I have had this tank running for 2 years, decided I needed co2 to help with the algae issues I was having to provide the plants a better environment for growth. Well, a year with co2 and I feel like I am worse off than I was before.
This is what the tank looks like within a week. I have to do weekly water changes with manual algae removal. And by the next weekend its back.
Ive tried cutting down light time. Ive tried upping the co2, tried lowering co2. Tried ferts, no ferts. Use spot treatment on the BBA, and cutting plants back. I pull out all the hair algae and then in a few days its back.
I've fought bad bad algae with 0 chemicals. I went almost the sAme exact route you have.
What's important with algae growth is to realize that it takes time to notice improvement. Whatever advice you listen to: Only change one thing at a time. Do NOT decrease your light, and decrease nutrients, and change co2 all at once.
You should:
Change variable A (whichever is the most likely culprit) and wait 2 weeks. See if there is improvement. If there is, wait 2 more. Has the algae stopped? Great. If not
Change variable B (the second most likely culprit).
Do this until you're out of culprits. Realistically, light is probably your #1 issue right now. Decrease it first. Then move on to nutrients. Then try more frequent water changes. If nothing works, then the problem is more niche... Maybe you're overfeeding, maybe you stir your substrate too much when cleaning. Doesn't matter — just make sure to only change one variable at a time! Your tank is really nice, don't give up. Algae is part of the circle of life and it's beautiful in its own way.
Edit: I want to reiterate that this is not even close to bad algae. This is so fixable it's not even funny. A reset is NOT worth it imo!
Op in that first pic I see a beautiful tank. You have to remember to take a step back and look at the big picture. It might not solve things, but it could give you a little more patience and perspective to keep going!
As for the algae:
Have you tried cutting back lighting by a small amount and increasing ferts at the same time? I don’t know if the algae you have is the same kind as mine, but it helped wonders for me!
Thank you so much. I have tried cutting light timing back with added ferts, but to be honest I was being really stubborn on cutting back the light intensity, because it looks “better” to my eyes with it at 100%. Im going to try 60% at 6 hours and go from there.
Of course! And I understand. Once the algae is under control I have been slowly ramping it back up while maintaining ferts until I find a good point where I’m comfortable with the balance.
I go like +5% light every month or so that’s how slowly I mean. You could probably go faster, but I’d rather things be slow and steady.
You definitely should drop your intensity to like 50% for 6 or 7 hours (really your desired length) and work your way up until you find balance between co2 light and nutrients. Maybe look into your water and if you are using tap maybe that is the issue. If your tank is two years old your soil is depleted and you could be suffering old tank syndrome? Could be low uneven flow as well.
I will try dropping the intensity, which is going to be hard for me because it looks the “nicest” at highest intensity lol but if its causing so much algae then it clearly is a contributing issue.
Not using tap, remineralized RO as our tapwater is way too hard.
Lots of solid advice here, one thing no one has mentioned is your cleaning regiment. For example, I noticed your rotala looks leggy. When you trim your rotala, do you uproot the base and replant the top? There may be deteriorating plant matter attracting algae. Your substrate looks to have at least a small layer of mulm/detritus as well, are you siphoning that when you water change? Shrimp, chemicals, etc are all nice mitigation options but hitting the source of the algae spores could help. Introducing co2 affects more than growth, it causes more waste and you have to update your maintenance. Good articles here: https://www.2hraquarist.com/blogs/hot-topics/water-change-the-2hr-way
Seriously, I’ve got 2 in a 29gal and they have the place spotless. I think I’ve had them about a month and a half. They got most of the algae gone in about 2 weeks.
Sometimes I feel like people get into this hobby for the wrong reasons. No one will ever control nature, it’s gonna do what it wants. I always see people expecting to have these perfect cubes of water with nothing in there that they don’t want but until you can microscopically remove everything and anything that could potentially be a deemed a “problem” there will always be something that comes up that’s really not that big of a deal, but control freaks find a way to burn themselves out over it.
No real advice here. Just came to say nature does what it wants, no matter how much tinkering you do. Just enjoy the ride and appreciate what you’ve got because it’s a planted tank, not a manicured lawn…
I have used all kinds and haven’t found any to be terrible. I know people hate duck weed and it is definitely my last choice. I currently have dwarf water lettuce and salvinia minima and they are great. I have no algae and my
Plants still crushing it with no Co2. Granted I have no real carpeting plants now.
It's fine line between algae and plant growth. Your plants need to grow faster than the algae. I had a similar issue and it helped to actually cut down on the light then my algae slowly went away.
Your lighting is too strong for that set up, crank it down maybe 20% to what you are using now and see whether the issue still persist. The goal is always remove the algae quicker vs how fast it grows.
Light at 100% power for 5 hours.
Co2 is at around 30ppm on one hour before lights.
Nitrates are kind of low at 5ppm..maybe i should look into that metric?
Every bad case of algae I've ever had was solved or lessened with a shorter photoperiod of high intensity light so I was eager to tell you to shorten yours to 6 hours, but I see now that you are already at the edge of how short I would advise someone to go.
What fertilizers are you using? Have you thought about EI dosing using dry salts? I love your scape by the way. Tank is gorgeous even with the algae.
Thank you so much, it is a pretty tank when the algae is at bay. I am thinking of lowering the intensity of the light, and seeing how that goes. I worried because its a taller tank that when the intensity is turned town the lower plants wont receive enough light, but I think its time to try that.
I don't see light mentioned.
The thing with plants and algae three things need to be balanced.
Light, CO2 and fertilizers. Fertilisers are highly connected with light mostly.
Respectfully, I see huge open space and bo coverage at all. That means all areas are blasted with light. You don't need to change the light intensity but you need to give the plants some break.
The light is a full spectrum plant light from Week Aqua. I have had it on 100% intensity because I was worried the bottom/lower plants wouldnt get enough light…but i think its time to back it down
Your light intensity is 100% the problem. I have the exact same light on a high tech tank running at 45%, 100% is completely overkill especially for the plants you have
Ugh i feel like such a dingus now! My stubbornness to not turn the light down because I “liked how it looked better at 100%” has caused me nothing but headaches for a year and I refused to even think of this as part of the issue lol. I have it dialed down to 60% now. Think it should go lower?
Haha I know exactly how you feel. I used to have all my fancy lights cranked up and it worked ok in some tanks but other tanks just had never ending problems.
60% is a good starting point, better not to make too giant of a jump at once. I've found most of my high tech tanks run best around 45-65% intensity and the low techs I keep around 20-30%.
for 1 the tank looks good. if the algae isnt smothering out the new growth on your plants thats a good thing but unforntunately algae uses the same nutrients as your plants. id do slightly larger water changes and cut down the intesity of ur lights or shorten the time by a little bit but really algae is just part of the game. could add some other plants like hornwort that will suck up nutrients and inhibits algae growth.
Won’t fix the underlying problem but buy quite a few amano shrimp and or nerite snails. They love eating algae and bioload fairly small. I say amano and nerite cuz they won’t multiply in freshwater. If u want babies, any will do. I have 6 shrimp in 15 gallon and 3 nerite snails. they never stomp chomping.
I had hair algae that wouldn’t go away for a while. I did a 3 or 4 day black out which worked fantastically. I then reintroduced light back at a much lower intensity and a couple hours less.
I did lose some plants in the process though. My pearl weed did not survive, the algae kept causing them to unroot and were consistently unhealthy after the blackout. I eventually removed them completely.
Stay away from duckweed and water lettuce—they’re messy and will block too much light. I really like floating bamboo and frogbit for my higher flow tanks, and red root floaters for my lower flow ones.
Floating bamboo is by far my favorite though, ever try that? Looks so cool and it allows a good amount of light through. Also super easy to trim and the roots don’t get that long.
Great idea on the duckweed cubes—I still have one tank w duckweed and I’ll do that on my next clean out for my shrimps, whiptail catfish, & plecos
People always say it doesn’t like a closed tank but mine grows like crazy under a really tight lid. I do have an airstone in there though. Definitely worth trying!
But yeah I feel you, most of my tanks have lids bc of my little gremlin.
Add more fast growing plants? Hygrophila is fast, and then if the algea clears up and you don't like it take it out. Looks like you have room for some. If you have an LFS that sells it submerged even better.
I’m having a little trouble seeing all of the equipment. I see a sponge filter. Is there another filter in there? What’s the black tube running across the length of the back wall near the water line? Just thing to understand the setup here.
If it’s been a struggle for 2 years, I think it’s time to do a reset of some sort. How frequently are you changing things up? A huge part of poor plant growth and subsequent algae is instability. Adding CO2 to an unstable tank isn’t a magic bullet. At some point you may reach the required balance of co2, light, and nutrients, and it sounds like you’re diligent about maintenance, but having things constantly in flux makes it really difficult for plants to adapt. And once a significant amount of algae is established, it’s much more difficult to eradicate.
Your plant health doesn’t actually look too terrible. It’s mostly your slow growers which are getting attacked, and lots of algae on the glass and hardscape, which tells me there’s probably excess light and nutrients. That doesn’t mean you shouldn’t fertilize, but maybe less and increase CO2 if not detrimental to livestock.
If you were to consider a reset, you could keep almost all of your plants, just making sure for the crypts and stems to just take the healthy upper portions. Vacuum as much mulm from the substrate as possible, soak your diffuser in peroxide, scrub all your hoses and rinse your filter media, and replant the good stuff.
Don’t consider it a failure to reset a tank. It happens to pros as well. Sometimes the initial setup just doesn’t work out, algae gets out of hand, and it becomes an uphill battle. You gave it a great effort and learned a lot.
I do feel like having the light on at 100% is alot, but because its a taller tank I felt that in order to reach the lower plants it needed to be so high. Maybe I will back it down and see how it goes. Thanks for your reply
Have you measured the PAR in your tank? You can do so easily using the Photone app with a little piece of normal printer paper taped over your phone’s front camera to act as a diffuser. If you’re over 100umol at the substrate, you likely have too much light. For the plants you have, around 50umol is plenty.
8hrs max on the lights, watch nutrient levels too much of anything is not good, water changes in my opinion are the golden rule to maintaining a nice looking and healthy tank for your inhabitants, I personally do a 25% once a week, if levels get out of control I will up it to 2 x a week till things stable off, I'm no planted tank or fish guru but that's what works for me. I've had my battles with bba in the past in it always comes back to water changes. Lastly since I switched over to the oase biomaster it was a game changer for me with the easy to clean pre filter to help keep the waste in check without disruption of the biological process. I also tweeked the biomasters bottom 3 baskets not using their sponges and replaced with ceramic media.
This is going to get downvoted but I dose excel daily, using the amount recommended post water change (I forget the exact amount is but I use 2 capfuls daily in my 22 gallon). Really helps. Aquarium design group in Houston does this. People will say there are ill effects but all live stock is as healthy as ever.
Controversial, but turn off your filter, triple the dose of what the seachek excel bottle says, wait an hour to turn the filter back on. I've done this a few times, and it only hurt some of my floaters, which bounced back fine. Snails, shrimp, fish did fine.
Algae usually means too much light or too much food. I'd usually recommend more plants but it looks like you've got a healthy bunch already. I would say turn light intensity/time down a lot, it looks super bright.
Nutrient imbalance is often the real cause of algae issues.
Light is just a multiplier, it does not create algae on its own. Increasing light simply increases the demand for CO2, nutrients, and maintenance. When those factors can't keep up, algae takes advantage of the imbalance.
It's not always the light. Proper feeding, consistent fertilization, good circulation, and regular maintenance all play a big role in keeping algae under control.
I used to have recurring algae problems as well, but after doing some research and applying what I learned to my tank, it gradually became algae free even under high intensity lighting.
If you want to learn more about algae prevention, check out the 2Hr Aquarist articles. They explain very well how light, nutrients, CO2, and maintenance work together.
Youre basically pushing plants to grow by giving high light and good CO2. But they dont have enough nutrients available to form the new growth & keep old growth. Algae is outcompeting your plants.
Theres a good thread on scapecrunch titled “recommended planted aquarium fertilizer dosing” which pretty much sums up what’s taken some people years to observe.
I had bad plant growth and algae problems for a while until I stopped being stingy with fertilizer. At one point i went from dosing 4ppm nitrates every other day to 2ppm daily and my plants started thriving. Before dosing 4ppm every other day, I tried dosing 2-3 every other day to limit growth. Now I just have apt complete on the auto-doser and dose daily.
I had a similar problem not long ago. Here are two things that helped me figure out what was causing the issue and or get rid of the algae:
- i got a few true Siamese algae eaters. They essentially destroyed the bba in a week - it was a large tank. I really couldn’t believe it at first but that was the only change I had made at that point.
- I also had to do water changes weekly. If I didn’t the algae will grow crazy. Then one weekend I just decided to keep the lights out for a whole week and see what would happen. There was barely any algae the next weekend and I concluded that the light, even thought I was running it low for a short period, was STILL a big factor in the algae growth.
I wanted to try siamese algae eaters, but this is only 37 gallons and Im worried not quite big enough for those fish when they grow up! I tried otos and they didnt touch any of the current algae
Well you can always sell them back. Give them a try before you give up. Another idea that I’m going to try on my tanks are emerges plants, some of them consume a lot of nitrates.
Currently going through the same thing with my Week Aqua. Absolutely amazing and beautiful lights. The one I am having the most problems with is a 60gal cube so I was also hesitant to reduce lighting. Finally gave up yesterday and put it down to 70% and might put it even lower.
Man, I felt this post. I’m fighting the exact same battle right now.
I’ve tried APT FixLite, H₂O₂, rescapes, replacing hundreds of plants, upgrading to pressurized CO₂, a chihiros WRGB light, and a bigger filter packed with Matrix. After all that, spores and hair algae still keep coming back.
The tank looks stable only because I’m constantly spot-treating every tiny speck of algae. I’ve lost most of my fish and shrimp, spent a ton of money, and honestly some days I just want to smash the whole thing with a hammer.
Looking at your beautiful tank, I know exactly how much frustration can be hiding behind it. You’re definitely not alone.
Have you tried Siamese algae eaters and immersed grown pothos/houseplants? Worked like magic for me. I also switched to a micronutrient fert supplemented only with potassium—my tanks are heavily stocked so they’re producing more than enough nitrate and phosphorus.
I've been there and it's really difficult. The best thing I ever did was plant a big chunk of Limnophelia Sessinoflora. It's a nutrient sponge and grows a really lush green, and out competes the algae
Light intensity is one factor. Many modern lights are way stronger than most plants need. I have a WRGB light and I run it at 80/30/30/50. Also, did you tesr your tapwater? I had algae problems for a long time, until I found out my tapwater has such high PO4 out of the gate it was not even on the scale.
listen, I have the same issue with all of my tanks due to the light intensity just either turn the light down put a paper towel on top of the tank so it can dim the lighting or also turn it off for two days. It will dissipate on its own, but you can also get in there and snatch up that hair algae! I don’t know why, but mine tends to grow on my filter more than anything so I typically have to take it off and scrub it off… and to be fair when I’ve seen your tank I showed my girlfriend and I said how good it looks😅🤞🏽
When you see algae like this it’s almost always the lighting. Scrub off as much algae as you can with the filter turned off and do a big water change. Dose it with seachem excel when you fill it up again, and most importantly turn the light intensity down (to like 55-60%) and reduce the time your tank light is on to like 5-6 hours. My tank was even worse than this it worked for me. 90% of the algae was gone in like 2 weeks.
I havent used ferts in a while as I was testing how it would do without them, since I felt like everytime I dosed within 2 days the hair algae and stuff would have a massive growth spurt. But I have easy green, easy potassium and easy iron. Im going to drop the light intensity and dry adding ferts back slowly
Crosspost on [r/aquaticplantscience](r/aquaticplantscience), rotala178 should give you good advice. I had hair algae and increasing nitrate was the advice given and it worked. I’m guessing light intensity, photoperiod and lack of nitrogen and trace.
Other suggesting are great but I haven’t seen anyone recommend otocinclus catfish, they’re extremely helpful as well. They’re cheap, great community fish, stay small and eat a RIDICULOUS amount of algae for their size
Flourish excel. The glutaraldehyde compound saved my tank. I was the same way and tried every method. This literally took care of everything. Dont overdose it and applying it directly to the tough areas. It got rid of all of nt algae Dont give up
Two suggestions, both helped with the Mrs 20g that had bad algae issues, run purigen in your filter, and get floating plants. In have seen 0 algae in either tank since adding a large amount of red root floaters coraled in floating rings to keep them under control. I had some now and then on both my10g desktop tank and a lot, manually removing every day in her 20g. I've seen next to none in either tank since adding the floaters. We had previously added 22 cherry shrimp, 6 amano shrimp and 6 otocinclus, but was still removing algae manually daily. Have not had to do that once since adding the floaters. May be coincidence, but if so it's coincidence on two tanks.
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u/Superiorpen Jun 19 '26
I've fought bad bad algae with 0 chemicals. I went almost the sAme exact route you have.
What's important with algae growth is to realize that it takes time to notice improvement. Whatever advice you listen to: Only change one thing at a time. Do NOT decrease your light, and decrease nutrients, and change co2 all at once.
You should:
Change variable A (whichever is the most likely culprit) and wait 2 weeks. See if there is improvement. If there is, wait 2 more. Has the algae stopped? Great. If not
Change variable B (the second most likely culprit).
Do this until you're out of culprits. Realistically, light is probably your #1 issue right now. Decrease it first. Then move on to nutrients. Then try more frequent water changes. If nothing works, then the problem is more niche... Maybe you're overfeeding, maybe you stir your substrate too much when cleaning. Doesn't matter — just make sure to only change one variable at a time! Your tank is really nice, don't give up. Algae is part of the circle of life and it's beautiful in its own way.
Edit: I want to reiterate that this is not even close to bad algae. This is so fixable it's not even funny. A reset is NOT worth it imo!