# War on Blue Green Algae



## senegal927 (Dec 12, 2012)

Hello all 

Last week I found BGA all over one of my driftwood logs and on small spots on my substrate. I increased aeration and lowered my light cycle. Since this I find most of the BGA gone from the substrate and most gone from the driftwood every morning only to see it return in full force by 3pm. So I am assuming this is light related? 

I have a 40g tank with a corallife t5 41w light fixture right on the glass. I am afraid to lower my light and hurt my plants but want to keep the pressure on this ugly stuff. Any suggestions?


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## cheesehead (Jun 13, 2007)

Erythromycin if you're so inclined, 2.5 mg/liter (or 200 mg for your tank), 3 doses. I do them every other day, large water change and vacuum out as much BGA (dead/dying) as I can before the next dose.


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## Capsaicin_MFK (Nov 15, 2009)

1. Make sure your nitrates are above 0 ppm.
2. Make sure your phosphates are low, like less than 1 ppm.
3. Make sure your filter is clean and the substrate is relatively clean.
4. If all that is in check and you still have BGA, it's time for Erythromycin.


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## senegal927 (Dec 12, 2012)

Ok i'll do the suggested items. Do you recommend water changes? I could do these using R0 water if it helps. 

Would UV help at all?


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## Darkblade48 (Jan 4, 2008)

senegal927 said:


> Ok i'll do the suggested items. Do you recommend water changes? I could do these using R0 water if it helps.
> 
> Would UV help at all?


Water changes (manual removal) will help knock it back if you are not going to use erythromycin (it is a last resort anyway, since it does not remedy the underlying problem causing the algae in the first place).

No need to do water changes with RO water (unless your tap water/well water is unusual?)

UV will only kill free floating algae, and any cyanobacteria that happens to be free floating and passes through the UV filter will just be coincidental.


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## happi (Dec 18, 2009)

Capsaicin_MFK said:


> 1. Make sure your nitrates are above 0 ppm.
> 2. Make sure your phosphates are low, like less than 1 ppm.
> 3. Make sure your filter is clean and the substrate is relatively clean.
> 4. If all that is in check and you still have BGA, it's time for Erythromycin.


 
it is not related to low nitrate, even though this is what we believe and hear from others. it can also be present in high nitrate.


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## jccaclimber (Aug 29, 2011)

While I'm sure it can persist in other conditions, by BGA experience is always nitrate linked.
If I go out of town for too long and don't fertilize while I'm gone I get BGA every time my nitrates bottom out. It always goes away within a week once I start dosing nitrates, and I don't even do manual removal.
The first time I had it I tried fighting it for a couple months. It went away once I started fertilizing regularly.
Just for fun I've dosed everything except my nitrates normally, this usually makes BGA show up in around three weeks in my tank.


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## happi (Dec 18, 2009)

jccaclimber said:


> While I'm sure it can persist in other conditions, by BGA experience is always nitrate linked.
> If I go out of town for too long and don't fertilize while I'm gone I get BGA every time my nitrates bottom out. It always goes away within a week once I start dosing nitrates, and I don't even do manual removal.
> The first time I had it I tried fighting it for a couple months. It went away once I started fertilizing regularly.
> Just for fun I've dosed everything except my nitrates normally, this usually makes BGA show up in around three weeks in my tank.


how would you explain who have BGA even with high nitrates.


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## auban (Jun 23, 2012)

aphanizomen flos-aque (heterocystous cyano) and microcystis aeruginosa (nonheterocystous cyano) both grow fastest with ammonia, nitrate, and then nitrite and atmospheric N2, in that order. most cyanobacterias follow the same pattern.

the idea that cyano is caused by a lack of nitrates is like saying that humans are caused by a lack of sugar. not only can cyano use nitrates, the only better fertilizer for cyano is ammonia.

now, i know that plenty of you have experienced a direct correlation between your levels of nitrates and your amount of cyano, but i can assure you that it has nothing to do with the actual amount of nitrates, but rather what conditions the presence of nitrates produces. in a nutshell, with plenty of nitrates, plants produce more proteins, which cause them to pull more iron, phosphorus, and various micro-nutrients out of the water. nitrate is used to make proteins. micronutrients are needed for organelles...

get where i am going with this? if you are blasting your tank full of nitrate, but are not giving your plants light, they wont be growing. the original balance of nutrients that allowed cyano to take hold will not change. cyano is capable of surviving complete blackout by nitrogen fixation. it lives off of the nitrogen in the atmosphere. when the lights are off, the only thing it needs to keep from dying is plenty of oxygen. what it cant do, however, is grow if it doesn't have everything it needs. if the plants are taking up all the less obvious nutrients, the cyano doesn't grow and doesn't spread. 

i hope i am making sense here. for the longest time i have wondered at how people can adamantly disagree while observing two halves of the SAME phenomenon. 

because of cyanos unique properties, there are many valid methods of getting rid of it. 
*1*: increase CO2 to boost plant growth. the goal is to strip the water of micro-nutrients that the cyano needs.

*2*: increase nitrates. similar goal to method one

*3*: blackout: doesnt always work, but reduces the energy cyano gets from nitrogen fixation by about 90%. can kill it out right if oxygen levels get too low, which often happens underneath the mucilage sheath surrounding the cyano during prolonged darkness.

*4* increase carbonates. this works by a couple ways. one, at higher ph phosphorus is more likely to coprecipitate out with carbonates, removing it from the water. two, many plants can use carbonates nearly as efficently as they can CO2. dispite injecting my tanks with a lot of CO2, i still see a big difference in shortly after water changes, or when i add more aragonite. plants grow, cyano starves.

*5* add antibiotics. it works the same way on cyano that it does on any other bacteria. it is pretty much 100% affective, but be prepared to do a couple water changes if you have a lot of cyano. when it dies, it dies fast.

*6* this is an oddball method, but i have had success with it. if you have something that is too delicate for you to use chemicals, and you dont want to turn the lights off because you need the water to be as saturated with oxygen as possible, you can shine a UV germicidal bulb on it. i know there probably arent a lot of people who would ever end up in a situation where they cant afford to use any of the conventional methods, but i find myself in those situations whenever i am trying to observe different aspects of the general ecology in my tanks. microscopic en-vivo observations often depend on maintaining high oxygen levels, but at the same time preventing a small field of view from being obscured. i use a focusable UV-C laser for this. works like a charm. it doesnt take much of an exposure, so using a germicidal bulb the same way you would if you were sanitizing vegetables is usually enough to make quite a difference on the cyano.


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## jccaclimber (Aug 29, 2011)

happi said:


> how would you explain who have BGA even with high nitrates.


I have seen BGA in a tank which on average has high nitrates, but not in certain areas. Usually it's burried in a pocket of riccia, and in that case adding some kno3 on top of the riccia (floating in a corner) took it out in a couple days.

Please note that I started with "While I'm sure it can persist in other conditions". I wouldn't be surprised if there is a strain that survives in higher nitrate conditions. I am however refuting your claim that BGA and nitrate levels are "unrelated". I can induce it with no change other than low nitrates, and I can then remove it with no change other than adding nitrates. I have done this several times. To me this implies a relation.


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## houseofcards (Mar 21, 2009)

jccaclimber said:


> I have seen BGA in a tank which on average has high nitrates, but not in certain areas. Usually it's burried in a pocket of riccia, and in that case adding some kno3 on top of the riccia (floating in a corner) took it out in a couple days....


So your saying that the KNO3 asks as an algaecide in itself, sorta like Excel. 

Since BGA exists in tanks with high or no KNO3 it was always my believe that raising KNO3 increases uptake in some lacking systems and it's that additional uptake that knocks out the BGA, similar to the way increasing CO2 will reduce other algae, etc.


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## micheljq (Oct 24, 2012)

If I can talk of my stange little encounter with cyano, I had cyano for months.

- Dosing nitrates did nothing at all.
- My cyano liked water changes and had a little boom after water changes.
- Started CO2, cyano did grow like mad, dosed nitrates again to no avail.
- Turned off CO2, began dosing nitrates and phosphates with EI low light method, cyano began disappearing on second week, after fourth week it completely disappeared, meanwhile I left my stem plants growing and growing without trimming.

My guess is that my mistake was to not dose phosphates, in my particular case.

Michel.


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## plantbrain (Dec 15, 2003)

happi said:


> how would you explain who have BGA even with high nitrates.


I've wondered this as well, there may be more than one way to induce algae/BGA.

We cannot rule out that there are NOT other potential reasons.
Dirty neglected tanks etc, plus there's adult algae there already, so if you kill that, then add more NO3, it does not come back. But if you just add more NO3, it'll persist.

Perhaps a lot of organic loading, lower O2 etc.
Not just low NO3 or bottoming out NO3 for extended periods.


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## plantbrain (Dec 15, 2003)

auban said:


> aphanizomen flos-aque (heterocystous cyano) and microcystis aeruginosa (nonheterocystous cyano) both grow fastest with ammonia, nitrate, and then nitrite and atmospheric N2, in that order. most cyanobacterias follow the same pattern.


We only have one pest genus: Oscillitoria. They really are not heterocyst forming BGA's, but they might still fix N2 gas nonetheless. Phormidium I found in a few samples also, semi rare though and the tank was nasty. 



> the idea that cyano is caused by a lack of nitrates is like saying that humans are caused by a lack of sugar. not only can cyano use nitrates, the only better fertilizer for cyano is ammonia.


I do not think any said they cannot use NO3, we have stated that BGA is correlated with a reduced NO3 level(under 5ppm), to the point where it starts affecting plant growth(eg, limited N for plants). Limiting PO4 does not cause any algae bloom really(GSA mostly), so that was popular in the 1990's and not NO3 limiting. 

This(lower NO3 below 5ppm(?) appears to induce Oscillitoria in planted tanks. There is no way to limit nutrients for BGA's in planted tanks, their demand for nutrients are minute compared to plants.

Indirectly, plant growth appears to suppress algae.
Perhaps when BGA's detect lower O2 in the root zone, or the vegetative cone, they will bloom and grow. Plants are not growing, it's a good time to grow. Otherwise, they just sit there. Mostly between the glass and gravel below the soil a little bit.

Once the NO3 drops, then they bloom.



> i hope i am making sense here. for the longest time i have wondered at how people can adamantly disagree while observing two halves of the SAME phenomenon.


I do not think ANYONE has ever suggested that we are limiting BGA with nutrients.



> because of cyanos unique properties, there are many valid methods of getting rid of it.
> *1*: increase CO2 to boost plant growth. the goal is to strip the water of micro-nutrients that the cyano needs.


So you think that BGA are now micronutrient limited, whereas you argued above that they cannot be N limited? Leaching from plants provides ample supply, a few decayed leaves is all that is needed.

So what ppb of micro nutrients are limiting to Oscillitoria?
Any ideas? Estimations?




> *3*: blackout: doesnt always work, but reduces the energy cyano gets from nitrogen fixation by about 90%. can kill it out right if oxygen levels get too low, which often happens underneath the mucilage sheath surrounding the cyano during prolonged darkness.


BGA does not get energy from N fixation, it's a energy expenditure(i think you meant to say this). Not that Oscillitoria even needs to fix N2 gas in any planted tank, there's always non limiting N in a planted tank for most any algae or BGA.

If not, we should easily be able to water change algae into submission for a few days before the plant reserves are depleted. Generally that leads to worse problems(again, back to poor plant growth as the root cause, not nutrient limitation of algae/BGA). 



> *4* increase carbonates. this works by a couple ways. one, at higher ph phosphorus is more likely to coprecipitate out with carbonates, removing it from the water. two, many plants can use carbonates nearly as efficently as they can CO2. dispite injecting my tanks with a lot of CO2, i still see a big difference in shortly after water changes, or when i add more aragonite. plants grow, cyano starves.


I know of no submersed plant that has the same rate of growth at high KH as they do at high CO2. CO2 is greatly preferred in each and every case. It's an added allocation and energy expense to use HCO3 vs CO2. 

I know of many aggressive weeds that use HCO3 as a carbon source indirectly, but it's still an energy expense in all cases. 

I add lots of PO4, roughly 15 ppm a week from KH2PO4, my KH is low, about 20 ppm. BGA issues? I do not have any. I tend to care for my tanks well, however clients often are not consistent.

So when they stop dosing, I'll get call about algae, BGA etc.
CO2 tank ran out: green algae mostly. Low CO2= BBA
NO3 doser stopped= bga.

BGA is present in all my tanks, but it's regulated to the gravel below the surface on the glass nearest to a light source. It'll stay there for years, so it's not a question of having it inoculated or present, rather, is it a management issue?

No, not in the least.

We can rule out things like PO4, low KH, etc as direct factors.
I think you might be on to something with O2 however.

When plants are limited, mild moderate or strongly, then they reduce growth and also reduce O2 evolution from leaves(veg cones/apical meristems etc) and also roots. They do not release much O2 at night. Indirect growth reduction might be a trigger for many species of algae.

Bacterial links to the O2 levels might be a player also. No one really knows.



> *6* i use a focusable UV-C laser for this. works like a charm. it doesnt take much of an exposure, so using a germicidal bulb the same way you would if you were sanitizing vegetables is usually enough to make quite a difference on the cyano.


Well, that is a NEW one, lasers.


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## jccaclimber (Aug 29, 2011)

houseofcards said:


> So your saying that the KNO3 asks as an algaecide in itself, sorta like Excel.
> 
> Since BGA exists in tanks with high or no KNO3 it was always my believe that raising KNO3 increases uptake in some lacking systems and it's that additional uptake that knocks out the BGA, similar to the way increasing CO2 will reduce other algae, etc.


Not quite. I think that KNO3 (well, NO3- to be clear) being available provides a more hospitable environment to other things which outcompete the BGA. Most things can out compete it, but those same things cannot live without some nitrates. The absence of nitrates leaves a gap in which few things can thrive. One of the things that can thrive there, but isn't particularly adept at competing elsewhere, is BGA.


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## auban (Jun 23, 2012)

plantbrain said:


> We only have one pest genus: Oscillitoria. They really are not heterocyst forming BGA's, but they might still fix N2 gas nonetheless. Phormidium I found in a few samples also, semi rare though and the tank was nasty.
> 
> i have also found lyngbya. i think its commonly misdiagnosed.
> generally it wont form a thick mat in a tank, but i have seen it growing entangled in plants before. it can make for quite a mess...
> ...


of all the fascinating aspects of an aquarium, none bring me such felicity as the deceptively complex simplicities of our microfauna.


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## Rob in Puyallup (Jul 2, 2009)

Uhhhh... In the end there's still some bga to get rid of of. ;-) 

Sent from my Samsung Galaxy S III using Tapatalk 2


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## auban (Jun 23, 2012)

Rob in Puyallup said:


> Uhhhh... In the end there's still some bga to get rid of of. ;-)
> 
> Sent from my Samsung Galaxy S III using Tapatalk 2


lol

well, if no one thing works, i would suggest a combination of the easiest things first. ie, increase nitrates and raise CO2 and reduce photoperiod. when its gone, you can start slowly lowering CO2, increasing photoperiod, back off on nitrates, etc, until you find out what the threshold is for your tank. 

the only thing i dont like about antibiotics is that it doesnt engender a change that is capable of preventing the problem from coming back. it may never come back, but if it does you will be back to square one...

i think we jump the gun a bit when we tell people a quick fix way of treating it without explaining why it might work.


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## danielt (Dec 19, 2012)

I cannot help myself from observing that we're trained by microorganisms on how to take care of our plants 

I had a similar lesson taught by BBA in my tank.


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## senegal927 (Dec 12, 2012)

Update on the tank and BGA...


I cleaned the canister filter
Removed some dead leafs
Did a 45% water change
Turned on my UV
Used Hydrogen Peroxide target dosed on BGA areas
It's been about a week now and it's worked great! I do have small spots of BGA still but 90% of it has died! Since doing all this work my nitrates have come up from 5PPM to 10-15PPM, not sure if that helped at all. 

I will update again in a couple days....

Thanks for all your advice...


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