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FAQs on Controlling Marine Green Water (Planktonic Algae)

Related FAQs: Green Algae Control 1, Green Algae Control 2, Green Algae Control 3, Green Algae Control 4, Green algae Control 5, Green Algae Control 6, Green Algae Control 7, & By Group: Bryopsis & Derbesia, Bubble Algae (Boergesenia, Dictyosphaeria, Valonia...), Caulerpa Compatibility/Control, Chaetomorpha, Halimeda, Neomeris, Hair (Filamentous, Attached) Algae, Green Water  (Planktonic) Algae Blooms, & Algae ControlMarine Algicide Use, Nutrient Limitation, Marine Algae Eaters, Culturing Macro-Algae; CaulerpasControlling: BGA/Cyano, Red/Encrusting Algae, Brown/Diatom Algae

Related Articles: Embracing Biodiversity, Green Algae By Mark E. Evans, Algae Control, Caulerpa Algae, Marine Maintenance, Nutrient Control and Export, Marine Scavengers, Snails, Hermit Crabs, Mithrax/Emerald Green Crabs, Sea Urchins, Blennies, Algae Filters, Ctenochaetus/Bristle Mouth Tangs, Zebrasoma/Sailfin Tangs, Skimmers, Skimmer Selection, Marine Algae, Coralline Algae, Green Algae, Brown Algae, Blue-Green "Algae"/(Cyanobacteria)Diatoms, Brown Algae

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New Print and eBook on Amazon

Marine Aquarium Algae Control

by Robert (Bob) Fenner

Green water in marine aquarium 04/05/2008 I have a 150 gallon marine tank that I set up in December. I cycled the tank and everything seemed perfect so I started adding inverts, fish and corals. Now I have water that looks like pea soup and I am out of ideas. I have a protein skimmer. I do weekly, ten percent water changes. I have good water circulation and run an R.O. Filter. I have checked and double checked the cartridge seating in the R.O. I have been running Phosguard and Reef Carbon for two weeks. I set up a fan to control the temp. Please Help. Any suggestion would be a blessing at this point. <<Sounds like a common algae bloom. I would suggest adding am external mechanical filter to the tank, and keep media cleaned weekly to clear the floating up. I presume your skimmer is working correctly, I.E producing thick dark brown skimmate. Read reading here and linked articles and FAQ's http://www.wetwebmedia.com/algaeconMar.htm>> <<Hope this helps. A Nixon>>

Green water! -02/08/08 Dear Folks at WetWebMedia, I hope you can help me! For the last few weeks I have been experiencing green water in my reef tank. A few clues have led me to the conclusion that this is a phytoplankton bloom. First, the problem worsens when the lights are left on, and gets better when the lights are left off. Second, upon 40X magnification, I can see very small unicellular spheres. <Ooo, you have a microscope. Cool!> My reef tank is a 90 gallon system and is about 4 months old. I have a typhoon skimmer running in the sump. The fish population includes two clowns, two firefish, 6 green chromis, and 1 canary wrasse. The corals include a fox coral, pulsing Xenia, Montipora capricornis, a blue acropora, a leather mushroom, some zooanthids, a small frogspawn, and yellow polyps (which have already created babies on the other side of the tank...very cool!). <very cool indeed!> I should note that the Xenia has previously been pulsing like mad, but in the last few days the pulsing has decreased. Please read on. <This happens. We still don't know exactly how or why.> We have cycled through the usual algae blooms associated with new tanks, and for 2 months the tank has been perfect except for low calcium and rather high alkalinity. After testing freshly prepared salt water (Instant Ocean), I found that the these issues (the low calcium and high alk) are stemming from the salt brand I was using. So, upon consultation with LFS, I switched to a "better" brand (Tropic Marin). And friends, this is when the trouble began! So all parameters are now testing great, but the water is green, green, green!! Today I could not see the back of the tank! I have performed two 5% water changes over the last month, so in theory the tank is now 10% Tropic Marin Salt, 90% IO. I tested phosphate expecting high levels, but no, the levels are low (between 0 and 0.1 ppm). <The problem with testing these things when you have an algal bloom is that the algae is most likely consuming them to the point that they don't show up in tests.> Alkalinity is 3.5 meq/L, pH is 8.2, calcium is 380 mg/L, Nitrites and Nitrates are 0, and I keep the SG at 1.025. One last note, I did overfeed the tank in an attempt to save a starving coral goby (failed attempt). The over-feeding occurred just before I switched salt brands. <This could explain the algae.> I have placed a phosphate absorbing filter in the sump stream. Other than leaving the lights off every other day, I cannot think of any other solutions. Please help! I could not find much on phytoplankton blooms on the media site. <In my experience, nothing clears up phytoplankton like diatom filtration. If you have a magnum or some other canister filter with which you can use diatom powder, I would highly suggest you do this. Seriously, a diatom filter can make your water crystal clear again in just hours. But don't leave it on for days on end. It will have to be cleaned out after a day or so.> With Sincere Thanks, Tina Henry <De nada, Sara M.>

Help with Green Water Dear WWM Crew:  <Hi John, MacL here with you tonight. Let me apologize I've been having migraine problems sorry for the delay in response.> I have a 150 gal and 30 gal wet/dry with bio balls and an AMiracle protein skimmer with a very large cup on it. I get about 1/4 cup of skimmate every week. setup with the following: 1 Moorish Idol 1 Yellow Tang 1 Hippo Tang 1 Flame Hawk 1 Pygmy Angel 1 Diamond Watchman Goby 1 Six Line Wrasse 1 Firefish Goby 1 Sailfin Algae Blenny 1 Condy Anemone Several large leather corals and a large colony of green Star Polyps Several small blue legged hermit crabs and snails SG - 1.021 pH - 7.9 Amm - 0 Nitrates- 0 Nitrites- 60 - 80 I perform a 20% water change every 2 weeks. This tank is about 8 years old, however, I have only owned it since June of 2004.  <Sounds lovely!> My question is twofold. First, I seem to have green water. The substrate looks green when looking through the top of the tank to the bottom.  <Not necessarily green water but definitely an algae bloom.>  I feed Formula 2 twice a day. I am curious if a canister filter would remove the green color from the water.  <A canister filter or any other type of mechanical filtration filled with Carbon or with a PolyFilter will take it out.>  All the livestock seems to be doing well.  <That's the most important thing.> Second, I need to know how to raise my pH and lower my nitrates. I would like to get them down around 10-20 at the most.  <Way to high obviously. My first thought is to cut way back on your feeding. The carbon will help temporarily if you do get the canister.>  Is this possible with a canister filter?  <Many people feel that the nitrates are brought about by the bioballs, especially if the tank is as old as your is. They feel that the bioballs get a rise in nitrates from a detritus build up. The solution is to remove the bioballs but that can effect the stability of your tank. Especially if that is the major filtration. You don't mention if you have live rock in the tank and powerheads for circulation but the one thing I might mention is to be sure you have lots of surface movement for oxygen exchange.> Second, I am curious about the amount of skimmate I am getting for such a large tank and skimmer. The skimmate is dark green in color, but I do not get much of it.  <You might need to clean out your protein skimmer with vinegar. Hope this helps. MacL> Thanks for your help. John Banks - Idaho, USA

Green water addendum 16 Feb 2005 I did forget to mention that I have about 160lbs of live rock. The lighting is 2 96W compact fluorescent 10000K and 2 420NM Actinic lights. The Actinic lamps stay on 14 hours a day and the 10000K lamps are on 12. Also, I have 3 Hagen 802 powerheads. Currently, the bio balls are the only filtration in the sump. Can I get away with feeding once a day or should I still feed twice, but feed less.  <I would try to cut down and if that doesn't work then go to once a day.>  Also, my hippo tang gets small white spots on its body that seem to come and go. The show up and a day or two later, they are gone. What could they be?  <On a hippo its probably ich but he's obviously handling it. You might include a cleaner shrimp for some assistance. Oh and you have live rock so you have filtration other than the bioballs. So if all else fails you might contact the crew and get some instructions on getting rid of the bioballs. Good luck, MacL>

Green water? WWM crew, <How goes it, Maddox here tonight> I'm having problems with my saltwater tank. It's totally green. <Not fun...> I have looked for hours on your most excellent site <I'm grateful for being able to follow in giants' footsteps, to borrow a phrase from Newton> for some reference to my specific problem, but I couldn't find an answer. Please help me out. My tank specs are as follows: Started 12/25/03 about 6mths. ago 55 gal. Marine, 45# of Fuji live rock, 5 Damsels, Clown, Mandarin Goby <Do make sure that this fish is able to find the food it needs - copepods, amphipods, and other small crustaceans as it doesn't readily take prepared foods>, 5 Hermits, 6 Snails, Flower Anemone, and a Bubble Anemone. Use Wet/Dry filter, and small Protein Skimmer <What type?  Is it collecting at least a cup of skimmate every few days?  Green water \ Algae doesn't appear from nowhere; it's caused by excessive dissolved organics.  You should be collecting a cup of skimmate at least every 3 days if it is functioning properly>. Lighting is PC <Watts?  Color temperate?>. I religiously change 6 gallons of water per week. <Might want to up that to 12 gallons a week until you're able to get the organics under control> I had a problem with Brown Algae in the beginning, but cured it by using distilled water from store. I recently purchased a 6 stage RO/DI unit to help curb the money vs. water problem. <So your make up water is completely free from nitrates and phosphates?> I have not lost any livestock since the tank was started <good to hear> and all chemical parameters are normal i.e.: PH 8.3, Ca=550mg/L, PO4=0, et al. <What about nitrates?> Had a large outbreak of Turtle Weed (?as best as I can tell) recently. The water started looking green, so I pulled out most of the Turtle weed by hand. <Most macro algae are beneficial> The water continued to get greener and greener. It is now to the point that I can't even see my LR. <Ouch definitely not good for your anemones> Please advise on what the actual problem is and what I should do to get clear water again. <Are you employing any chemical mediums?  If not, I would definitely recommend using a Poly Filter from Poly Bio Marine, and Seachem's Matrix carbon or SeaGel, perform more frequent water changes, and make sure your skimmer is working efficiently.  Also, test your Nitrates and make sure they're under 10ppm> Thanks, David <Good luck, and let me know how it goes - M. Maddox>  

Green water Please, please can you help me, the water in my 180l marine tank has gone green and visibility is down to about 3 inches, I have had this problem for 10 days and matters are not improving. My levels are fine but should I test for phosphate?  <Possibly... what do you consider has led to your system being so out of balance?> I do have two poly filters in my filters, added last weekend, but they do not seem to have improved matters. I have new carbon and a have a skimmer which appears to have removed the Myxazin with which I successfully treated my Tang's cloudy eye. Would the installation of a UV Sterilizer solve this and my next problem? <It would help> How do I break the cycle of reinfection with my itchy Tang? <Please read here: http://www.wetwebmedia.com/parasittksfaqs.htm and the links beyond> I dip him and then he is fine for a couple of days and then he itches again. I have live rock and a hermit crab which I need to be careful of. If I added a chemical to treat the green water what would you recommend and would I need to take any special precautions to make sure my fish and crab did not come to any harm. <No need, desire to add chemicals as algicides, clarifying agents... Please study our site: www.WetWebMedia.com re set-up and maintenance, particularly Algae and their control: http://www.wetwebmedia.com/avoidingalgaeproblesm.htm Bob Fenner> Please, please help, James Matthams

Fighting Green Water  5/31/06 I have been having this problem for a while now and I was hoping you could help out. < I will do the best I can, but I am definitely no Bob! > <<Only a need and possibility to be yourself>> I will start by listing my parameters. < Thank you, very considerate! > 75 Gallon approx 20 gal sump with skimmer overflow AquaC Urchin Skimmer with Maxijet 1200 producing about 1/2" dark skimmate in collection cup daily. < No complaints there. > Pentair 3000 (780GPH) return pump with loop output (3 output ports) Overflow return to sump (Wet/Dry) with sponge < The sponge will trap detritus, and allow it to break down into nutrients for the green water to use. If you must use a sponge to retard the retuning of micro-bubbles to the tank, try to rinse it well, at least once a week. > 2 150w Visi-therm heaters 4 32W T8 overdriven fluorescents (3 -Phillips Natural Sunshine Full spectrum 5000K, 1 Coralife actinic) < That may be too much red and yellow spectrum, especially as the tubes age, and shift to more red! > I figure this is the equivalent of about 272W Glass canopy < If the glass is not low iron polarized glass, such as Oceanic used to use, and/or if it is not kept immaculately clean, it can and will filter light, changing the desired spectrum. > Running Seachem active carbon and micro filter pad in drip tray < The carbon should be replaced frequently, to prevent it from dumping what it has absorbed. Use smaller amounts, and replace it at least weekly. > <1" aragonite substrate 50lbs of reef rock 15lbs live rock 3" yellow tang 2x1.5" green chromis 2.5" chalk basslet 1.5" ocellaris clownfish 3" convict blenny yellow polyps coral Parameters ------------------ ammonia: 0, nitrite: 0, ph: 8.2, nitrate: 0, phosphate: 0, temp: 79, spg: 1.023 The tank has been operational for about 3.5months. Tank was fully cycled with liverock before adding any organisms. I have a wet/dry and am working to remove the media. I have removed half of it currently and am waiting a few weeks to remove half of what is left. But aside from that lets get to my problem. < You are already on the right track, by removing the bio-balls. > I have unclear water. It is a green haze. It has been like this for a while now and I want to get rid of it. Items in the back of the tank are foggy when looking from the front. I figured I could starve out this green water through skimming and cutting back on feedings but things do not seem to be changing. (I feed generally frozen mysis/brine shrimp a bit at a time until they do not seem interested) I do not think the problem is overfeeding as I am not leaving any food floating around and phosphates are 0. < Your method of attack is appropriate. Do you rinse your frozen food well? The gel binders and juices contained therein are laden with phosphates. You will not be able to test these phosphates once the solution is added to the tank, for it is used up quickly by the micro-algae in question. > I want to get to clear water. I am open to any suggestions on what to do. I am thinking that maybe the problem is with the 5000K full spectrum lights. < Bingo! That spectrum is closely simulating the shallow marsh areas around coastlines. You know how snotty and slimy they can be! The spectrum we are more want to replicate is that of much deeper water, say about 30-40 feet deep. At this depth, most of the red spectrum is filtered out, with heavy amounts of blue being visible. Most undesirable algae do not fare well when red light is limited and blue light is offered. > Maybe with the 12hour photoperiod this is causing excessive free floating algae. < Yes, the extended photoperiod is encouraging the algae, while also shortening the usable lifespan of the fluorescents. Someone much smarter than me stated that corals can only use so much light. They apparently do not collect light all day long, as one would assume. Some of the photoperiod is actually blocked by the corals, who may already be saturated with as much light energy as they can process in that one day. Strange, I know, but true. I would try a eight hour photoperiod, at least until everything is under control. Then maybe step it back up, maybe not. > Should I change the 5000K bulbs to 6500K Phillips daylight deluxe? (They have a good lumens and high CRI value) < I am not familiar with those lamps in relation to coral growth, but to change the color temperature would be wise. Think about using two 6500's with two actinics. That should lower the amount of red light you are producing. Also, try to keep your tubes changed out every six to eight months, whether or not they "need" it. This should help you avoid getting caught up in a shift to red! > Please help me Bob!!! If there is anything else you need to know from me please let me know. < I know I am no Bob, but I hope I was of some assistance. Maybe he will jump in and hit upon points I most probably missed! (Hint, hint!) > Regards, Jeremy < Anytime! RichardB >

Knocking Out Nuisance Algae! Dear WWM experts, <Yikes! "Expert" is a scary title! How 'bout us "fellow hobbyist who's made plenty of mistakes in his time...?" Scott F. here today!> I have a 46 gal. marine w/ live rock and crushed coral substrate setup for 4 months.  No fish, just hermit crabs, small queen conchs, sea stars, and a feisty Coral Banded Shrimp.  I have a Visijet skimmer (I took the plunge - to be replaced by Remora skimmer next week). <Good skimmer...you'll like it!> I am in the midst of an ongoing, heavy algae bloom with water column visibility (green water) between 6 inches and 1 foot for about 3 weeks. <No fun at all...> I bought a Magnum HOT and ran the micro filter to clear the water overnight but had no luck.  Should the Magnum clear the algae bloom or should I switch it for a vortex diatom filter? <Well, any mechanical filtration that you employ will just be a "band aid"; the real important thing is to get at the source of the algae. You need to find out the cause of the algal bloom. Nuisance algae blooms almost always have their source in excesses of nutrients, coupled with available light. Run some basic water parameter tests (pH, nitrate, phosphate, alkalinity) and I'll wager that you might find something amiss. Think about how nutrients could have accumulated in the system: Are you feeding excessively? Liquid foods are particularly suspect if used heavily. What kind of source water are you using (RO/DI)? Are you conducting regular water changes (small, frequent changes work best, IMO)? Do you regularly employ chemical filtration media (i.e.; activated carbon and/or PolyFilter)? Do you keep a good water motion going at all times? Are you using lots of additives? If so, ask yourself what you are using them for? Your more capable Aqua C skimmer will help yank out excessive nutrients before they have a chance to accumulate and degrade water quality.> Thanks for your insights, Matt <My pleasure, Matt. I hope these ideas give you a starting point in your investigation as to the cause of your algal bloom...The truth is out there! Good luck! Regards, Scott F.>

Green reef (algae problem) Hi! I have a 45 gallon reef tank with some seriously green water.  Green enough that I can honestly say that I miss being able to see my fish. I've got a couple of damsels, a small hippo tang, a tomato clown, and a rose anemone, and a few other miscellaneous inverts and macroalgae.  I use and Eheim Ecco canister filter, CPR BakPak skimmer, an Ebo, a couple of powerheads for water flow, 196 watts in powercompacts, and about 50 pounds of liverock.  My system is about 9 months old, but saw a major revamping about 3 months ago.  My water conditions are perfect, aside from about 10ppm of nitrates.  The green started two weekends ago when I was out of town for a few days, and has become progressively worse ever since.   I did add iodine, strontium, essential elements (all Kent), and calcium (Salifert) with a water change before I left (about the time things started to head downhill)...big mistake?   I did a 15% water change a week ago, and another 25% change yesterday, but the green just comes back with a vengeance.  My LFS assured me that it was because of the heat spell, which made sense to me, because we DID have a heat spell last week which brought my water up to around 82, but I've since brought it down to 78 and the problem continues.  I clean the skimmer daily, I've got all my fish fasting, and I've been using RO/DI water with Tropic Marin sea salts for the changes. Aside from water changes...what can I do?  UV sterilizing?  Will my system be fine if I just sit it out and wait for nature to run it's course through my tank?  Thanks for your help! Scott << Scott, it just may be your lucky day.  A club member of mine had this exact problem about two months ago.  People suggested everything, and he tried everything.  Then one day he added a UV sterilizer.  None of us thought it would work, but it cleared it up in one day!  It was unbelievable.  Please borrow or purchase one, and let me know if that works.  I would be very interested to know if that was the real solution, or a coincidence. >> <<  Adam Blundell  >>

Clearing The Green Cloud (Algae Problem) Hi - I was reading through your FAQ on diatom filters and info on algae, and it seems you have the expertise to know the best way to solve my aquatic issue. <Well, maybe not "expertise"- but lots of experience! Scott F. with you today!> I have a 75 gallon tank that started out great, and developed serious algae problems - characterized by water so cloudy and green that it was difficult to even see the fish. The only way I was able to temporarily solve this problem was via large - at least 50% - water changes. The tank has MORE than adequate filtration with a Fluval 400 canister filter and 2 forward powerheads and 2 reverse powerheads connected to an undergravel filter. I now have no fish in the tank, and the water is clearer than before, but some cloudiness remains. I am afraid that as soon as I reintroduce fish, the water will go to hell again. Interestingly, the physical tank itself is almost spotless -no algae on the glass, etc. <Unusual, but not unheard of!> Anyway, I think the following is true, please correct me if I am wrong. The algae is "green algae", possibly Volvox, and will not be filtered by a canister filter - it probably is a result of too much light, I live in a "light and bright" town home and installed a 99% UV blocking window blind to attempt to solve the problem -- this helped, but did not fix it. <Well, light and excess nutrients conspire to cause these algae blooms. Light in and of itself is not so much of a problem. What you need to do is to work on lowering the nutrient load in the tank. Utilize aggressive chemical filtration, with carbon and/or Poly Filter to help scavenge nutrients, and use high-quality source water.> A diatom filter or a UV filter/sterilizer might be needed to solve the problem. <A good combination with free-floating algae> I've been reading about diatom filters and that would seem to address the cloudy water issue. I've also seen UV filters mentioned, although I don't know what this is exactly. If this is a different type of lighting - a special tube with a certain wavelength range or something - that would be worth trying. <Well, you essentially described a UV sterilizer. Water passes through at a rate which is conducive to "zapping" undesired organisms...> No live plants or rock in my tank, and it uses 2 48" fluorescent tubes. Also, I'm "cloaking" the entire tank with a large comforter for a 72 hour period to see if that helps. I want the crystal clear water I've seen in other tanks, including my other aquariums. <A worthwhile goal. I think that a diatom filter, in combination with the aforementioned chemical filtration and good husbandry techniques on your part will do the trick!> So what is the best course of action? Should I run out and buy a diatom filter? Other comments? Thanks! Jason <Well, Jason, I hate to recommend another expensive piece of gear, but the diatom filter sounds like a good idea here. Also, invest in some test kits and see what's going on in the water...Should give you some good insights! Good luck! Regards, Scott F> ps - LOVE the website!! wish my LFS had this kind of expertise...

Green Water I had e-mailed you a few weeks ago and in a panic of losing my fish and didn't give you details of my tank and my dilemma. I lost my bicolor angel and have sent my other two fish to a friend's tank until I can fix my water problem. My tank is a 47 gallon, fish only tank with a wet/dry system that uses bio balls and a sump under my main tank. The system has worked properly for about 4 months (meaning I had no water problems and nitrate, nitrite, ammonia, and ph levels were all adequate). About one month ago my water turned green. I checked the four tests that I mentioned previously and all were in the appropriate ranges. I waited for about two weeks to see if it would clear up on its own. That is when I lost the angel and sent my other fish on their little, hopefully short, vacation. I have since done a complete water change because the water was so bad (murky and green). When I refilled the tank I used approximately half "new" water and half cycled water from my friend's tank. The tank was running for about two weeks with no notable problems. All of the water tests were again in the appropriate ranges. I came home from work tonight and I stood in front of a green water tank again. There are no fish in the tank now but, again, seemingly overnight my water is murky and green. I really am puzzled and could use any advice. I have been a freshwater aquarist for about 17 years and have had a salt tank for about eight years and I have never faced this sort of problem before. It's not easy being green. Thanks for your help. Brady < Wow... somewhere, some ready source of nutrient has gotten, is getting into your system... and there isn't enough of anything else to compete with it...  A few approaches could be tried... chemical filtration, maybe a Polyfilter to remove some/most of the nutrient, and a diatom filter (brand name or no) to remove the single celled algae and the nutrients bound up in them... Shading the tank... Encouraging a collapse by over-stimulating the mix of algae... but none of these techniques appeal to me: too messy, and unstable... Instead, I would place as much live rock as you like/can afford and consider any/all of the "other" possibilities... but the Live Rock will re-set the system... and exclude much chance of a recurrence of your "free living" algae bloom problems... Get/use live rock for your system... even though it is "Fish Only". Bob Fenner> 

Green Water Hello there, Small problem I have checked your site and I have not really found an answer that can help me. I have green water in my saltwater tank. It will not go away. Even though I want it to it will not. How do I get rid of it? I tested everything and it is all good. Why am I getting this green water? I used to have such a pretty tank now I have a farmers pond in my living room. HELP! Kenny <Hi Kenny, There is a lot of info on conditions causing green water. Simply type "green water" in the Google search engine and follow the resulting links. You can start with : www.wetwebmedia.com/greenalg.htm www.wetwebmedia.com/avoidingalgaeproblesm.htm    www.wetwebmedia.com/algaeconMar.htm  Almost all of these water conditions are due to excess nutrient/insufficient export/water changes/overfeeding or elements present in the source water.  Craig>

New Print and eBook on Amazon

Marine Aquarium Algae Control

by Robert (Bob) Fenner

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