnetic scrabbler will be a good idea if you find that green spots on your glass..

Adding a bunch of chemicals usually doesn't improve much of anything. In fact it can kill beneficial bacteria and produce dangerous, rapid changes in water parameters. In addition, changing 3/4 of the water at once can change water parameters too quickly. You should at least be sure the replacement water temperature is very close to that of the original aquarium water.