Serious Algae/Cyanobacteria Problem

Hi,

I have been having a re-occurring algae/cyanobacteria problem in my fish tanks for years now and I am really struggling to keep looking after aquariums as it has been a very expensive and time consuming battle that I seem to be losing. In this post I am going to go into as much detail as possible to ask for help to diagnose and treat the problem and fix it.

History
This historically started around 12/13 years ago with my 30l biorb tank that I had as I was growing up. I had big cyanobacteria problem in this tank. 6/7 years ago I decided to start afresh and got a 60l fish tank that I set up with a new filter (TetraTec External EX800), new plants and substrate. I cycled this properly and added the fish in, but soon the same problem kept reoccurring forcing me to do massive cleans weekly. I bought my current tank ( a 120l tank) 3 years ago, again trying a fresh restart to clear the bacteria problem, however this time I used the same filter but gave it a really deep clean using Milton solution to try to kill any bacteria/algae. I also used the same heater with deep cleans. My problems with algae/bacteria persisted and I bought a new filter around 2 years ago. This didn't help, so around 10 months ago I decided to spend a lot of money on a new filter and filter media to try to have the cleanest water possible( this is in more detail below). Nothing changed so I decided to try to get some better lights and was given two lights from a friend, but these have not helped either.

My Tank

This was taken yesterday following a 2 hour cleaning session.

My tank is 120l tropical planted aquarium. Containing 8 Lemon Tetra, 2 Bolivian Rams and 1 lemon ancistrus. The fish are all very happy with the rams regularly spawning.

The plants also thrive whilst the algae/bacteria is not growing on the leaves. I recently got given some floating plants to try to soak up excess nutrients and they worked for a short while until the algae/bacteria started growing on them. They still grow well.

Filter
I have had this set up since June 2019. The filter I use is an Oase Biomaster Thermo 250 with seachem matrix as filter media on two layers plus seachem purigen, seachem matrix carbon and rowaphos. I clean the filter once every two months, washing the media in the aquarium water from a water change.

Water
Current Water parameters;
Temperature = 27.5 C
Ammonia NH4 = 0mg/l
Nitrate NO3 = 10
Nitrite NO2 = 0
KH = 10
GH = 8
pH = 7.6
Cl2 = 0
Phosphate = 1.0mg/l (which indicates my rowaphos needs changing and I shall do tomorrow)

Every morning I add 2ml of TNC Carbon, a liquid carbon, every day (they recommend 1ml per 50l) and 12ml of TNClite Aquarium Plant nutrient that contains potassium, magnesium and trace elements but no nitrate or phosphate one a week.

Lights
I have two aquael LED lights called LEDDY TUBE 16W SUNNY. These run from 0900 until 1600 so 7 hours.

The tank is also situated on the wall between two west facing windows so it definitely gets some sunlight during the afternoon.

Maintenance
I aim to clean the tank weekly, usually at weekends, however I am often away so can be left not cleaned until the Monday or Tuesday. I scrub all the glass with a toothbrush and then use the tooth brush to clean off the rocks, wood and any algae/bacteria that has grown on the plants. I then do a water change removing 15l and focusing on sucking up the mess from the clean and the debris on the floor around the plants. I then add around 20l of water back to the tank as I would have lost around 5l due to evaporation over the week.

Occasionally I miss a tank clean for a week and the tank goes two weeks without a clean, see photos below. In these circumstances I would remove 30l of water and top up around 40l. all water is from my tap and I add a chlorine remove into it before adding to the tank.

Photo of before tank clean

Photos after clean

Photos 1 day after tank clean

As you can see the algae/bacteria grows back to quickly its hard to keep on top of it.

Please any suggestions that you make are greatly received and I am happy to provide extra info if required.

Many Thanks,
Henry

Welcome to TFF Henry.

Well, I do like a challenge! But it should be easy to resolve this--and no, I am not being funny.

First, filtration has very little to do with problem algae or cyanobacteria; filters remove solid matter but it becomes liquid and stays until you remove it via water changes, so that is one source of organics. Problem algae occurs when the balance of light/nutrients is out (for the plants). Cyanobacteria is caused by organics in the presence of light. Light is part of both, so let's start there.

Seven hours should work, my tanks are on a 7-hour day too, and primarily to avoid problem algae. But that brings us to the light intensity and spectrum, and to ambient room light. Can you give us the spectrum (CRI or Kelvin)? I don't know much about LED intensity but let's work around this before considering different lighting. A regular period each day is important, which can be achieved by a timer (you may already have this). Ambient room light is very important--for a couple of summers I always had increases of Black brush algae, and finally figured out it was due solely to the increase in daylight intensity and duration in summer. Heavy drapes solved that problem. You must reduce the ambient room light--and never have direct sunlight on the aquarium. As the tank is between windows, it may be good to get plain black construction paper for the two end walls of the tank (and on the back if no solid background now).

To the nutrients and organics. First, your water changes are way too inadequate. You need to remove 60-70% of the tank water and replace it once each week, and at one time. This does make a huge difference. Use a conditioner, nothing else. Vacuum the open areas of the substrate well during the W/C. And clean the filter--the brown/black gunk is organics and the less the better. Clean it under the tap; in a tank that has been running for several years, there are more bacteria in the substrate than the filter, and in any case, the plants take up the ammonia faster. And the fresh tap water can help too. Frequency of filter cleanings can vary depending upon the specifics, but at this point I would do it every water change (weekly) until this is under control.

The above para is the only way to deal with cyanobacteria, and it will (should) disappear after a few weeks of doing this. Light blackouts may seem to kill it initially, but the underlying cause is still there and that must be addressed. Algae will also bee discouraged by this, as it removes a major source of organic nutrients.

Many of the plants in the photos are slow-growing species (Java Ferns, Anubias). These thus require less light intensity and fewer nutrients. The above will help, but you can also increase the floating plants, but with substantial species like Water Sprite, Frogbit or Water Lettuce. Floating plants are "ammonia sinks" which means they take up a considerable amount of nutrients out of the water. They will also shade the lower plants which will discourage algae on the Java Fern and Anubias; my plants of these two always do well under a canopy of floaters.

To the fertilizers. Stop the liquid carbon; I've no idea what is in TNC Carbon (some of these like Seachem's Flourish Excel and API's CO2 Booster are glutaraldehyde, a highly toxic disinfectant that can easily kill plants and bacteria, and fish if overdosed) but with all the organics here there is more than sufficient CO2 for the plants.

The TNC Lite seems OK from what they have on their site. If you are following their instruction with one dose per week, stay the course for the present. Once you see the results of the above (it will be a few weeks, give it ime) you/we can consider more or even less, or a different product.

Byron covered most of it.

Cyanobacter bacteria loves nutrients, low oxygen levels and low water movement. It also love red and yellow light.

As Byron mentioned, virtually all your plants are slow growing varieties and don't need fertiliser, or only require a very small amount of fertiliser. I would stop using any and all fertilisers for a couple of months while this gets sorted out.

Old fluorescent light globes lose their Kelvin (K) rating as they get older but LEDs shouldn't. However, if there is not enough blue light, then blue green algae will be quite happy. Byron asked for the Kelvin rating so we will wait to find out what that is on your lights.

Your lighting time of 7 hours a day should be fine and has nothing to do with the problem. The green crap on the glass is green Cyanobacteria. The black stuff on the substrate is black Cyanobacteria. They are just different coloured forms of the same bacteria. It also comes in brown, pink, red and dark blue.

--------------------
If you feed dry food, reduce it and use frozen (but defrosted) and live foods instead.
If you put in bottom feeding pellets or wafers, stop using them for a bit and use frozen or live foods for any catfish.

--------------------
Increase aeration/ surface turbulence to maximise the oxygen levels in the water.
Increase water movement around the bottom of the tank.

--------------------
Do a 75% water change and gravel clean the substrate every day for a couple of weeks. Try to remove as much of the stuff as possible, including wiping the glass and plant leaves if you can.

Stop fertilising for a few weeks and then look for an iron based plant fertiliser and use that once a week. But don't add any fertiliser until this has cleared up.

Increase water movement and aeration.

Cut back on dry foods.

This might take a few months to clear because it has been going on for so long, but it should be easy enough to deal with once you stop using the fertilisers.

Colin_T said:

Byron covered most of it.

Cyanobacter bacteria loves nutrients, low oxygen levels and low water movement. It also love red and yellow light.

As Byron mentioned, virtually all your plants are slow growing varieties and don't need fertiliser, or only require a very small amount of fertiliser. I would stop using any and all fertilisers for a couple of months while this gets sorted out.

Old fluorescent light globes lose their Kelvin (K) rating as they get older but LEDs shouldn't. However, if there is not enough blue light, then blue green algae will be quite happy. Byron asked for the Kelvin rating so we will wait to find out what that is on your lights.

Your lighting time of 7 hours a day should be fine and has nothing to do with the problem. The green crap on the glass is green Cyanobacteria. The black stuff on the substrate is black Cyanobacteria. They are just different coloured forms of the same bacteria. It also comes in brown, pink, red and dark blue.

--------------------
If you feed dry food, reduce it and use frozen (but defrosted) and live foods instead.
If you put in bottom feeding pellets or wafers, stop using them for a bit and use frozen or live foods for any catfish.

--------------------
Increase aeration/ surface turbulence to maximise the oxygen levels in the water.
Increase water movement around the bottom of the tank.

--------------------
Do a 75% water change and gravel clean the substrate every day for a couple of weeks. Try to remove as much of the stuff as possible, including wiping the glass and plant leaves if you can.

Stop fertilising for a few weeks and then look for an iron based plant fertiliser and use that once a week. But don't add any fertiliser until this has cleared up.

Increase water movement and aeration.

Cut back on dry foods.

This might take a few months to clear because it has been going on for so long, but it should be easy enough to deal with once you stop using the fertilisers.

Click to expand...

Byron said:

Welcome to TFF Henry.

Well, I do like a challenge! But it should be easy to resolve this--and no, I am not being funny.

First, filtration has very little to do with problem algae or cyanobacteria; filters remove solid matter but it becomes liquid and stays until you remove it via water changes, so that is one source of organics. Problem algae occurs when the balance of light/nutrients is out (for the plants). Cyanobacteria is caused by organics in the presence of light. Light is part of both, so let's start there.

Seven hours should work, my tanks are on a 7-hour day too, and primarily to avoid problem algae. But that brings us to the light intensity and spectrum, and to ambient room light. Can you give us the spectrum (CRI or Kelvin)? I don't know much about LED intensity but let's work around this before considering different lighting. A regular period each day is important, which can be achieved by a timer (you may already have this). Ambient room light is very important--for a couple of summers I always had increases of Black brush algae, and finally figured out it was due solely to the increase in daylight intensity and duration in summer. Heavy drapes solved that problem. You must reduce the ambient room light--and never have direct sunlight on the aquarium. As the tank is between windows, it may be good to get plain black construction paper for the two end walls of the tank (and on the back if no solid background now).

To the nutrients and organics. First, your water changes are way too inadequate. You need to remove 60-70% of the tank water and replace it once each week, and at one time. This does make a huge difference. Use a conditioner, nothing else. Vacuum the open areas of the substrate well during the W/C. And clean the filter--the brown/black gunk is organics and the less the better. Clean it under the tap; in a tank that has been running for several years, there are more bacteria in the substrate than the filter, and in any case, the plants take up the ammonia faster. And the fresh tap water can help too. Frequency of filter cleanings can vary depending upon the specifics, but at this point I would do it every water change (weekly) until this is under control.

The above para is the only way to deal with cyanobacteria, and it will (should) disappear after a few weeks of doing this. Light blackouts may seem to kill it initially, but the underlying cause is still there and that must be addressed. Algae will also bee discouraged by this, as it removes a major source of organic nutrients.

Many of the plants in the photos are slow-growing species (Java Ferns, Anubias). These thus require less light intensity and fewer nutrients. The above will help, but you can also increase the floating plants, but with substantial species like Water Sprite, Frogbit or Water Lettuce. Floating plants are "ammonia sinks" which means they take up a considerable amount of nutrients out of the water. They will also shade the lower plants which will discourage algae on the Java Fern and Anubias; my plants of these two always do well under a canopy of floaters.

To the fertilizers. Stop the liquid carbon; I've no idea what is in TNC Carbon (some of these like Seachem's Flourish Excel and API's CO2 Booster are glutaraldehyde, a highly toxic disinfectant that can easily kill plants and bacteria, and fish if overdosed) but with all the organics here there is more than sufficient CO2 for the plants.

The TNC Lite seems OK from what they have on their site. If you are following their instruction with one dose per week, stay the course for the present. Once you see the results of the above (it will be a few weeks, give it ime) you/we can consider more or even less, or a different product.

Click to expand...

Hi Both,

Thank you so much for the replies!



The above is my lights which I have two running on a timer, so the light is regular. https://www.swelluk.com/aquael-leddy-tube-retrofit-sunny/
On the attached website it says mine produces 6500 K.

I definitely will get some black card and stick it to the sunlight corners and back of the tank. I have tried blackouts before and as you said it kills it off but doesn't fix the problem long term.

Okay, sounds like I need to get a bigger bucket ! I will up the water changes and do 60-70% changes every day for a few weeks, after that will it be okay to go back to doing them weekly? or shall I maintain the high intensity for a bit longer? I will also start cleaning the filter out weekly, and make sure I clean it under the tap. I do struggle to hoover up all the debris under the plants in the crevices and stuff, but I will try to get them as best I can.

Yep, I will stop the carbon straight away, and halt the fertiliser for now. I am happy to try to get some more plants that are a bit faster growing if you have any recommendations ? The floating plants really took off when I put them in and before long there was a cover over the whole tank about 2 inch deep! So I took some out and have been letting them grow back.

Any advice for increasing water movement around the bottom of the tank?

In terms of food I use dry food with frozen at weekends for treats, but yes I can feed frozen for the next few weeks to help I also give the ancestries some cucumber is that ok to carry on?

Thank you again for the replies I'm very grateful.

Once I have this under control should I be doing a weekly 60-70% water change and cleaning the filter? or drop it down a bit?

Henry.ager said:

The above is my lights which I have two running on a timer, so the light is regular. https://www.swelluk.com/aquael-leddy-tube-retrofit-sunny/
On the attached website it says mine produces 6500 K.

Click to expand...

That's good. I think we can leave the light now, and if nothing improves with the other changes being suggested, we might return to the light, but I doubt this is the crux of all this. Reducing the ambient daylight is going to make a big difference, I was amazed at how much the algae profited just from the additional daylight in summer compared to winter, and I had blinds (but not the blackout drapes) on the windows then.

Henry.ager said:

Yep, I will stop the carbon straight away, and halt the fertiliser for now.

Click to expand...

I know where Colin is coming from with this, but I am hesitant to suggest the TNC Lite also end, but try it. Thinking back when I had cyano in my 70g I did stop the Flourish Comprehensive for 3-4 weeks too, then recommenced. Your floating plants are high-nutrient so be careful.

Henry.ager said:

Any advice for increasing water movement around the bottom of the tank?

Click to expand...

This is not an issue. I never had cyano in tanks with sponge filters, including my 40g for three years running, and in the 70g where I did twice battle cyano it was always first noticeable next to the filter return where the flow was stronger.

Henry.ager said:

Once I have this under control should I be doing a weekly 60-70% water change and cleaning the filter? or drop it down a bit?

Click to expand...

Yes on the W/c...I have been doing 60-70% of all my tanks for years now. The filter cleaning depends; when I had canisters on my three large tanks I went by the plant response and algae. On all my tanks now, from 40g to 33g to 219g to 20g to 10g I clean the filters every water change, under the tap to get it down thoroughly. Sponge filters, and Fluval Quiet Flow on the 40g now.

Byron said:

That's good. I think we can leave the light now, and if nothing improves with the other changes being suggested, we might return to the light, but I doubt this is the crux of all this. Reducing the ambient daylight is going to make a big difference, I was amazed at how much the algae profited just from the additional daylight in summer compared to winter, and I had blinds (but not the blackout drapes) on the windows then.



I know where Colin is coming from with this, but I am hesitant to suggest the TNC Lite also end, but try it. Thinking back when I had cyano in my 70g I did stop the Flourish Comprehensive for 3-4 weeks too, then recommenced. Your floating plants are high-nutrient so be careful.



This is not an issue. I never had cyano in tanks with sponge filters, including my 40g for three years running, and in the 70g where I did twice battle cyano it was always first noticeable next to the filter return where the flow was stronger.



Yes on the W/c...I have been doing 60-70% of all my tanks for years now. The filter cleaning depends; when I had canisters on my three large tanks I went by the plant response and algae. On all my tanks now, from 40g to 33g to 219g to 20g to 10g I clean the filters every water change, under the tap to get it down thoroughly. Sponge filters, and Fluval Quiet Flow on the 40g now.

Click to expand...

Cool, thank you again for all of this. I will give it all a go and let you know how I am doing in a few weeks.

Henry.ager said:

Cool, thank you again for all of this. I will give it all a go and let you know how I am doing in a few weeks.

Click to expand...

On the W/C, this is a 120 liter (30 gallon) so you could use buckets. I use a Python on my tanks, I got this when I got my first large tank (90 g) and without it I would never have managed my 115g 90g and 70g tanks for 20 years. I'm used to it now and except for my 10g I use the Python. I have trouble carrying buckets anyway, so just as well.

Byron said:

On the W/C, this is a 120 liter (30 gallon) so you could use buckets. I use a Python on my tanks, I got this when I got my first large tank (90 g) and without it I would never have managed my 115g 90g and 70g tanks for 20 years. I'm used to it now and except for my 10g I use the Python. I have trouble carrying buckets anyway, so just as well.

Click to expand...

Wow that looks amazing I didn't know they existed! The only problem is we have a water softener for all the taps except one that I use for my fish tank and is downstairs when the tank is upstairs. Any advice for using soft water in fish tanks ?

Henry.ager said:

Wow that looks amazing I didn't know they existed! The only problem is we have a water softener for all the taps except one that I use for my fish tank and is downstairs when the tank is upstairs. Any advice for using soft water in fish tanks ?

Click to expand...

There are three issues here. First, on the soft water, if you have soft water fish species then the water can be as soft as zero. My tap water fortunately is 7 ppm GH which is basically zero, and KH zero. I only have soft water fish, mostly wild caught. The fish you mention in post #1 are all soft water species, though they are ones that can manage very well in your present water with respect to the GH of 8 dGH and a low basic pH (7.6 you said). So you do not have any issues here.

Second point though is the softener...this can be a problem for fish, depending upon how the apparatus softens the water. Many softeners replace calcium and magnesium mineral salts with sodium chloride salts (this is common salt as in sea salt and table salt). Soft water fish especially have real issues with sodium chloride (common salt) in their water, so from that aspect you are better with what you have.

Third on I assume the Python attached downstairs and the fish tank upstairs. This could work. The draining downhill would certainly have no issues (uphill I expect is basically impossible when draining) and refilling upstairs has the pressure of the taps so that should work. You do have to be careful being in two places at once though, unless you have someone to wait at the faucet to turn it off at the right moment.

Hi Byron,

Hope you're well.

I have been doing daily 70% water changes with cleaning, no CO2 and live food like you suggested and cleaning the filter out under the tap weekly. I have seen a big difference, but I am still getting quite a substantial regrowth of cyanobactaria. Over a day I will get around 1 cm of growth from the substrate upwards and also patches on plants and rocks. Over the last weekend I gave everything a thorough clean and a big water change.

Do you have any more suggestions for reducing the growth back? or shall I keep going with my daily changes. Am I still doing something wrong ?

Thanks for the help,

Henry

Henry.ager said:

Hi Byron,

Hope you're well.

I have been doing daily 70% water changes with cleaning, no CO2 and live food like you suggested and cleaning the filter out under the tap weekly. I have seen a big difference, but I am still getting quite a substantial regrowth of cyanobactaria. Over a day I will get around 1 cm of growth from the substrate upwards and also patches on plants and rocks. Over the last weekend I gave everything a thorough clean and a big water change.

Do you have any more suggestions for reducing the growth back? or shall I keep going with my daily changes. Am I still doing something wrong ?

Thanks for the help,

Henry

Click to expand...

Can you post photos?

It took me several weeks to eliminate cyano, though that was with once weekly massive water changes and reduced fertilizer/feeding.

I must say, I definitely don't agree with washing the filter in tap water every week. This seems like the exact opposite of what you want to do. You want the beneficial bacteria in your filter to be as healthy as possible so it can eat up the wastes in the tank as fast as possible.

You want to keep the flow in the filter good so it is a good idea to rinse the media about once a month. You should only rinse in used tank water. For example, when you do a water change, pull the media out of the filter and gently swish it in the bucket of old tank water.

Read this. The 2hr aquarist blog is an excellent guide to growing plants. The very fist point is literally that you need your filter media as mature and stable as possible. Rinsing the media every week in tap will absolutely destabilize your biological filter. You case seems quite extreme. I imagine you may want to use antibiotics (specific antibiotic is mentioned in the blog).

threecharacters said:

I must say, I definitely don't agree with washing the filter in tap water every week. This seems like the exact opposite of what you want to do. You want the beneficial bacteria in your filter to be as healthy as possible so it can eat up the wastes in the tank as fast as possible.

You want to keep the flow in the filter good so it is a good idea to rinse the media about once a month. You should only rinse in used tank water. For example, when you do a water change, pull the media out of the filter and gently swish it in the bucket of old tank water.

Read this. The 2hr aquarist blog is an excellent guide to growing plants. The very fist point is literally that you need your filter media as mature and stable as possible. Rinsing the media every week in tap will absolutely destabilize your biological filter. You case seems quite extreme. I imagine you may want to use antibiotics (specific antibiotic is mentioned in the blog).

Click to expand...

There are some factors to keep in mind. First, this is a planted tank, and you could remove the filter altogether and not negatively impact the system other than obviously the water flow. The point being that whether you kill the nitrifying bacteria or not, it is not going to matter. And, the basis of a stable biological system is the substrate, not the filter.

There is evidence that most if perhaps even all of the nitrifying bacteria in the filter will not be killed by chlorine. Not that it really matters given the above factor, but it is worth remembering. Plus the fact that there are considerably more nitrifying bacteria in the substrate than in the filter. In a new tank without plants, I agree the nitrifying bnacteria are primarily in the filter and are crucial. But not subsequently, and not in planted tanks if the plants are growing.

The nitrifying bacteria in the filter do not eat waste; they use ammonia and nitrite. These are not waste. The waste control bacteria are in the substrate, not the filter, though it is possible to create an unbalanced biological system where the waste control bacteria do multiply in the filter, but this kills off the aerobic nitrifying bacteria.

The blog link has some inaccurate and misleading information. There isn't much benefit in countering all that, though I could if asked.

Byron said:

Can you post photos?

It took me several weeks to eliminate cyano, though that was with once weekly massive water changes and reduced fertilizer/feeding.

Click to expand...

ive taken some tonight after the clean and I’ll post again tomorrow when I’m home from work to show the regrowth rate.

Henry.ager said:

ive taken some tonight after the clean and I’ll post again tomorrow when I’m home from work to show the regrowth rate.

Click to expand...

To be honest, I can not see any cyano in these photos. Maybe you are dealing with algae here?