Transition to Low-Tech: BBA Issues

[Mudminnow]

Hello all,

Over the years, I feel I've pretty well mastered algae control in my high-tech tanks, but I've always struggled with low-tech. That being said, my 150 gallon (568 Liter) is just too big to get in and trim all the time, so I've been attempting to transition it. Besides, I still have my 50 gallon high-tech tank to scratch that itch. Anyway, here are the steps I've taken over the past few months in my attempt to transition my tank:

1. Replaced any plants that wouldn't like a low-energy environment with those that would.
   • I now have various cryptocorynes, java fern, java moss, and bucephalandras.
2. Turned my lights way down.
   • I have an old SB Reef Light (about 45"/114cm)
   • The light is turned down to 5% (as low as it will go) and run for 6 hours/day.
3. Turned off my CO2.
4. I sold most of my fish.
   • The tank currently has only 8 rosy danios and 3 SEAs.
5. Drastically reduced fertilizers
   • I now only add a couple of squirts/day of APT 1 (potassium and micros)
6. Drastically reduced water changes
   • Water changes have been tapering off and I haven't done one in the last month.
   • I don't plan to do any in the near future either.

As a reward for my efforts, I'm now growing BBA. Here are some pictures:



As you can see from the pictures, the BBA is now all over my plants and rocks--so ugly. It looks patchy rather than fuzzy. I don't know if it grows this way because it's a different species or because my 3 adult SAEs eat it. (They do eat it.)

The tank has some old Controsoil in the back, but I haven't added any substrate fertilizers to it in years. The front of the tank has a few river rocks and pool filter sand.

In case it matters:

• 76° F/24 C
• Ammonia 0
• Nitrite 0
• Nitrate <20ppm (might be 0 for all I can tell--test strips not that precise)
• pH 7.5
• KH 80ppm
• GH 180ppm

Clearly, I'm doing something wrong, but I'm not sure what. Any thoughts as to what may have triggered the BBA? Is it just a waiting game at this point, or do I need to change something?

Any insight/experience welcome.

 

[Fishfur]

I could be dead wrong about this but that doesn’t look like BBA to me.

Will it brush or wipe off leaves or rocks if you try?

 

[ruud]

I'm having a hard time ID-ing as well.

Anyways, I'm seeing dark patches which brings CO2 (or drought) to mind.

To transition to low energy, I would have done everything you did except the CO2. I would have made this a very gradual process.

The other concern could be temperature, but it is a wild guess. You reduced light and CO2, but the temperature remained 76F.

 

[Zer0Fame]

Hey,

those are not BBA, but something refered to as Rhodophyta sp. 2, often mixed with diatoms and bacteria.

Your best bet for now would be a water change (even though it's annoying), as well as no fertilizer and restarting the CO2. Very low levels should be enough ... think around 4-5 ppm.

A lot of Rhodophyta are masters of biogenic decalcification. In short: They manage better than any other plant to "create" CO2. Very simplified: They create CO2 from your KH.

This leads to a precipitation of calcium, which then again the algae uses to build an armor for itself.

The "armor" is made out of lime, the same stuff that likes to collect in showers.

And CO2 dissolves that armor, introducing a weak spot in the algae's defenses.

 

[ruud]

Yup, that's it. And likely caused by the ending of CO2 gas injection. Plants are addicted to the level of CO2 they receive in the morning. If it changes, they'll seek more energy-costing ways to achieve similar levels. Typically rise in rubisco production, but some are able to utilize carbonates.

 

[BeachCruiser]

When i had that problem, i H2O2 dipped the epiphytes/hardscape, removed as much decaying organic matter as possible, reduced photo period to 6 hrs & did weekly 50% water changes. Once eradicated, i very gradually resumed fert schedule & increased lighting. It hasn't returned.

 

[Mudminnow]

Thank you all. This was very helpful. I didn't even know Rhodophyta sp. 2 was a thing until now.

If Rhodophyta sp. 2 is so good at getting carbon from KH, wouldn't I want to stop changing my water? I mean, wouldn't it be best to let the KH get depleted? My tap has high KH and GH, so I fear I'd just be replenishing what this Rhodophyta uses with any water changes.

Conversely, might it be a good idea to get some plants that are also good at getting carbon from KH? Vallisneria come to mind. Might adding some vals help fight off the Rhodophyta?

Will it brush or wipe off leaves or rocks if you try?

It will not brush or wipe off. It's very stubborn stuff.

 

[ruud]

The cause of rhodophyta is typically associated with a lack of macro minerals for plants. Your remark on nitrates, would support this line. But it simply doesn't fit with my personal and second-hand observations.

I associate red algae in general, but not exclusively, with specific plants and a change in CO2 availability, that causes plant leaves to respond with CO2 uptake from carbonates by lowering the pH on the underside of the leaf and consequently the pH on the upper side is increased (massively), forming calcium deposits, which I then spontaneously associate, based on marine environments, with red algae.

But there are obviously different hypotheses to craft. Why does it occur on plant leaves. We know it can also occur elsewhere. Is it because red algae probably distribute via plants? Are plants in stress (from the drop in CO2 levels), giving up on repellents because they put their resources on rubisco, allowing algae to set foot?

In any case, I continue to point towards CO2 injection. Many plants, including those in your tank, do just fine in very low CO2 environments of course, but it is the change that made plants to respond and trigger red algae. Hence, I would have lowered CO2 injection very gradually, instead of abruptly.

Regarding valls or KH drop. I don't have to tell you how complex, dynamic and interactive planted tanks are. It is seldomly a case of doing one thing specific that will lead to a desired outcome. You introduce valls and they might simply adjust to the current CO2 levels. You allow KH to drop, but rhodophyta might very well continue.

But CO2 is the workable exception as plants are so sensitive to its availability and stability in consecutive mornings when photosynthesis occurs. Regardless if you dropped the light intensity. Outside, light intensity fluctuates due to the weather. CO2 on the other hand is much more stable.

In general, but you already know this of course, see to it that plants are healthy. Healthy plants take care of your tank.