Why is my Betta tank suddenly full of algae after adding an LED light?

Algae is a constant in an aquarium. The smaller the tank the harder to keep it clean. Bleach will kill any fish you put in the tank after using it, and it will just come back anyway. Frequent partial water changes will help, but manually wiping the tank is the only way to keep it clean. An algae eater can help but usually not a good idea with a beta fish.

Brown algae overgrowth can be due to high nitrates, too much light or overfeeding. Use a liquid home test kit or submit a water sample for testing. Most pet or fish stores will do this for free of for a small fee. If nitrates are over 40ppm, it can be decreased by performing partial water changes. Use only aged or conditioned water that is temperature matched to prevent stress or shock. You can also use a nitrate absorbing filter insert. The algae will need to be physically scrubbed from plants or rocks and can be scraped from glass. Rinse filter media using tank water NOT tap water. Limit light to 6 hours daily, 8 if you have live plants and do not over feed.

The green you see is algae. These like nutrition-rich water and lots of light. So you are probably feeding your fish too much and they are not eating all the food. Also there may be too much day light reaching the tank. I suggest you cover your tank in such a way that most of the day light is removed. Fed your fish sparsely. That means, only feed what they can and will eat within one minute. Get some algae-eating fish like a small pleco. Also change about 1/3 to 1/2 of your tank water to remove some of the algae floating in the water.

Check the water chemistry using a home test kit or submit a water sample for testing. The local Petco may do this for free or for a small fee. Aim for an absence (0 ppm) of ammonia and nitrites with nitrates at 20ppm or less. Perform partial water changes to stabilize chemistry and/or to improve water quality. Rinse the filter media in tank water, not tap water, and replace it. Use only conditioned water that is temperature matched to prevent stress or shock. To limit algae growth, maintain pristine water quality via filtration and regular water changes. If possible, turn up filter flow to keep water moving. If this stresses the fish though, do not do it. Do not overfeed and remove any uneaten food promptly. Limit lighting to 8 hours daily and closely monitor water temperature as well. All these can promote algae overgrowth.

Hi, and thanks for your question. You can actually attach the pics to the question if you like. This description of the lesions could be compatible with a parasite or possibly a bacterial infection. Begin by submitting a water sample for quality testing. Most pet stores will do this for free or a nominal fee. Clinical examination should always include a water quality check, even if you have done so already. Water testing should be performed with a quality test kit, measuring NH4, NO2 and NO3. High ammonia levels, PH imbalances may be responsible for these signs. Oxygen concentration and quality of the filters should be determined as well. If water quality is good and there are no major imbalances, your fish should get examined to look for any sign of bacterial/fungal/parasitic infection and eventually water should be treated. Hope this answer was helpful, but please do not hesitate to contact us again on the forum or by requesting a consultation if you have any more questions or to discuss it any further.

Sand substrate is always a problem as it promotes decay and anaerobic bacteria. If you need sand in a tank for a fish species (none of the ones you mentioned above actually need sand) you should not use it in the whole aquarium , but only in a small spot to accomodate the fish. Rust-colored spots on the glass and gravel are due to diatom algae. They likely were brought in with the silicates in the sand.Diatom algae need the silicates to make a shell they carry around with them. Remove the silicates, and the algae should die. Removing silicates can be done with a silicate and phosphate filter, or, in your case, I would remove the sand completely and refill your aquarium with washed gravel. Algae also need lots of nutrients, so if you overfeed your fish, algae will increase. Feed only what your fish eat in one minute, no more.

Bettas do best in water temperature between 78 F and 80 F. An algae eater should be okay, but it depends on your individual Betta. Some don't mind bottom dwelling tank mates. Watch for signature of aggression and remove the algae eater if necessary.