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Discussion Starter · #1 ·
Is the treatment for BGA any different in a lightly planted tank? I know that plants can help stabilize the tank and inhibit algal germination.

My tank has been up and running for about 3 months. It's a South American black water habitat tank, so it has only a few plants. Currently: ~12 Cabomba stems, one small Amazon sword, and a large surface patch of Salvinia.

Specs:
55g, MTS with river sand cap, 2XT5NO 20" from substrate, aquaclear 70, pH 6.8, NO3 0, photoperiod 10 hours, lightly stocked. Main feature is a huge driftwood stump.

I have a BGA outbreak on the areas of driftwood nearest the light (including directly under the filter outflow).

I know from reading many threads here that low NO3 levels can trigger BGA. My tank has 0 ppm without dosing.

Remember that this tank is pretty lightly planted. What should I do?
 

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Your setup sounds pretty similar to what I had/have.

I was lightly planted, and had some algae problems, not a terrible bloom, but it was growing. I gradually added plants, and the ones that I already had in there got more acclimated, and the algae got better. In the process I also added shrimp, so the cleanup got better, too.

My feeling on it is that things will get better if you plant a bit more, and just give it time. In the mean time, a fast-growing floating plant will tide you over...

Other people may have a different take it it....
 

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Discussion Starter · #5 ·
Thanks for all your suggestions! I've decided to replant all my Cabomba trimmings to increase plant biomass and decrease the photoperiod to 7 hours. I'm dosing KNO3 to 5-8 ppm. I also added a spare Aquaclear 30 to try to increase biological filtration and water movement.

It's not a big outbreak of BGA, but it's noticeable. About 1/3 of the Salvinia roots have BGA. There are also two patches on the driftwood, each a little smaller than a pack of playing cards.

I don't want to nuke the BGA with antibiotics unless I absolutely have to. I've read too many posts suggesting that the root cause needs to be addressed (e.g. Tom Barr).

It's going to be a balancing act; I don't want to ruin the authenticity of the habitat type by having too many plants, but I really don't want BGA. So I'll add a few more plants, try to keep them well-fed, and hope that they stabilize the tank and eat all the free NH4+.

Eventually I may have to move to a canister filter, but that's currently outside of my price range. Maybe craigslist...
 

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Discussion Starter · #6 ·
After doing a lot of research here I've learned the following: (Please correct me if I'm wrong)

The root causes of BGA in my tank
- Low to no NO3 caused plant growth to stop (limitation hypothesis)
- Then a limited number of plants meant that they weren't adding biomass quickly enough to outcompete the BGA, even with dosing.
- I may have had insufficient flow (although the BGA was restricted to the tops of the driftwood near the filter outflows)

The plan of action
- Tomorrow I'll clean filters and substrate, trim plants, and remove any visible BGA.
- 50% WC followed by...
- 3 day blackout.
- plant extra Cabomba stems in the substrate
- staple Java moss and narrow chain sword to the top of the driftwood and let them grow emersed, as well as add my new Red Root Floater (aerial advantage hypothesis)
- Thereafter I'll maintain KNO3 and KH2PO4 at appropriate levels as measured against reference solutions. Hopefully I will be able to establish a rhythm and eventually rely less upon tests.
- I will do WC less often in keeping with the low-tech ethos.

That being said; should I use the erythromycin I just bought, or sit on it for a rainy day?
 

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I have had BGA in my tank twice in the last 4 years and treated with Maracyn both times and it disappeared a few days later. Many things I read said that low NO3 was the cause of BGA but the more I read up on BGA I was begining to think that the low NO3 is more of an effect of the BGA rather than the cause. BGA eats up all the NO3 and outcompetes the plants.
 

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I have had BGA in my tank twice in the last 4 years and treated with Maracyn both times and it disappeared a few days later. Many things I read said that low NO3 was the cause of BGA but the more I read up on BGA I was begining to think that the low NO3 is more of an effect of the BGA rather than the cause. BGA eats up all the NO3 and outcompetes the plants.
Yes sir, that is correct. The most common thing to cause BGA to get a foothold in your tank is having an Anaerobic spot somewhere in your substrate. This happens a lot in lightly planted tanks since you have fewer roots aerating the soil for you.

There are lots of causes/fixes. Reduce the depth of your substrate, use an under gravel filter, plant more rooting plants, add an airstone, get a cleanup crew that will sift the substarte (trumpet snails, cories or shrimp)

However by you description it might not be BGA. How recently did you add your driftwood? If it was added in the last 3 months it is probably just driftwood algae and will disappear on its own, if it bothers you Otos and Amano shrimp love it.
 

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Discussion Starter · #9 ·
I have had BGA in my tank twice in the last 4 years and treated with Maracyn both times and it disappeared a few days later. Many things I read said that low NO3 was the cause of BGA but the more I read up on BGA I was begining to think that the low NO3 is more of an effect of the BGA rather than the cause. BGA eats up all the NO3 and outcompetes the plants.
It seems like both may be true. When plants are NO3 limited, they stop growing. BGA are able to fix atmospheric N2, thus they are able to utilize the other macronutrients even in the absence of bioavailable N. Once BGA has a foothold it may then outcompete the plants and suck up NO3. The latter is why I've determined to treat it aggressively.

Yes sir, that is correct. The most common thing to cause BGA to get a foothold in your tank is having an Anaerobic spot somewhere in your substrate. This happens a lot in lightly planted tanks since you have fewer roots aerating the soil for you.

There are lots of causes/fixes. Reduce the depth of your substrate, use an under gravel filter, plant more rooting plants, add an airstone, get a cleanup crew that will sift the substarte (trumpet snails, cories or shrimp)

However by you description it might not be BGA. How recently did you add your driftwood? If it was added in the last 3 months it is probably just driftwood algae and will disappear on its own, if it bothers you Otos and Amano shrimp love it.
It's definitely BGA. My tank is pretty low light: 2 X T5NO over a 55 gallon. Also, due to the large pieces of driftwood there is quite a bit of tannin in the water column.

Here's the link: http://www.plantedtank.net/forums/low-tech-forum/145836-first-planted-tank-upper-rio-*****.html

So there has never been BGA on or near the substrate, most likely due to really low light. It grows along the top of the driftwood, especially near the filter outflow. It is a bright, dark green mat, and has a characteristic smell (BGA). I also have a little bit of hair algae on the driftwood in other places, but my ottos, rubberlip pleco, and ghost shrimp enjoy it so I won't address it directly. I also have an MTS population keeping the substrate aerated.
 

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I'd poke your substrate with some chopsticks to look for any leaking gas bubbles to see if it went anaerobic anywhere. Even with MTS they will avoid an area in your substrate that is already dead. If that isn't the case adding a small airstone and improving flow should prevent it from coming back.
 

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Your setup sounds pretty similar to what I had/have.

I was lightly planted, and had some algae problems, not a terrible bloom, but it was growing. I gradually added plants, and the ones that I already had in there got more acclimated, and the algae got better. In the process I also added shrimp, so the cleanup got better, too.

My feeling on it is that things will get better if you plant a bit more, and just give it time. In the mean time, a fast-growing floating plant will tide you over...

Other people may have a different take it it....
BGA, which isn't even an algae, will hardly be avoided by having other plants that use up nutrients. I don't think adding extra plants is going to help. Use anti biotics, erythromycin almost always works.

Yes sir, that is correct. The most common thing to cause BGA to get a foothold in your tank is having an Anaerobic spot somewhere in your substrate. This happens a lot in lightly planted tanks since you have fewer roots aerating the soil for you.

There are lots of causes/fixes. Reduce the depth of your substrate, use an under gravel filter, plant more rooting plants, add an airstone, get a cleanup crew that will sift the substarte (trumpet snails, cories or shrimp)

However by you description it might not be BGA. How recently did you add your driftwood? If it was added in the last 3 months it is probably just driftwood algae and will disappear on its own, if it bothers you Otos and Amano shrimp love it.

I don't believe anaerobic spots are in any way correlated to BGA as I would think BGA gives off oxygen through its own photosynthesis and that would inhibit anaerobic bacteria from developing. Don't really know for sure, but that seems to be logical to me...
Work on keeping good flow as stagnant water is thought to be a cause. This stagnant water isn't anaerobic
 
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