How to Prevent Algae in a Planted Aquarium

Removing algae is a hassle. This artile will tell you how to prevent it from ever becoming a problem. The most important thing to understand is that plants are more highly developed and, under the correct conditions, will always outperform algae in their consumption of nutrients and growth. The best way to control algae is to take the right steps from the beginning, but it is never too late! This article will focus on prevention of most types of green and/or "black" algae (not red or brown algae, which is not actually algae).

Difficulty: Moderate

Instructions

Things You'll Need:

• the appropriate light intensity (see note on light below)
• algae eating fish and snails
• access to Reverse Osmosis (RO) or distilled water
• micro-nutrient plant fertilizer (usually sold as "comprehensive" or "trace" elements)
• macro-nutrient plant fertilizer (there are only four: Nitrogen, Phosporous, Potassium, and Iron - see note on Iron below)
• carbon fertilizer or carbon dioxide gas (see note on carbon dioxide below)
• mineral salt mix (NOT sea salt or regular salt; usually marketed as "R/O Right" or some other similar name)

1. Determine the appropriate intensity of light and install it. Add up the total watts of light you have and divide that by the total gallons of your aquarium. Here is the general rule of thumb: dark green plants need only "low light" (1-2 watts per gallon of water); light green plants need "moderate light" (2-3 watts per gallon of water); pink/red/brown/bronze plants need "strong light" (3-4 watts per gallon of water). Too much light for your plants will produce algae; not enough light will kill your plants! Keep the lights on as close to 12 hours per day as possible; consistency is the key!! Direct sunlight will always contribute to algae.

2. If you are first starting your aquarium, add as many plants as you can from the beginning. They will always take up more nutrients than any algae and thus slow any algae growth. If you have already have lots of algae, physically remove as much as possible (pressure washing is easy for rocks and wood). "Algae-killers" are useless (see warning below).

3. Add a "clean up crew" that will eat algae. Siamese algae eaters eat hairy-looking algae (even the black kind, the only ones that will!). Ottocinclus cats eat flat, bright green algae. Olive nerite snails will not eat plants, will not reproduce in freshwater, and will eat bright green aglae also. Regular plecostomus (pleco) will eat most algae but will also grow excessively large. NEVER use apple snails. They eat plants.

4. Remove half of the water in the aquarium each week (bare minimum every two weeks) by using a siphon. Refill the aquarium with water labeled as "Reverse Osmosis" or "Distille" (NOT bottled water). This water can be purchased at the local aquarium pet store or at a supermarket. (see tip below)

5. Follow all instructions on each bottle of fertilizer carefully. Add the micronutrients, each macronutrient, the mineral salts, and the liquid carbon fertilizer (unless you use carbon dioxide gas) directly to the new water and mix well. (see warning below)

6. 
   a good visual summary of how to diagnose nutrient difficiencies

   Carefully monitor the coloration and appearance of the plant leaves. If you notice yellowing, browning, holes, or unusual decay, it is likely due to a nutrient imbalance that should be corrected. If you are using carbon dioxide gas, carefully monitor the flow to ensure that it is not too high nor too low. Between 15-25mg/L CO2 is recommended for optimal performance. (see warning below)

Tips & Warnings

• conrolling the amount of time your lights stay on is a cinch with an inexpensive light timer!
• Using RO or distilled water is superior to tap water because tap water is made specifically so that plant life will not survive in it; that is why it is safe to drink!
• In a heavily planted tank cleaning the gravel is not necessary (just the debris on the surface). Weekly 50% water changes are necessary to remove unused nutrients that would then 1) feed algae and 2) eventually inhibit plant growth the "left-overs" would build up.
• Iron: this will have to be supplied only if your aquarium does not have special "plant gravel" such as laterite, "Eco-complete," ADA soil, etc. Regular gravel will not supply any nutrients to your plants and they will "starve."
• carbon fertilization: No matter how much fertlizer or light you provide, if your plants cannot "breathe" then they cannot thrive. Liquid carbon fertilizer is the simplest method, yet over time is the most expensive. Using a pressurized CO2 gas has a high initial cost, but is the most cost effective over time and provides maximum growth potential.
• Lights MUST be the correct spectrum (as your dealer) and MUST be replaced every year, because the spectrum will change to one that the plants can no longer use...you will only be growing algae.
• DO NOT overdose or underdose your aquarium with fertilizers. Plants will use different nutrients in different amounts. Simply "dumping" them in will never change how much of a nutrient a plant will consume; it will only result in more "leftovers" that then become food for algae!
• If you must trim your plants when they are overgrown, and if you use pressurized carbon dioxide gas, you must remember to turn down the pressure to accomodate the loss of plant mass; otherwise you might have dead fish from carbon dioxide poisoning!
• Most "algae-killers" are ineffective at preventing the return of algae; they only kill what is already present. Many of them also contain phosphates which is a food for algae, so if you must use one make sure it is phosphate-free. REMEMBER, if it can kill a lower plant life-form, it could also harm your plants!
• DO NOT overfeed your fish. Excess food will create excess nutrients, which will feed algae. All food should be consumed within 5 minutes or removed. Feeding once per day or every other day is sufficient for most tropical fish.

Resources

• Tom Barr, Planted Aquarium Expert