# BGA keeps coming back, help!



## DJKronik57

So I'm at the point of pulling out my hair. I've had outbreaks of BGA before, but it always was just a little spot here or there that went away on its own, or if not with Maracyn treatment.

Now, it is everywhere in my 46 gallon and it just keeps coming back. I first beat it back with a Maracyn treatment, following the dosage on the package. But a week or two later, it was back with a vengeance. Then I tried a week blackout. Looked a little weaker, but so did all my plants, and it bounced right back along with them. Finally, I tried a week blackout, followed by a Maracyn treatment, along with hydrogen peroxide spot treatment. I thought I had it licked, and it stayed away for a month, but now it's all over everything all of a sudden. I'm at my wits end and have no idea what's causing it.

What's causing these repeat outbreaks, and is there anything I can do about it?

Stats:
Light - 96 watts 8hrs
Ferts- Pressurized CO2, 4bps; NPK and traces dosed daily (nitrates are never 0)
Circulation - Eheim 2217 plus a powerhead (strong current throughout the tank)


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## Tex Gal

It's usually caused by low nitrates. You're probably killing it with the MaracynII but not stopping the root cause. Try upping your nitrates and it should go away on its own.


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## DJKronik57

Tex Gal said:


> It's usually caused by low nitrates. You're probably killing it with the MaracynII but not stopping the root cause. Try upping your nitrates and it should go away on its own.


That's what I thought too, TexGal. But unless my plants are using much more nitrates and my test kit is off, it can't be the nitrates. My nitrates are regularly around 20-30ppm, and I've tried dosing 1.5 teaspoons of KNO3 every day (which should bring the concentration to around 30ppm in one dose), with no impact.

Could it be an imbalance in another fertilizer? Maybe phosphate? Either way, my plants are doing OK, but not growing like weeds, so I suspect something is off.

Oh, and I've also been using Maracyn, not MaracynII, since that's what I've seen recommended for BGA. Is that not true?


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## Seattle_Aquarist

Hi Andrew,

I posted this in May, but your situation sounds so much like mine that I thought it might help. It was an article on Cyanobacteria (BGA) that I did for our GSAS newsletter in May.



> "Last month I mentioned that I had a "dirty little secret". I explained that I did not bring plants to the March meeting because I have been fighting cyanobacteria, also known as Blue-Green Algae (BGA), in one of my tanks and I didn't want to share it with others. After six weeks of trying different methods I seem to be making major headway and will share what is succeeding for me.
> 
> As I write this it has been exactly one week since I finished treating an outbreak of BGA in my 30 gallon aquarium. I believe it started because I let my nitrates (NO3) get too low and missed a couple of water changes. In addition I hadn't cleaned my canister filter for several of months so debris had built up and the flow and circulation had dropped in the tank. Any or all of these conditions could have been the cause for my outbreak.
> 
> Here how I got rid of it. First I worked on the causes. *I cleaned my canister filter* and added an airstone (I would have used a Koralia Pump or powerhead if I had one) to increase circulation. *I increased my fertilizer dosage to 1/8 teaspoon (tsp) of KNO3 (potassium nitrate) and 1/64 tsp of KH2PO4 (monopotassium phosphate) per 10 gallons daily*. Lastly I i*ncreased my 33% water changes to twice a week.*
> 
> Next I went to work on the algae. I siphoned and manually removed as much of the BGA off of the substrate, plants, and hardscape as possible and cleaned the glass. Most of the easy-to-replace plants I threw out. I removed most of the hardscape from the tank, scrubbed it, rinsed it, and put back in place. It was very important to remove as much BGA as possible before doing the next step to minimize oxygen depletion, and fish death, from dying algae.
> 
> I treated the BGA with Hydrogen Peroxide 3.0% (stabilized) solution. Hydrogen Peroxide (H2O2) is available at most grocery stores, pharmacies, and drug stores. I also picked up a 10 ml dosing syringe (for oral dosing of medications) at the drug store when I picked up the H2O2.
> 
> I always did this part of the treatment when I knew I was going to be around for at least a couple of hours afterwards so I could watch my fish for signs of distress. *I only treated the tank after the lights (about 2 WPG compact florescent) had been on for at least two hours so photosynthesis was occurring at its' maximum in the BGA.* I found that the BGA reaction to the treatment was strongest, and fastest, in the areas of the aquarium with the brightest light (and the most photosynthesis).
> 
> I turned off my filter about 5 minutes prior to treatment to minimize water movement. I dosed the 3.0% (stabilized) H2O2 at the rate of 1.5 ml per gallon of water volume (my 30 gallon tank has 24 gallons of water in it). I put the H2O2 in a glass, filled the 10 ml syringe, stuck my hand in the tank, and s-l-o-w-l-y "painted" the areas where the BGA was heaviest with the thickest "clumps". I added the H2O2 at a rate of about 10 ml per minute so as not to stress the fish too greatly.
> 
> The effect was rapid and dramatic. After several of minutes the areas of BGA I had "painted" with the H2O2 began to bubble (gas) and started to turn a rusty brown. After about 30 minutes the "painted" areas were bubbling intensely and had turned a definite brown color while other areas of the tank (where I had not "painted") were also bubbling (but not as intensely) and starting to turn rusty brown. After about an hour the water in the tank had a slight "rusty" color, the areas or BGA I had "painted" were a definite brown, areas of BGA that were heavy but had not been "painted" had some of the brown, and plant leaves that had a film of BGA and a film of brown. After one hour I turned the filter and airstone back on and continued to observe the fish for any signs of distress for an additional hour. After a couple of hours the water cleared and the fish become more active. After 24 hours the areas I had "shot" had turned a grey color and the BGA appeared dead.
> 
> I followed the same procedure for dosing the next day again dosing the areas with heaviest algae that was yet dead. The dosed areas bubbled and turned rusty but there was not as much bubbling and rust in other areas (I think because areas with a light coating of BGA had been killed on the first day), the water did not changed color as much, and bubbling activity and any discoloration cleared in about 2 hours.
> 
> Each day for a two week period I followed the procedure I described above. Each day the amount of BGA diminished and after about 8 days the BGA appeared to be gone. I continued the treatment for an additional four (4) days just to be sure there was no residual "hiding" in the crevasses of my driftwood or under plant leaves. It was not necessary to hit the BGA directly with the hydrogen peroxide to kill it. For example, on the edges and undersides of plant leaves I did not "paint" the areas but after about 5 days the BGA had turned rusty brown, was breaking away from the leaves, and was falling off.
> 
> As a side note I also had an outbreak of Black Brush Algae (BBA) in this same tank; probably due to the low CO2. The treatment described above worked on it as well, but the BBA did have to be "painted" to die and areas in bright light responded the best to treatment."


I hope this information helps you. Since May I have had just one situation where the BGA tried to re-establish itself (when I missed fert dosing for a few days) and I followed the above procedure (clean filter; increase fert dosing; increase water changes; treat with H2O2) and it was gone in two days.

Keep us posted as to your progress!


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## DJKronik57

Seattle_Aquarist said:


> Hi Andrew,
> I increased my fertilizer dosage to 1/8 teaspoon (tsp) of KNO3 (potassium nitrate) and 1/64 tsp of KH2PO4 (monopotassium phosphate) per 10 gallons daily.


_Wow, that's 2 tablespoons of KNO3 per day, and 1/4 tablespoon of KH2PO4 per day!! Is an overdose of nitrates going to put my fish at risk? Just worried about dumping this much into the tank, seeing as the most I've ever done before was less than a quarter of that dose._

*EDIT:* Never mind, missed the "per 10 gallon" part! Unfortunately, that's currently less than what I'm currently dosing. I'll try doing another water change during the week and cleaning out my canister filter again though. I also noticed that my BGA doesn't seem to react to H202. It bubbles, but it seems to be fine afterwards unless I manage to get the H202 under the "skin."


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## Seattle_Aquarist

Hi Andrew,

I think several things aided my success: I turned off all water circulation 5 minutes prior to dosing H2O2 and did not re-start the circulation/filtration for 30 minutes; I "shot" the H2O2 directly onto the BGA with the syringe and without the circulation the H2O2 stayed in contact with the BGA longer; and I dosed after the lights had been on for a least 2 hours to insure the BGA was at maximum photosynthesis (this is a key to success based upon articles I read on treating Cyanobacteria in sewage treatment plants). I tried the Maracyn treatment with minimal success. 

BTW, I dose the 1/8 tsp. KNO3 and 1/64th tsp KH2PO4 per 10 gallons as my daily dosing level now and have not seen any BGA for 6 weeks.


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## houseofcards

If it was my tank and the KNO3 increase didn't help I would do everything to make your water as clean (low organic) as possible. I have never met an algae or BGA that liked clean water. I would remove as much as you can with a filter hose, do a big water change, clean out your filter and add organic removal products (Purigen/carbon, the kitchen sink) anything that will remove organics from the water in tandem with less feeding, etc. Do a few more manual removal/WC during the week and see where you are.


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## Newt

BGA101:
- Polluted water - organics too high>>>water changes, find source and correct
- Dirty filter or under filtered>>>clean filter(s), increase filtration, do regular maintenance
- low nitrates>>>dose KNO3 and maintain minimum 10ppm, 20 to 30ppm even better
- very high phosphate>>>lower PO4 levels, see if anything is contributing to high levels and correct
- lighting spectrum too high in the 550nm - 600nm range or old bulbs>>>change bulbs


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## Tex Gal

I'm sorry, it is Maracyn not Maracyn II. Sounds like you have lots of good advice.


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## Newt

I forgot to provide my typical BGA warning: BGA is an hepatotoxin (liver) take caution not to splash water into mouth or eyes. Maintain good hygiene. It is better to handle affected plants with tongs and not bare hands.


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## jschall

I had a bad BGA problem. I tried doing more, bigger water changes. I tried cleaning the filters more, I tried adding kno3 (to a 75 gallon tank with 2 anubias plants in it), I tried manually removing it, and it just kept coming back.

Then I decided to try different bulbs. My previous bulbs (t8s) came with the all-glass hood, and were slightly reddish. I went out and spent something like $3 on a couple daylight tubes for office buildings.
The algae was gone, probably 3 days later.

Now, if only my BBA had disappeared with it. I'm not sure if it's still alive and spreading, but it sure is still attached to things. That stuff just will not come off.


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## James0816

Did you ever test for PO4? Might have missed it. You may need a phophate pillow.

For your nitrAtes...try to maintain a minimum of 40.

Black outs are never a good idea when dealing with this stuff. It will do more harm to your plants and usually causes it to come back more aggressively. Like ticking it off if you will. ;o)


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## virgo888

BGA is a headache. After treatment, it killed all my good bateria too. I have an green algae boom - treated with UV. BGA was gone and aka dormant. Once my water conditions got bad ( not enough nitrates) , BGA started again in the corners of the tank. Personally, I would clean out the tank and gravel and start over.


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## darkoon

some information on BGA here
http://www.theplantedtank.co.uk/algae.htm

I had same issue, I had bush algae, green spot, and BGA in my tank. I took everything out, cleaned up manually as much as i could, siphoned the substrate, re-scaped. then dosed with extra dosage of excel, that cleaned up all the algae in my tank, it's been 2 weeks now. GSA is coming back, but there is no sign (knock on the wood) of BBA and BGA so far.


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## albirdy

H202 sounds like a miracle drug. What is it exactly, and where can I get my hands on this? 

Newt, thank you for that summary. I have been having issues with BGA (cyanobacteria, correct?) ever since establishing my tank--with a brief cessation with the introduction of excel (although overdosing this killed the bga, it also killed my amano shrimp). To be honest, I knew I had to clean my filter--but have been avoiding it. And wondered which of my ferts I was over doing, or skimping on. Thanks for the insight, I will try to amend my maintenance accordingly. 

Very helpful thread.


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## killacross

^^H2O2 is hydrogen peroxide

its the clear liquid you put on cuts and it foams to disinfect

availible at any grocery store...walmart...kmart...drug store
and its dirt cheap...like $2 for a BIG bottle


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## JERP

I had the same problem. My ferts and lighting were all good, but I kept getting BGA in specific areas of the tank and not in others.

What finally worked for me is I added a very small (3W) reef water pump to increase circulation. The pump is only on during the day. My water is now much clearer, all algae went away, no mulm builds up on the bottom, and my fish are much more active. Of course the fish have to be more active if they don't want to be pushed around or pinned against a rock. 

The only downside is that I have to clean out the pump every once in awhile or things get really noisy.

Since the OP already has supplemental current, check for dead spots in the water column. If the tank is several years old and well established, try putting some carbon in the filter to remove dissolved solids.


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## DJKronik57

Alright...still battling. Here's the update:

I brought the BGA problem under control with a Maracyn treatment followed by upping Phosphate dosing along with keeping higher nitrate dosing and dosing Epsom salt for Mg as well. I did not, however, get rid of it. It just hung out and grew here and there, just very slowly. This lasted for a few months. I was just happy to have a reprieve. I noticed my plants were not doing all that well though, and tested my water.

Nitrates: 50ppm
Phosphates: 5+ppm
KH: 3 degrees
pH: 6.4 mid-light period

At this time I was dosing 1/2 tsp KNO3 every other day 3 times a week (1.5tsp per week) and 1/4 tsp KH2PO4 every other day 3 times a week (3/4tsp a week) along with 1/4tsp CSM+B and 1/4tsp Epsom salt after 50% water changes once a week.

So I figured it had to be a micro issue and was overdosing P and N, so I cut back on P and N to normal levels, or half what I had been dosing (1/4tsp KNO3, 1/8tsp KH2PO4 3 times a week). I started dosing CaSO4 and upped the dose of Epsom salt as well. I also cleaned my filter again at the same time.

Within a few days, the BGA came roaring back. Not exactly sure why.
So here's the BGA checklist:

*- Polluted water - organics too high>>>water changes, find source and correct
- Dirty filter or under filtered>>>clean filter(s), increase filtration, do regular maintenance*

I clean the filter regularly (an Eheim 2217, every 2 months or so), do 50% water changes weekly, and suck up as much mulm and debris as I can while doing the water change. The tank is not overstocked, but does have some dirty fish (1 gourami, 1 clown loach, 2 zebra loaches, 2 boesmani rainbows, 2 ottos).

*- low nitrates>>>dose KNO3 and maintain minimum 10ppm, 20 to 30ppm even better*

Regularly tested at 40-50ppm or more KNO3 before I reduced the dosing. 1/2ing the dose, I expect I'm around 20-30ppm, will test this when I get home.

*- very high phosphate>>>lower PO4 levels, see if anything is contributing to high levels and correct*

This could be it, but I was maintaining 5+ppm phosphate levels for a few months while the BGA was mostly slow growing if at all. Dropping back to normal levels seemed to cause it to grow quickly again.

*- lighting spectrum too high in the 550nm - 600nm range or old bulbs>>>change bulbs*

Bulbs were replaced at the beginning of this ordeal (about 3 months ago).

So what I'm seeing here is:

1. I'm simply not cleaning enough. Do I clean out my filter weekly? Do I do bi-weekly 50% water changes? Do I get rid of some fish?

2. My phosphate and nitrate levels are somehow out of whack. Both (when high) seemed to keep the BGA slowed down, but did not get rid of it. My plants also did not grow like gangbusters, which makes me suspect something else was limiting (like Ca or Mg). Added these, and reduced N/P dosing and got a BGA growth spurt.

I'm going to revert back to my high N/P dosing and see if I can slow this stuff down again, but any thoughts/input are welcome!


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## Newt

DJKronik57,
I'm curious if your KNO3 has a funky odor ?

Is your BGA typical. i.e. smells, comes off easily, slimy?


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## DJKronik57

Newt said:


> DJKronik57,
> I'm curious if your KNO3 has a funky odor ?
> 
> Is your BGA typical. i.e. smells, comes off easily, slimy?


Not any funky odor I can tell. It is the last of a batch though; does it go bad? Even still, it brings my nitrates up, that's for sure. Nitrates just tested around 30ppm. Dosed it yesterday.

The BGA is classic. Gooey and smelly. Comes off easily...not out of moss!


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## Newt

No, KNO3 does not go bad.
My last batch smelled really bad (and its supposed to be odorless) and I had an algae outbreak. It has ammonia in it. Not sure what algae it is but it is slimy but doesnt have any other BGA characteristics.


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## T-PHAN

Have anyone try the E.M.Erythromycin from API?
It work for me on BGA.


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## SuperWen

i will share how i treat BGA in my 10L and 3L tank:

- treat the BGA with double dose Azoo Carbon Plus (or seachem excel), i inject to the substrate and to substrate surface. in 24 hours BGA will turn to light green and die
- siphoned and manually remove the rest of died BGA
- mix 1 tablet amoxicillin (antibiotics) with a glass of water, and pour into tank
- blackout in 2-3 days
- overdose bacteri starter and aerate water for 1-2 days


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