10 Ways to Control Algae

1 Frequent Partial Water Changes

In nature, rain and water currents refresh water conditions by diluting and carrying away nitrate before it can build up to excessive levels.  Your closed aquarium system, however, requires regular water changes to remove excess nutrients.  Ideal frequency is 10% weekly, but for a lightly populated aquarium, 30% monthly is sufficient.  It’s also a convenient time to siphon up all the sludge and dead plant matter in your gravel.

2 Feed Your Fish Sparingly

One of the most enjoyable times for the new hobbyist is watching the flurry of activity in the aquarium after that pinch or two of fish food hits the surface.  Sometimes there is a temptation to repeat the show 2-3 times a day, which is fine if your fish consume all the food within a couple of minutes.  The problems start if there is excess food, which is defined as “overfeeding.”  Overfeeding is the most common source of the algal nutrients phosphate and ammonia.  Algae thrive on both the nutrients generated from uneaten food and fish waste.  Many experienced hobbyists who learn to resist the feeding frenzy and only feed once daily – or feed smaller portions 2-3 times daily – find it’s much easier to keep the unwanted green at bay.

3 Test Your Tap

It is a good practice to test your tap water before changes, because it may contain algae-encouraging elements right out of the faucet.  If the test results show significant levels of phosphate or other algae inducing elements, your battle against algae will not be successful until those compounds are reduced by a tap water filter or a reverse osmosis (RO) unit.

4 Filter Media

There are different filter medias that are designed to remove phosphates, heavy metals, dissolved organics, and a host of other contaminants.  Choosing the appropriate media can help to combat even the most difficult cases of algae.

5 Control Your Lighting

If you turn on your aquarium lights when you wake up and turn them off before bed, the extended light cycle may be encouraging extra algae growth.  Put your lights on a timer to replicate the day and night lighting that occurs naturally.  Keep lights on for 10-14 hours per day for planted aquariums and 6-10 hours for ornamental setups.  The bulbs should be changed once per year at minimum because as they age, they lose their intensity and can encourage nuisance algae growth.

6 Increase Competition With Plants

The more plants in the aquarium, the less likely algae will take over.  Plants compete directly with algae for light and nutrients, and most often win if given proper conditions.

7 Stock With Algae-Hungry Catfish

Put some fish in your community to work on tank maintenance.  While many algae-eating Plecos grow too large for small aquariums, the Dwarf is just the right size.  This hardy worker seems endlessly busy – always seeking out any plant or structure with algae.  The Cory Cat, another small catfish, patrols the bottom of your aquarium, vacuuming up excess fish food before it can rot and turn into dangerous ammonia and nitrite.

8 Choose your weapons

Using magnetic scrapers on glass aquarium walls is an excellent way to remove algae and slime that attaches to the inside wall of the aquarium.  Scrapers are also available for acrylic tanks that do a good job as well.  Remember that acrylic aquariums scratch easier than glass aquariums. 

9 Know When Some Algae is OK

Take a step back and look at your planted aquarium.  Is it natural looking?  Is there a small amount of green covering driftwood or rocks which makes the structures blend in with the underwater garden?  If the algae is not covering the glass or choking out the leaves of your plants, there is little reason to panic.  Algae may be unsightly, but it actually consumes excess nutrients and provides oxygen.  Success is finding a natural balance in your enclosed ecosystem.

10 Know Your Enemy

Green Carpet Algae, which covers glass and structures is relatively easy to clean because we have the most weapons to combat it – algae scrubbers, algae-eating catfish and invertebrates.

Green Hair Algae is more stubborn, and even catfish and Plecos may avoid it.  Your best bet may be to pull it off.  Your best protection starts with water quality so you don’t have to roll up your sleeves later.

Beard Algae is the black scourge of planted aquarium hobbyists.  A major takeover by this unsightly guest may only be remedied by pruning away colored leaves and removing affected driftwood.