Real-life Problems with Algae
by Ruby Bayan
Problems with algae are some of the most common concerns I hear about. Below are actual questions posted by our visitors, followed by my suggested solutions.
~ Green Water ~
Question: I have just performed a water change to my 230l tank, and the water has turned into a greenish hue. Nitrate levels are okay, I tested them. Could you tell me why this has happened? Will it harm the fish? - Therese
Answer: Hi Therese, green water doesn't harm fish -- and some people actually like the color. It's an algae bloom. You may be exposing your tank to too much light. And there's enough nutrients in the water to feed the algae. If you don't like the greenish color, you can reduce the lights a bit, do another water change, or add plants to absorb the nutrients that feed the algae. You may also want to consider using a diatomaceous filter (see our filter articles).
Follow-up Question: I still have that green water problem which started about 2 weeks ago. I have been keeping the neon light of the aquarium off, and I have performed a 50% water change, but the water is as green as ever. I can hardly see the fish. I am considering using a green water treatment. I have heard that this could be harmful to the fish. What is your opinion of this? Should I add some live plants, although my fish make a meal of these? -Therese
Follow-up Answer: Hi Therese, here's something a bit radical -- daphnia. These are minute crustaceans that are actually a favorite of fishes. If you can find a supplier of live daphnia, they will eat off your green water in no time -- that is, if the fishes don't eat the daphnia first. :) Yes, live plants are always a good option because they absorb the nutrients that the green algae will otherwise thrive on. And, this is just me, but I've never liked using "chemical treatments" for algae.
~ Brown Algae ~
Question: I have a well established 6 year old temperate goldfish tank. It is a 29 gallon acrylic with a aqua clear 300 filter. I have 4 oranda gold fish and 2 black moors. In the past i have had an algae issue that has since been taken care of but now i have a brown sludge like fungus growing constantly in my aquarium. It got my fish sick and i gave fungus medication, cleaned the tank very well and have been feeding every other day rather than every day. i do about a 30% water change every week and the fungus (?) keeps coming back. My question is how do i get rid of it and is it even fungus or am i going about taking care of it the wrong way because its not what i think it is. thanks, AP
Answer: Hi AP, I have a suspicion that you're dealing with brown algae. Goldfishes are notorious for polluting the water. It's possible that your filter and water changes are not able to cope with the waste products they produce. These waste products are food for algae; add to that a low-light situation, and you have the perfect habitat for brown algae (diatoms). Just vacuum them off and try raising your illumination level a bit. I know it's tricky because too much light will encourage green algae. Have you considered adding plants?
~ Red Algae ~
Question: Hi, I have 55g tank and have recently introduced a few new cichlids and a couple of new plants. About two weeks later and I am seeing red algae on some of my plants and a few small spots on the glass and gravel. It is not alot, but I want to take care of it before it gets out of hand. I cannot find alot of info on red algae. Please help. - Michelle
Answer: Hi Michelle, here's a good feature on the red algae:
Control of Red Algae in the Freshwater Aquarium. Good luck.
~ Red Algae Hybrid ~
Question: I have had my tank set up for a while. The inhabitants and such can be found under the 46 gallon section of www.geocities.com/aqua_ajb. In my tank I find these little stringy balls of grey matter. They started to appear after I upgraded my lighting from 60W to 124W. I do not know what these little grey things are, but would like to know what cause them so I can fix it. I also would like to what they are. Sometimes they are very easy to pull from the leaves of a plant, and come in a big mass. Other times they are attached to the plant leaves and don't come of very well at all. It is my guess that these stupid things are algae, but I would like to know for sure. Thank you for your help. AJB
Answer: Hi AJB, I've heard about a hybrid of red algae that looks blackish and collects mostly on plant leaves. This may be your culprit. I see you already have a Siamese algae eater -- want to consider adding a couple more? Or maybe a couple of Otos. If the algae (ye, I tend to imagine this is algae) doesn't come off from the leaves easily, cut off and throw away the affected leaves. Then next time you clean out your filters, be sure to wash them thoroughly to eliminate algae spores. Let me know if any of the suggestions work. Good luck.
~ Algae Attack! -- A Recap ~
Question: HELP...I have a 10 gallon tank with 3 cherry barb fish. We are having a terrible time with algae growth. We will do a complete water change that includes new rocks, filters, and decorations. The tank will be troughly scrubbed. Within 5-7 weeks, algae starts growing. I have used the algae destroyer and some type of tablet to try to control the growth. No luck. The light is only on for 4 hours a day and that time is in the evening. No direct sunlight on the tank. We do feed the fish at night. We are getting ready to get rid of the tank. Any suggestions on how to keep the algae from coming back. thanks - LLP
Answer: Hi LLP, these things can be annoying, huh? Do you have plants in the tank? One trick is to add a few plants to consume the nutrients that the algae are feasting on. If the plants use up the nutrients, the algae won't have enough to live on. A more reliable solution is algae eaters -- my recommendation is the Otocinclus. They're small, peaceful, and should be happy to keep your tank algae-free. Good luck.
~ Online References -- All About Algae ~
Algae in the Aquarium
Robyn's Aquarium Algae Page
Control of Red Algae in the Freshwater Aquarium