I don't have BBA at all.
That sounds pretty arrogant, but it's the truth.
The reason I don't have it is because I've addressed the source of the cause of it: excessive micro nutrients.
It's got nothing to do with organics and everything to do with your water parameters. Hence for a quick summary of WHAT and HOW MUCH elements are in your water just do an ICP test.
They cost money but then you KNOW what's going on, instead of guessing or having endless discussions about this and that but not pinning down any values or specifics.
They may well be reputable but these things get passed along supply chains. As long as we pretend that any algae can show up in any tank, we do not demand that the suppliers be better. We deal with algae so much in this hobby, we need to get a better handle on its biology.
That's why I decided to use only invitro plants, no pests or any other nasties that might come with it. Also no snails too.
In terms of control, there are good methods using hydrogen peroxide out there (these algae species are susceptible to that while many others are not). And some people have had success with Seachem Flourish Excel (I believe). However, it's a bit of a nasty chemical in my mind, so I've avoided using it personally. Perhaps somneone with experience with it can weigh in so you can consider it as an option with more confidence.
I agree with the other posters. Don't use Excel, it's horrible stuff. Hydrogen peroxide should be OK since it's not really toxic.
Brush algae needs light and nutrients. In tanks with live plants, the goal is to find the balance of light (intensity and spectrum and duration all factor in) and available nutrients so the plants benefit but not the algae. Too much light (intensity, wrong spectrum, on for too long or not long enough sometimes) has been the most common cause in my experience, but I have a few times found it suddenly increase if I increase the plant fertilizer, obviously beyond what the plants can use first. I have had it begin to increase when the tank lighting has weakened and needs replacing. I used to have it increase every summer due to the increased daylight (intensity and duration) entering through the windows; having a dedicated fish room, heavy drapes blocking most of the light ended the summer increase of brush algae.
You've verified my suspicions. But it depends on what fertiliser, macro fertilisers no, micro fertilisers yes, but with All-in-One fertilisers increasing the dosage increases the micros too.
Again your reply is vague, but I don't blame you. It's very hard to discuss the quantities involved sometimes and what's causing the mischief.
I agree that too much light can cause algae - if your dosing is wrong for that level of light. Light probably acts as a magnifying glass on your dosing errors. More light and the bigger your errors will show up. You can get away with some careless dosing on low light. I run about 12 hours daily on high intensity and in the process of trouble shooting the remaining algae issues at the moment. BBA and BGA algae are not on that list since I don't give them a chance to even grow.
My experience with Black Beard Algae was that it was caused by organic buildup in my substrate. At the time the tank had a thick carpet of plants that covered about 75% of the substrate. This made it very hard to do a though vacuum of the substrate. And a google search brought up comments that organic buildup could cause it. I also wanted to replace the substrate with black diamond blasting sand.
Not true.
My tank is heavily stocked and the fish produce a horrendous amount of waste. Even though I'm running 3 times tank volume turn over a significant amount of fish waste and organics collect on the mosses and the large Blyxa Japonica bushes I have. It's so bad I have to get a net there from time to time to stir it up and collect it.
I would suspect that your substrate had a CEC capacity. It's absorbing a lot of the nutrient dosing you put in and then leaches it out. If you dose excess like the EI (Estimative Index) method then you'll literally be poisoning your tank - this is why those who run it have to change their water EVERY week.
The most damaging and idiotic concepts promoted in this hobby was the idea that excess nutrients don't cause algae. They damn well do. The idiots who are promoting it also promote:
1) 30 mg/l of CO2 as a level to aim for (green on drop checker).
If your nutrient dosing is optimal you only need 9 mg/l. Most fish DO NOT like 30 mg/l of CO2, they gasp and breathe more rapidly. I'm sure I'm not the only one noticing that in the videos of these so called planted tank experts. It's really laughable that so many people have not called them out on this.
2) no need for water testing, because excess nutrients won't cause problems so testing becomes pointless, just make sure you always have excess.
This is the most retarded advice ever offered and you can thank those "planted tank gurus" (or morons as I like to call them) for causing all this grief we see here. By not testing you don't get a handle on the problem, you might as well be shooting in the dark, or flitter from one "expert's" advice to another "expert".
3) obsession with excess flow or low CO2.
This has always been the standard stupid response. They tell you that BBA is caused by low CO2 or lack of flow - never for a minute troubling to look at the other areas like water parameters, since their belief is that excess does not cause issues we don't need to worry about it.
So here we are, discussing BBA which, for those in the know, don't have. You have to thank the youtube influencers and other idiots for promoting nonsense in the hobby and it will take some time to correct this. Meanwhile the myths will abound and we'll see more and more discussions in the algae forums.