After having BBA in the tank for almost 1 year (reading 100000 articles about it) i figured out that BBA starts to grow more and more if the plants in the aquarium are not growing well .
In my experience in all 3 tanks it is a combination where light always is the main factor.. And if light is ample and plants are not realy healthy BBA will firstly attack the unhealthy plant parts. Unhealthy plants mainly caused by nutrient insufficiencies or just older leaves dying off..
If light is more than ample BBA will even attack hardscape.
For me this theory works in every case, got a little 25 litre tank i use as plantbin.. It is super low tech, no filter nor flow, very low light less than 9 watt led light, if i have to guess maybe 700 lumen maybe less. No ferts, no foods, very low on co2.. only cramped with plants and shrimps.. Gets a weekly 50% water change. There is a lot of melting going on in this tank but never ever grows BBA, the only algae growing in this tank is diatoms.. Even if i throw in a plant from one of my other tanks containing BBA it dies off.. So if light is low enough than the TT doesn't hold ground, than bba even doesn't grow on the unhealthy parts of a plant.
So just only saying plants not growing well is not the correct approach.. For example putting a Java fern in a very bright lit tank or any other slow grower.
It grows well and maybe even relatively fast for a java, but gets to much light and there for most likely also will start grow BBA. This algae attaches deeply into the plant cells, the longer it is on it the deeper it will eat itself into it..At one point it will start feeding off the host and make it unhealthy..
So if you think of it, it is a combination of several variables.. Light, health (ferts/co2) plant sp. with different grow characteristics put together. Next to that flow can be a additional variable with distributing ferts/co2 around..
Actualy it is very simple.. If light is ample you need ample co2 and ample ferts to make the plant do something with this light.. Next to that you need plant sp. that have grow characteristics meeting these variables. For example you can not make a Java fern grow as fast as a Rotala, if you try you are just wasting ferts, co2 and light. Maybe having a nice rotala and bba on the java fern.. When it comes to the flow variable, you might take into consideration and ask the question whats wrong here... Is it the flow or is it the wrong plant sp. in the wrong place? As light and shading in a scape is an equaly important variable here.
What makes this whole subject so illusive and dificult is because we are talking variables here. There isn't a constant number to give.. Plants grow in mass, more mass can take more of everything. Lights are expressed in watts and lumen, but still it's just an illusive number not saying very much it still is different for each tank even with the same numbers given.
Keep up the ferts and co2 and play with your ligh intensity is where you need to start.. But it takes time and patience.. Lower it with 10 or 20 % or more and prolong the period if necessary and wait several weeks maybe 2 months it's a variable and impossible to give a number.. But wait and see what happens.. You will see less BBA..
😉 and probably more plantmass.
😉
If you do it right you might come to a point where BBA is gone.. From there you might have enough plantmass gathered to go up again with the lights.. And again go easy on it and wait and see.. Go up and down like that till you find your sweetspot..