Acrylic aquariums come in a variety of sizes and shapes; they're also lighter than glass tanks, making them popular choices for home fish habitats. Algae can grow on plastic walls just like glass. A little bit of algae is normal, but you want to be able to view your fish through clear walls instead of a green haze.
Many types of aquatic creatures can help maintain the algae in your fish tank. Snails and shrimp will help keep algae off the walls, decor and gravel. bristlenose, hypostomus and farlowella plecos are catfish species will help keep algae between the plant foliage to a minimum. Loaches, Chinese algae eaters and common plecos will eat the dead plants, fish waste and excess food that fall to the bottom of your aquarium. Mollies and platies aren't the best algae eaters, but they will peck at certain types of algae.
If you don't have any live plants, add a few to your aquarium; if you already have live plants, add a few more. Live plants help use up the resources algae need to thrive, so the algae literally starve to death before they have a chance to overpopulate your aquarium.
Algae magnets work great with acrylic and glass aquariums that have square corners and flat sides; if your aquarium is curved or rounded, these magnets aren't the best option for ridding the walls of algae. The magnet has two parts; one goes on the outside of the aquarium and the other part goes on the inside. The magnet affixed to the inside wall has a cleaning pad; when you move the outside magnet, the cleaning pad attached to the inside magnet cleans off the aquarium wall. The outside magnet has a felt pad so the outside wall doesn't get scratched. You can purchase aquarium magnets at your local pet store or online.
Scrub the Walls
You want to use a sponge or scraper made for cleaning plastic. Your local pet store should offer a rubber-type scraper for acrylic aquariums, as well as sponges. Gently scrub the walls of the aquarium to knock the algae off the walls and onto the bottom of the tank where you can siphon it out with an aquarium gravel tube and where your algae-eating bottom feeders can eat whatever gets left. Razor blades will scratch the acrylic, so do not use them to clean off the walls of your tank.
Tips to Reduce Algae Growth
Do not overpopulate your aquarium. The more fish you have, the more waste they produce, which increases the odds of algae growth.
Do not overfeed your fish. Excess food sinks to the bottom and will foster algae.
Do not place your aquarium in direct sunlight. The sunlight will boost algae growth.
Regularly clean the aquarium. Partial water changes and siphoning the gravel or sand on the bottom of the tank will help remove excess waste, minimizing algae growth.