Please visit our Sponsors
FAQs on Freshwater Algicides

Related Articles: Algae Control in Freshwater Aquariums by Bob Fenner, Dealing With Algae in Freshwater Aquaria by Neale Monks, (some) Algae (in moderation) Can Be Your Friend, ppt presentation, Part 1, Part 2, Part 3, Part 4, Part 5, Part 6, by Bob Fenner, Algae Eaters, OtocinclusLoricariidsSiamese Algae Eaters/Crossocheilus

Related FAQs: Freshwater Algae 1, Algae Eaters, Aquarium MaintenanceFreshwater Aquarium Water Quality, Treating Tap Water for Aquarium Use, pH, Alkalinity, Acidity, Freshwater Algae Control, Algae Control, Foods, Feeding, Aquatic Nutrition, Disease

They are toxic to all life... directly and indirectly... from the by-products of decomposition... And entirely avoidable... Consider the causes... sources of pest algal growth, and solve these.

Corydoras shedding slime coats   8/16/11
Hello, about 2 weeks ago my Girlfriend tried to "help" my community tank by pouring about 10X the dosage of Algaefix which is designed to reduce algae,
<Argh! These products are dangerous, even at the right dose, and should NEVER be used, in my opinion. Even if you magically kill all the algae in a tank, if conditions favour algae, it'll be back in weeks. So the art to removing algae is to change the conditions in the aquarium. Typically this involves adding lots of fast-growing plants under suitably bright light, and then installing a few suitable algae-eating animals (Nerite snails are ideal) that will consume any algae that remains.>
however she managed to kill most of my fish and seriously compromising the health of the others. When I discovered the poisoning most of my fish that were still alive were floating at the top, and my Corys were on their sides. I quickly transferred them all to my goldfish tank, and completely drained my community tank and fixed the problem etc etc. The surviving fish are two long fin black skirted tetras, one diamond tetra and two large leopard Corys. The tetras seem to have returned to normal health.
<Sounds a lucky escape for them!>
However, The Corys went through a few days of touch and go, not eating just sitting there etc. One would swim near the top always gulping air, probably because its lungs were seriously damaged.
<Hmm'¦ no, I'd guess the reverse. If excess slime or chemical irritation was affecting its gills, it'll gulp air and absorb oxygen through its gut. That's what these catfish do. It's normal, and once conditions improve, the Corydoras will gulp air less frequently.>
Now a few weeks later they are doing much better, still not as active before the accident, but are eating and moving around more. However they are still lethargic and also I noticed that their slime coats are starting to fall off.
<Are you sure it's mucous and not skin?>
The water conditions are perfect for them and I recently restocked my Corydoras population, 5 leopard Corys and 1 sterbai Cory and they are all in perfect health in perfect water. The water is at a constant 70-72 degrees, about 30 ppm of General Hardness, and 6-7 PH, no nitrates no nitrites and no ammonia. Will the Corys regain previous health over time,
<If they can, yes.>
or do I have to treat them in some way,
or are they on a slow downward spiral to death?
<Likely not.>
Any help or advice or even information will be greatly appreciated.
Thanks for your time, Jesse
<My gut feeling is your fish will be okay, given time. Cheers, Neale.>

Algae attack... chemicals...   3/26/08 Hi WetWebMedia, I have an algae problem in my tank and was thinking about using some chemicals to stop the growth. <Don't. Think for one second about the effect a bunch of dead stuff is going to have on your water quality. Then think about just how long it will take for the algae to come back. Total waste of time and money.> My question is this, will it harm my Plecos since they eat the algae? <Indirectly, yes, a bunch of dead stuff can harm any and all fish in the aquarium.> Or will it be safe? <Not really.> I still feed them algae wafers. Thanks for your help. <Algae is ONLY, repeat ONLY, beaten using fast-growing plants under bright lights. Everything else is a waste of time: anti-algae potions, Plecs, shrimps, snails, etc. Either remove algae manually or simply accept it as part of the natural look of the aquarium. Cheers, Neale.>

ADF and algae... algicides...  2/27/08 Dear Crew, I have an 8.8 gal book shelf tank containing four African Dwarf Frogs and two Otocinclus. Water temperature is set to 76 degrees. The tank is far from direct sunlight and I use the hood light from about 7 a.m. to 9 p.m. I am having a constant problem with both brown algae and green, floating algae. I added in the Otos to see if they could help keep the brown algae down, but while they help some, they are not staying on top of things and they seem to have no affect on the green. At least they do get along with my froggies but to keep enough to handle all the brown algae I might have to have so many Otos that they would be a real bother to the frogs. About a month ago I did a routine of erythromycin for five days and it cleared the green stuff very well, but ... it has come back and I don't think putting anti-biotics in the tank on a regular basis is a very good idea. Jungle has an algae treatment called "No More Algae." The active ingredients are Diuron and a small bit of copper sulfate. The package states to not use on invertebrates as do many aquarium chemicals. I wrote the company, asking if it was safe to use with ADF's and they have not replied. Thus I am turning to you. "Is it Ok to use "No More Algae" in my African Dwarf Frog tank? Thanks so much for any guidance you can give me. Mike <Mike, even if the "No More Algae" product was non-toxic, you shouldn't use it anyway. When algae dies, it rots. When it rots, it produces ammonia. In any tank that is bad news; in an 8 gallon tank it's a disaster! Next up, even if you kill the algae now, it'll be just as bad in a month. Algae gets into the tank from the air or in water changes. So you can't "sterilise" the system in any meaningful way. Algae is caused by a complex of things, the most critical of which is this: lack of fast-growing plants. Tanks with lots of healthy, fast-growing plants under bright light don't have algae problems. Simple as that. So there's your solution. Ensure the lighting above the tank is at least 1.5, and ideally 2, watts per gallon, add some fast-growing plants (Cabomba, Hygrophila, Vallisneria, etc) and then sit back. The plants will eliminate the algae via allelopathy. No other solution works. None. Nix. Nada. If you don't want to go that route, I'm afraid all that's left is manually removing the algae with a wipe or scraper. Incidentally, adding fish or snails has zero effect, because all the extra livestock does is dump more ammonia and CO2 in the water, making the algae even more happy! Cheers, Neale.>

Re: ADF and algae 2/27/08 Hi Neale, Well, that settles that. I'll be in town tomorrow and I'll see if my LFS has any of these. I suspect they do. Seems like a much better solution than doing any chemical thing. Thanks so much. I'll let you know how it works out for me. Mike <Hi Mike. Fast-growing plants aren't difficult to obtain. Even floating plants can work well. But the effect they have is dramatic once they're growing. Does depend somewhat on the lighting though -- the plants have to be growing well to stop the algae. If you want to do some reading, look up "allelopathy" in aquaria; quite how, why plants stop algae isn't known, but they do. Cheers, Neale.>

Tiger Barb, hlth./env., algicide use    2-4-08 I have had a 29 gallon tank for four months now (before that I had a 10 gallon tank for one year), and when I first got it I moved my one remaining tiger barb to my tank. <Hello, Merritt here. That must be one lonely tiger barb, these fish are schooling and need to be in groups of six or more for them to be happy.> I had purchased him August 29, he seem very happy in the tank swimming all around and eating plenty. Well my parents did not like having just one little fish in there so I bought six other fish from Wal-mart and kept them in their own tank for three weeks. <What species of fish did you buy? And did you monitor the water chemistry? (pH, ammonia, nitrate, nitrites?)> One of them was really small but my parents did not want me to have two tanks so he went in with the others. <So your fish are in the 10 gallon or 29 gallon?> Everything went fine, until the algae started, so I bought two of the smallest algae eaters that I could find (I do not like algae eaters they look ugly). <I personally don't like them either> They where so small they could not keep up with the growth so I put in "Jungle-No more algae" then within two days they where each dead, can I not put in algae tablets with algae eaters? <You might have suffered a change in water chemistry when adding the other fish which could have caused your fish demise. Many algae destroying products are known to be harmful to specific species of fish and this could have been the reason your fish died. I usually don't recommend algicides of any sort. Also, your problem with algae is due to a high amount of nutrients in the water, are you feeding your fish too much? Or not enough water changes? Here are some links to algae problems and freshwater care, http://www.wetwebmedia.com/FWSubWebIndex/fwalgcontrol.htm and http://www.wetwebmedia.com/FWSubWebIndex/fwh2ochgs.htm. Take a look at these areas of WWM and others, as the answers to your questions are all on our website. Hope this helps! Merritt>

Depressed Bettas. Actually FW fish poisoned with algicide    12/9/07 Hi crew. I hope you can help me. Last weekend I treated my 1 gal Betta tank and my 2.5 tank (some Corys and tetras reside with Betta) with Tetra Algae Control. <Mmmm... not a very safe product> Unfortunately I did my math wrong (directions for 12 gal tank) and I over dosed. Once I realized, I quickly did a 50% water change but had to use tap water treated with Aqua Safe. I lost the Corys and a tetra and no both Bettas are very depressed and don't seem to be eating. they used to come up to med at feeding time, now they are listless. I changed more water today, what else should I do? Thanks, Tamra <Monitor nitrogenous waste accumulation (esp. Ammonia, Nitrite), read on WWM re controlling these if they're measurable, cut way back on feeding, use some activated carbon in your filter flow path, and hope, be patient. Bob Fenner>

Gold fantail thyroid tumor? Likely Simazine poisoned  - 1/22/07 Hello crew, <Rachel> I have a one-eyed gold fantail named Polyphemos, <Ahh!> about 5 inches long from nose to the end of his tail.  A few months ago I bought a 5 gallon Regent acrylic tank for him (up from his old 2.5 gallon) <Yikes... needs even much more room than this> with a built-in filtration system and bio-wheel.  After reading the FAQs, I realize he should have twice that much space, <Easily... better four or more times> but I have nowhere to put a 10 gal. tank until I move out of this apartment.  Having lost several goldfish in years past due to poor water quality, I've been diligent about changing Pol's water - 20-30% weekly. <Good> I had a friend feed Pol over Christmas break.  He seemed fine when I got back, although there was a lot of algae build-up, and his dorsal fin and tail had changed to black - I chalked this up to the dark algae-covered environment. <Mmm, both more likely due to declining water quality> I scraped some of the algae off the tank, did a partial water change, changed the filter, and added the recommended amount of "Algae Destroyer Liquid." <... Simazine... toxic... I do NOT endorse the use of this compound for/in ornamental aquatic use>   Pol seemed fine for the rest of that week, and soon began to change back to his normal gold color.  However, he has now lost his appetite completely, and as far as I know has not eaten any of his food for close to a week. (Until yesterday his tank was bare except for some river stones, which made keeping track of and disposing uneaten food a breeze.)  He now spends most of his time sitting in the corner of the tank with his nose in the air and is breathing heavily. <Start... changing the water... daily... a gallon or two... stored from days previous...>   He occasionally darts to the surface and swims normally when disturbed but soon settles back in the corner.  He doesn't seem to be in danger of starving just yet; he was perhaps overfed while I was on vacation, and his fins and scales are all normal and healthy. But when he first lost his appetite, I noticed a small reddish-white bump on his throat (see picture, attached).  I thought at first from his symptoms that it might be flukes, did a partial water change, and treated with Parasite Clear, which involved a 20-30% water change before the second dose.  48 hours after the second dose of the medicine, the bump was still there, and the area of redness appeared to have grown to 2-3 mm in size.  I did another 20-30% water change, tap water as usual properly treated with a dechlorinator, hoping that it was a water quality problem, perhaps tied to the algae remover chemicals.  Nothing seems to have helped.  Ammonia levels are undetectable, pH is at 7.5.  I don't have a nitrite/nitrate test kit, but I'm assuming from these recent water changes every couple of days that it's as close as I can get it to optimal. Usually he eats Tetra Exotic sinking mini sticks for dinner alternated with Tubifex worms for breakfast, and has always until now been extremely interested in food.  He doesn't show interest in it at all now, even when I drop the pellets directly on top of him.  Since reading the info on these pages, I've tried feeding him a thawed frozen pea, without the skin; no response.  I added a layer of gravel and some live plant bulbs last night, hoping that they could help create a more natural environment eventually, or at least a more comfortable surface for him to sit on.  Although it's been fine until now, I've also added a bubble stone in case there's a problem with oxygenation.  Besides this bump, the rapid breathing, and constant sitting in the corner, he looks healthy, but refuses to eat. From looking at the charts at www.fishyfarmacy.com, I thought it might be a thyroid tumor, Chilodonella, or maybe even a rock stuck in his throat.   <Mmm, no... these are distant possibilities... Your fish has been poisoned... by the initial questionable water quality... next, the Simazine...> I've thought about trying salt, but the last time I salted a tank my fish died - I was using table salt without iodine as recommended by some other website, and wasn't sure whether that death was due to using the wrong type of salt or the inevitable progress of the infection. <More likely by far the latter> I've got a bag full of meds from my disease-ridden poor-water quality days, but I didn't want to dose him up with more chemicals before I knew for sure what was wrong.  Any advice or diagnosis you have would be very much appreciated!  I think he could hold out for a few more days to a week without eating, but I'm out of ideas for what else to do to help him. Thank you, ~Rachel <>< <If you had another up and going system I'd move the goldfish to it... as you don't seem to... dilute the present ones toxicity... Bob Fenner> Carbon Removal, algicide use...   7/28/06 I put an algae inhibitor tablet in my tank and it said to remove the active carbon when using tablet. How long am I supposed to remove the carbon filter for?? I don't want to screw up the process. <A week or so... algicides can be real trouble... Please read here: http://www.wetwebmedia.com/maralgcidefaqs.htm Applies to freshwater as well as marine... though there are inputs for the other, carbon... posted on WWM. I'd be reading there, testing your water daily, being ready to change out water... Do read re other means of algae control. Chemical means are the least favorable. Bob Fenner>

Green Tank  7/10/06 Dear Crew, <<Greetings, Isabel. Tom>> I have a 20-gallon tank with only three fish in it.  I have had this tank with the Whisper filter for a long time.  Everything was going smoothly until we moved.  We lived in a village and had village water.  We now have moved to a lake and have a well.  The first thing we did was have the water tested and installed a water softener.  My husband and I cleaned the entire tank because it was getting cloudy and green.  We thought it was probably due to the move and length of time since we had cleaned it after the move. <<Might have been due to the move but seems unlikely that you would develop a serious algae problem without extenuating circumstances.>> Two weeks later the water is so green that you cannot see through it. <<Hardly makes for an "attractive" aquarium, does it?>> I bought a new filter thinking mine was too old.  I now have the new and the old filters running (they are not getting dirty) and I put in a gadget that "blows" the water around for circulation.   <<I'm glad you didn't simply go with a new filter and discard the "old" one. At any rate, filtration isn't the problem.>> When I changed the water, I used the start right drops and the drops of chlorine as I have done in the past. <<Jungle (TM) purports that 'Start Right' dechlorinates water so, if true, adding chlorine (not a good idea) would likely be ineffective. Your algae "burst" is due to the nutrients in your well water. These become most prominent in the summer months when the water warms in the lake and the "goodies" at the bottom of the lake rise and make their way into your water table and, hence, your well. The water softener, as you've already deduced, don't eliminate these. In a nutshell, algae will proliferate where there is a supply of nitrogen (such as "run-off" from lawn fertilizers - my folks lived on a lake in Michigan), phosphorus, potassium and, of course, light. I'd bet good money your well water has all of these...except the light.>> I need help.  I do not know what is wrong. <<Technically speaking, Isabel, nothing is "wrong". It just isn't "right" for aquaria purposes. I don't vouch for the efficacy of the product but "Algone" reportedly clears up aquariums with the problem you now have. Should you choose to use it, we'd like to hear back from you as we like to share this information with our readers. Good, bad or indifferent. We support products that "work" and will gladly advise against those that are simply a waste of money.>> Isabel <<Hope I've been of some help. Tom>>

Algone, chem. algicide opinion  4/1/06 Hello again, have you heard anything positive or negative about this product? I have read what is out there and have only seen 1 bad review. It is like everything is sponsored by the company itself. <Mmm, well, to their credit they do have a nice website: http://www.algone.com/ But this is Simazine (Princeps powder)... is too non-specific, destructive to other photosynthetic life (as in surrounding terrestrial in ponds, fountains... aquarium plants)... to get a "pro" argument from me. If you'll take the time to peruse WWM re all ornamental aquatic systems, you'll see admonitions in general re the use of algicides (a no-no governmental nominization), and encouragement to pursue other means... of prevention, competition, predation. Bob Fenner> Jay W. Thom

Hey Crew (Diatom or Cyanobacteria problem) Hey Crew <Yo!> I have a buddy who has a real problem, and a real fish problem. <Fishaholics Anonymous... trade one crutch for another I say!> I told him to email you guys, because you haven't steered me wrong with my marine setup, but he asked me to do it, and please direct me to any links if you have already answered this question. <Will definitely do> Here are the specs  55 Gallon Long Crushed Coral Substrate 2 Emperor 400s Water Quality Superb Ammonia: 0 Nitrites: 0 Nitrates: 0 11 African Cichlids Large Pieces of Slate and Granite for the aquascaping Weekly 30% water changes Here's the problem: My buddy continually fights with a red substance that sticks to everything. When you put your finger on it and wipe away it just disappears like dust, but returns in a few hours. First of all what is this substance (We have been reading and we think its Cyanobacteria.)? <I think you're likely correct> Our LFS told my friend to treat the substance with EM tablets for a few days, and then do a water change. Is this a recommended strategy for this type of problem? <Negative... Erythromycin will not "cure" the root cause/s here. Don't stoop to antibiotic use...> Do you have any other suggestions to take care of this substance? <Please read here: http://www.wetwebmedia.com/FWSubWebIndex/fwalgcontrol.htm and the linked files above> Could it be the granite or slate?  <Not likely... not a source of nutrient... and the hardness and alkalinity they're adding is of benefit> Could it be the water source? <Always a factor> The reason this perplexes us is that he has another 10 gallon tank that has a very large cichlid in it and the substance came and went away, and has not reared its ugly head since the inception of the tank. <This does happen... perhaps a better "microbial mix"> Please advise when you get a chance  Thank you, and always in awe of your genius, Eric Ross

Become a Sponsor Features:
Daily FAQs FW Daily FAQs SW Pix of the Day FW Pix of the Day New On WWM
Helpful Links Hobbyist Forum Calendars Admin Index Cover Images
Featured Sponsors: