There are a few factors that can start the growth of algae in your Biosphere:
1) The Nitrate Level is high, Nitrate encourages plant/ algae growth,. Check your plant and make sure that it is still a vibrant green. If the plant has died, it isn't filtering the nitrate as it should.
Another reason is the water in the tank has levels of chlorine. In this case, always remember to use Distilled Water, do not use regular tap water to fill your tank when doing a water change, chlorine is very harmful to ADF. You can also use a method of a Dechlorinated solution. It can be bought at most pet stores or aquarium stores. We recommend Prime.
2) Too much natural sunlight (not an electrical light for the tank), Direct sunlight is algae's best friend. Move your tank to a darker area. You may also use a blanket to cover the tank for a week and it will kill algae.
Easy steps to eliminate algae in your tank:
1. Remove enough water to access the algae growing on the side of the tank- try not to remove more than 50% of the water in the BioSphere. Use a turkey baster or similar water extraction tool to suck out any left over food or gunk lingering on the colored gravel. Do not remove the gravel or sand from your BioSphere.
Take a paper towel, napkin, or tissue and wipe the insides of the tank removing the algae. You might need a razor blade if it won't easily wipe off. Remove the 3 large rocks and give them a good scrub under running water. Remove the plant and rinse under running water as well. Replace the plant and 3 large rocks.
2. Cover the tank with a dark blanket or towel to eliminate all light to the tank for a week. This will remove the "food" for the algae.
If you have tried the above mentioned and you still have algae,
3. Purchase API Algaefix liquid. Use one drop for our classic size BioSphere and 2 drops for our gallon size BioSphere. Follow usage instructions on the bottle. Please note, this does not clean up the algae, you will still need to do step 1. This will only prevent the growth of more spores.
4. The last step would be to replace your biosphere. We do sell replacement tanks on our site. When setting up your new home for your frogs, do not move anything over from your old tank aside from the frogs. It only takes one algae spore to start the spread all over again. If you have a hide-away in your tank, boil it for 20 minutes to kill the algae spores before adding it to your new tank.