But BBA is never a nutrient issue
Ever..........you might slow the growth some, but it because you limit the plant growth via nutrient limitation thereby reducing CO2 demand.
So...........if you are limited with say K+, or Ca++, or NO3..............then adding more CO2 is not going to do anything.
Your limiting rate step is still the K+ etc........not CO2.
This can relieve some CO2 stress by using PO4, K, NO3 etc as limiting nutrient.
So you bounce between CO2 limitation and a nutrient limitation...........
It's only when you realize that providing non limiting conditions for all the nutrients, as well as CO2 do you get an algae free tank.
Everyone that fails at EI fails pretty much for the same reason and this one reason accounts for about 95% of all algae related issues: CO2.
I sound like a broken record but I've shown 100's of times that excess nutrients do not cause algae with good CO2..........the problem is that many assume they have good CO2.
Virtually every method to measure CO2 under shoots the ppm.
So they think they are fine there.
Or they have a method that they over shoot and gas their fish, then they are gun shy and never add enough thereafter..............
You should always adjust CO2 SLOWLY and carefully.
Plants are the gauge.
R macrandra is CO2 sensitive and will stunt like this with poor CO2, I've seen this perhaps 100 times over the decades.........I've never seen it stunt due to high PO4, NO3, fish loads, sediment types, high K+, high Fe/Traces etc etc.....
Ever............
I have seen it many times with CO2 however.
Many think they are doing great but really have not mastered CO2 fully.
When they limit PO4 or reduce their nutrients way down in effort to try something else, they happen upon secondary reduction oif CO2 demand and assuem that it's better to have limiting nutrients.
Too strong of a limitation, then they get algae and stunting............
You can grow and balance things that way, but until you have full mastery and control of CO2, you cannot suggest that limitation is the reason for algae control, you have confounding factors such as nutrient limitation which down regulates CO2 demand.
The test and data are not independent, they are dependent...........that makes figuring any thing out very difficult if not impossible and leads folks to make erronous conclusions.
Only by providing non limiting conditions for every thing except the nutrient of interest, can you fully test.
Be careful with CO2, figure out a way to add it faster and better to your tank, that is a very worth while endeavo for your tank/hobby etc, more than any other.
Regards,
Tom Barr