# Cyanobacteria in NPT aquarium



## Z1234 (Oct 25, 2016)

I need some advice on cyanobacteria (BGA).

One of my tank got infected with it badly. I don't know what to do with it. I remove as much as I can, but it keeps quickly coming back. Very annoying.

Fish and shrimps are healthy and have always been in this tank. Plants are in OK condition, but I think cyano is starting to hurt them. Tank was set up 6-7 months ago and all was OK before the cyano came in. (I put in a plant which was likely heavily infected.)

My NO2 and NO3 tests shows 0. Normally I don't dose the tank with liquid ferts (it's an NPT...), but I tried to add KNO3 to the tank since the cyano outbreak. Did not help.

I cannot really see any other algae in this tank, but cyano. There are some diatoms though, even though my lights are on 10-12 hours (T5). Water is a very little bit cloudy, but not too bad at all. (Heterotroph bacteria?)

What should I do?

I think cyano starts to hurt my plants and also there might be a risk for fish / shrimps due to the toxins they may produce.


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## hoppycalif (Apr 7, 2005)

Does direct sunlight hit the tank anywhere? I usually get cyanobacteria (BGA) where a sun beam hits the tank every day. Since I have been keeping my tank where the sun never shines I haven't had any cyano.


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## Z1234 (Oct 25, 2016)

hoppycalif said:


> Does direct sunlight hit the tank anywhere? I usually get cyanobacteria (BGA) where a sun beam hits the tank every day. Since I have been keeping my tank where the sun never shines I haven't had any cyano.


There is no direct sunlight. In fact, I have 2 tanks that gets some sunlight but no cyanobacteria there.

Earlier with some tanks I saw a little cyanobacteria between the glass and the substrate, but that did not really disturb me.

But this time its different. It's on the plants, ground and it keeps coming back.

O2 levels must be OK in the tank. Fish have never shown any sign of distress.


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## dwalstad (Apr 14, 2006)

BGA can be nasty. It certainly will hurt the plants, so I would keep after it. The cloudiness may be due to dying plant matter releasing organic compounds that are stimulating bacterial growth in the water.

I would clean the tank as best you can with hand removal of the BGA slime. Then treat the tank with antibiotics erythromycin or kanomycin. The dying algae will release inhibitory stuff, so afterwards I would do a big water change or put fresh charcoal in the filter.

You may have to make adjustments so that it won't come back. If you have healthy plants in another tank, you might consider sticking some in after the treatment. And maybe this tank needs _more_ light? I advocate a 12-14 hour day with a 3-4 hour afternoon siesta (lights off) to better control algae and stimulate plant growth.

Good luck!


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## Z1234 (Oct 25, 2016)

dwalstad said:


> BGA can be nasty. It certainly will hurt the plants, so I would keep after it. The cloudiness may be due to dying plant matter releasing organic compounds that are stimulating bacterial growth in the water.
> 
> I would clean the tank as best you can with hand removal of the BGA slime. Then treat the tank with antibiotics erythromycin or kanomycin. The dying algae will release inhibitory stuff, so afterwards I would do a big water change or put fresh charcoal in the filter.
> 
> ...


Thank you for the advice. I am getting really annoyed with this stuff. No matter how much I siphone out, it comes back in several days.

My lights are not very strong, I have 2 relatively old T5 neon tubes. Originally the aquarium came with 4 tubes, because its relatively large ~500 liter. I have always used only 2 lights with this aquarium and plants produced great growth, especially in the first 4-5 months or so. Now growth rate has been reduced.

The lights has been continuously ON for 12 hours for 3 weeks now. Before BGA (and some diatoms) came, I also used the siesta regimen, but when I saw the diatoms appearing I left the lights on for the entire day. Diatoms are slowly, but steadily disappearing now (shrimps eat it...).

Adding KNO3 did not make any difference for me, BGA keeps coming back. Before I added KNO3, my test kit showed 0 NO3- (and 0 NO2).

The plants are still showing some growth, however, had I stopped removing BGA it would probably cover everything. Good thing is, that it's easy to remove the cyanobacteria with a siphone; I do not dare to touch that nasty stuff with my hands 

I'll go and see a veterinary today; only they can provide antibiotics if they decide so. Part of the issue here, that the veterinary nearby do not have aquarium experience here.

I was even thinking of a "blackout" treatment as a last resort, but I really do not want to risk loosing any fish / shrimp. I have heard of shrimp / fish loses even in a super clean High Tech tank with gravel substrate; My NPT is (of course) dirted and much more organic matter in it. I guess this would increase the risks had I chosen this route.

I know that cyanobacteria is everywhere; However I did put a plant which was cyano infected (I tried to remove it as much as I could) to this tank back then. Maybe this is what started the whole issue for me?


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## dwalstad (Apr 14, 2006)

Z1234 said:


> I know that cyanobacteria is everywhere; However I did put a plant which was cyano infected (I tried to remove it as much as I could) to this tank back then. Maybe this is what started the whole issue for me?


If you cannot get the antibiotics, take heart. Sometimes BGA will just go away suddenly--like magic.

Just keep removing it. I never minded pulling it out by hand.

I would consider playing with the light a little. You may just need to get the plants growing better. You can be sure that there is BGA in your other tanks, but the plants in those tanks are somehow keeping it under control.

I can't imagine what KNO3 would have to do with BGA. Another "home remedy."


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## Z1234 (Oct 25, 2016)

dwalstad said:


> If you cannot get the antibiotics, take heart. Sometimes BGA will just go away suddenly--like magic.
> 
> Just keep removing it. I never minded pulling it out by hand.
> 
> ...


I've read on many forums that BGA may prefers low nutrient environments and some suggested KNO3.

This tank is only 6 months old, I guess there should be enough Nitrogen in the substrate for the plants. Every time I tested the water in my tanks, I always got 0 NO3-, I guess this is "normal". Thank is not over filtered, that's sure and there is quite some fish.

Anyway, I dumped in quite some KNO3 and it did not do anything with BGA for me, it kept coming back like nothing happened.

I have never seen such aggressive BGA before. In earlier tanks occasionally I noticed a little between the glass and the substrate, but I never payed to much attention.

This time, even if I removed as much as I could, after a week many plants were covered again.

One thing I can tell. It surely looks like Erythromycin is not cyanobacteria's best friend.

Now plants look reasonably good to me. All fish and shrimp are healthy and have been since the tank was set up.


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## micheljq (Mar 25, 2013)

Z1234 said:


> My lights are not very strong, I have 2 relatively old T5 neon tubes. Originally the aquarium came with 4 tubes, because its relatively large ~500 liter. I have always used only 2 lights with this aquarium and plants produced great growth, especially in the first 4-5 months or so. Now growth rate has been reduced.


Hello, maybe the tubes must be replaced, with age their luminosity diminishes, and their specter degrades. Hence, less plant growth and more cyano growth.

Michel.


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## skix (Apr 17, 2017)

I've had great success with ultralife blue green slime remover. Fish and nerite were not harmed, cyano gone and I haven't seen it since. 

Sent from my SAMSUNG-SM-N910A using Tapatalk


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## Z1234 (Oct 25, 2016)

Almost a month has passed and there is no sign of cyano coming back. Thanks for the advice. All fish, snails and shrimp are healthy. 

Lights are ON for 10-11 hours with a ~4 hours break in the middle. There is a little green spot (dust?) algae growing on the glass, even far away from the light source. This tells me there is enough light. Plants are growing good and they look healthy. There is quite a good plant mass in the aquarium.

However, there is still cloudy water that does not want to go away. I did some water change but it did not really help on this. There is no biological filtration in this tank, should I add a small filter? There is a little mulm on the ground, which I tried to remove during water changes. Does not seem to be too much for me.

(water in my other tanks are fully transparent without any filter... ... but this one has more and larger fish, ~10 rainbows + around 15 smaller fish in ~500 liter)


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## Z1234 (Oct 25, 2016)

Ok, nearly 2 months have passed and there is absolutely no sign for BGA coming back.

All fish, shrimp, snail survived the treatment (as much as I can tell).

Plants look OK:










Thanks for the advice!


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## dwalstad (Apr 14, 2006)

Wow! What a beautiful tank! You have a masterpiece.


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## greyuriel (Apr 22, 2017)

What is growing on the rocks? It's lovely.


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## Z1234 (Oct 25, 2016)

greyuriel said:


> What is growing on the rocks? It's lovely.


I have no clue. I think it is not cyano and that makes me happy . I occasionally see very small bubbles coming out of it, so I guess it is photosynthesising.


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## hoppycalif (Apr 7, 2005)

Very nice looking tank! Whatever you are doing, keep it up!!


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## DutchMuch (Apr 12, 2017)

Is that stargrass I see in there?


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## Z1234 (Oct 25, 2016)

DutchMuch said:


> Is that stargrass I see in there?


Yes, that's stargrass. Sometimes the rainbowfish like to chew on it a bit...










Stargrass is one of the plants the grows like crazy in my NPTs in the beginning (first several months), but then slowly fades away and other plants take over... Maybe because it does not have that much roots (nutrients?) or it just does not tolerate as CO2 levels get lower with time? I don't know.

I have fairly hard water.


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## DutchMuch (Apr 12, 2017)

I always like seeing pictures of stargrass in its own, large area as to where it can grow really big and smoothly. Something about that plant in a carpet (kind of) makes me like it so much.


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## Z1234 (Oct 25, 2016)

All right. Around 5 months have passed and there is absolutely no sign of any cyanobacteria.

Tank is happy:










So are the fish:


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## DutchMuch (Apr 12, 2017)

You need to post your tank on both aquascaping world forum & BarrReport. 
Your tank is one of the few NPT's I actually love seeing pics of, irl I cant imagine how amazing it looks. Plus the pics of your tank are just great themselves. You need to update us on all forums so we can all follow and learn from you because we are obviously missing something here. 
Fantastic Job, amazing.
Nate


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## dwalstad (Apr 14, 2006)

Gorgeous tank and great picture. It looks like the beginning of a movie about the Cosmos.

What I really admire is that you have used the concept of the "Aerial Advantage" to good effect. All those roots from that huge mass of floating plants are sifting the water for nutrients, preventing algal growth and protecting the submerged plants below.

Wonderful!


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## Z1234 (Oct 25, 2016)

dwalstad said:


> What I really admire is that you have used the concept of the "Aerial Advantage" to good effect. All those roots from that huge mass of floating plants are sifting the water for nutrients, preventing algal growth and protecting the submerged plants below.


Thank you all for the kind words.

In fact, I have one question to the experts that bugs me.

A little bit of background:

This 460 liter (~100 gallon) NPT is nearly one year old. I used dirt from the yard that (I guess) is not very rich in nutrients. Filtration is rather minimal, even though I have an external filter, it is rated for ~60 liter aquariums only. (for ~half year there was no filter at all.) Water changes are infrequent, maybe once every 2 months say 20%? I really do not keep track of this. Water is very hard.

Now to the question. As this tank is getting one year old, at some point it was not really able to maintain the Pistia (Stratiotes) population. This picture shows better what the current amount is:










I guess it is somewhat normal that with time some larger floating plants do not get enough nutrients from fish food in an NPT. Even though the dirt still contains plenty of nutrients, the water column may become lean with time. Pistia uses relatively a lot of nutrients. (Is it even used for wastewater treatment?)

So what I did, -which might not have been very smart - I sticked some fertilizer sticks deep in the substrate closer to larger plants. The fertilizer sticks are cheap and contain quite some nasty stuff:

*9% Total Nitrogen in Ammonia Nitrogen form (!!!)*
7% P2O5 total phosphate, out of this 5% P2O5 soluble in ammonium citrate, 2% soluble in water
8% K20 total kalium oxide, 2% water soluble

After this, Pistia started to spread quickly. It stayed small, but even the small ones were multiplying.

How bad idea is to use these sticks?

I guess some nutrients (ehrm ammonia?) may have spread into the water column which in turn boosted Pistia?

I was very closely monitoring fish and shrimp, but they all seemed to be happy like nothing happened.

The tank is large and I do not disturb the substrate. Is it OK every now and then (say every 6 months) I stick 1-2 sticks to the substrate? Or is it just too risky?

I would only attempt this if reasonable Pistia population is present, maybe that's saving the fish from poisoning?

(ps. I found NPTs very healthy for fish. The tank is only 1 year old, but many of fish and shrimp in it is much older.)

Or is my approach not right? Maybe I should just let the NPT "self regulate" itself and let the unnecessary amount of floating plants (from fish waste perspective) to disappear?


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## dwalstad (Apr 14, 2006)

How can one possibly argue with success! 

If the sticks work this well, I may try them in my own tanks. I have found that floating plants don't do well after a year or so in my tanks. Sticky problem. Maybe, you have found an easy solution. I don't particularly like liquid dosing, as it can stimulate algae, but sticks in the substrate I can live with.

Thank you for posting.


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## Z1234 (Oct 25, 2016)

dwalstad said:


> How can one possibly argue with success!
> 
> If the sticks work this well, I may try them in my own tanks. I have found that floating plants don't do well after a year or so in my tanks. Sticky problem. Maybe, you have found an easy solution. I don't particularly like liquid dosing, as it can stimulate algae, but sticks in the substrate I can live with.
> 
> Thank you for posting.


Thank you for the feedback 

I can not stop myself posting a few more pictures here:

1 year old Walstad, 460 liter (aprox 120 gallon):




























And the start ~1 year ago:










Yes, that messy stuff is dirt straight from the yard. No mineralization, no hocus-pocus, just dug it out and threw it in.

The cap is much smaller basalt pebbles.


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## Skizhx (Oct 12, 2010)

Great tank, and a great example of what can be accomplished without overthinking things!

Tough call on the fert sticks. I've suspected them of resulting in algae outbreaks a few times, and have little interest in giving them any more chances to redeem themselves. 

At least fert salts are a little more predictable in a way. Of course then the issue is putting nutrients directly into the water column where the algae wants it... But that's also where the pistia wants it...

Maybe just pull a clump out and ask "where do you see yourself in 5 years?". Tough decisions...


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## dwalstad (Apr 14, 2006)

Z1234;940906 Yes said:


> Beautiful tank and nice pictures. Thank you. You've found a perfect system. That mass of floating plants should keep this tank humming for many years.
> 
> Do you know what chemicals your stick fertilizers contained? I ask this because I would like to avoid ones that have a lot of sulfate salts.


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## Z1234 (Oct 25, 2016)

dwalstad said:


> Beautiful tank and nice pictures. Thank you. You've found a perfect system. That mass of floating plants should keep this tank humming for many years.
> 
> Do you know what chemicals your stick fertilizers contained? I ask this because I would like to avoid ones that have a lot of sulfate salts.


I double checked the label, and there is nothing containing sulfur in it.

"9% Total Nitrogen in Ammonia Nitrogen form (!!!)
7% P2O5 total phosphate, out of this 5% P2O5 soluble in ammonium citrate, 2% soluble in water
8% K20 total kalium oxide, 2% water soluble"

If I recall right from the book, NH4+ binds to soil particles to some extent, and also it is deep in the substrate (say 4-6 cm deep from surface). It's also worth mentioning that I have hard water, so (unfortunately) that shifts the NH4+ NH3 ratio towards NH3?

Anyway, that amount of Pistia should pick up NH4+ in water like candy. I guess. Hopefully


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## dwalstad (Apr 14, 2006)

Thank you. I'm inspired now to look for sticks to use for my potted plants.

I think that all your assumptions about ammonia are right on. They're so lucky to have such a smart gardener. 

Again, nice work! It is a personal pleasure for me to see healthy fish and such a magnificent floating plant cover.


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## Z1234 (Oct 25, 2016)

dwalstad said:


> Again, nice work! It is a personal pleasure for me to see healthy fish and such a magnificent floating plant cover.


Fish and shrimp health is outstanding in this tank. Even though this is only one year old, many of the fish lived for years in another NPT (Walstad tank).

Very, very rarely, when a fish dies, I usually contribute it to its age.

This is somewhat tricky, I use the internet to look up the expected lifespan for species. However, I doubt that the data is very accurate there in all cases. (For example amano shrimp life span according to google is 2-3 years only, I think all of mine is older than this.)

Do you guys know a reliable source for shrimp / fish life expectancy?

A word of warning, when I set up this tank, I used an eheim surface skimmer in the very beginning for a short period of time. That thing will kill small fish (I lost 3 before I realised the issue!) because they can swim/fall inside it. Design failure.

(Regarding to fertilizer sticks in the substrate: this was the first time I tried and normally this is not needed because dirt should have enough nutrients. Also this is risky, it is very well possible that I avoided poisoning because of the large amount of floating plants. After I put the sticks in, I was paying attention to observe fish and take action if needed. Anyway, probably it's better not doing this at all?)


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## Skizhx (Oct 12, 2010)

I'd just interpret life expectancy as a rough approximation of the average to be taken with a grain of salt.

It's going to be highly variable because in a lot of cases they're outliving their expectancy in the wild, inbreeding factors in captive populations, stresses from transport and 'holding', anecdotal data, I'd imagine dietary differences, etc.


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## buceborneo (Apr 15, 2014)

Add little dossing hydrogen Peroxide, use syringe injection to area that infected cyanobacter and others algae

Sent from my Redmi Note 4 using Tapatalk


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## Z1234 (Oct 25, 2016)

buceborneo said:


> Add little dossing hydrogen Peroxide, use syringe injection to area that infected cyanobacter and others algae
> 
> Sent from my Redmi Note 4 using Tapatalk


I don't really want to torture the fish with such a procedure. H2O2 is a strong oxidizing agent and non selective.

Fortunately the BGA went away after the erythromycin treatment and since then I have not seen any sign of it. If one plans to go this direction, talk to your vet before (check if this option is possible at all in your country). This was the last attempt (other than taking the tank apart) for me and worked.


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## dwalstad (Apr 14, 2006)

I saw some Erythromycin tablets in a pet store in Virginia last week. I've used Erythromycin and/or Kanomycin when nothing else will work. Good stuff!


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## zolteeC (Dec 26, 2017)

This is just an update. (I am the original poster, but lost my account so I had to re-register using different nick name.) The tank is fine and absolutely no sign of cyano (BGA) coming back. More than half year have passed since I did the Erythromycin treatment which nuked the thing out quickly.

I have had to remove the floating plants because there is not enough nutrients in the water column any more to support them.










Tank is around 1.5 years old now.


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## DutchMuch (Apr 12, 2017)

looks very nice


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## zolteeC (Dec 26, 2017)

DutchMuch said:


> looks very nice


Yes, I am quite happy with the situation now. Maintenance needs are minimal and both shrimps and fish are healthy.









(Hard Water NPT, tank is a bit more than 1.5 years old)


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## dwalstad (Apr 14, 2006)

Wow! A large NPT that looks like this after 1.5 years is quite an accomplishment


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