This is a multi-faceted issue. First is what you mean by "green algae." Is this the common algae that lives on most every submersed surface, or some type of "problem" algae? And the "tests" that were normal, which are they and what are the numbers?
Intensity and spectrum and duration all factor in to lighting/algae. If you have live plants, then you need light that is of sufficient intensity to drive photosynthesis, and this varies depending upon the plant species. Low-light plants which are slower growing require less intense light than do fast-growing/high light species. But at the same time, the spectrum is important because only red and blue light drives photosynthesis, and red is the more important. So the light has to be of a fairly specific spectrum and intensity taken together.
Duration then enters the picture. If the light is of sufficient intensity/spectrum, plants will be able to utilize it provided that all the required 17 nutrients are also available in sufficient levels. Algae will be disadvantaged. But if any of the nutrients should become exhausted, photosynthesis slows and may even cease, depending upon the specifics. If the light remains on past this point, then algae has a real advantage as it is much less fussy over nutrients or light.
OK, two things. First, do you know any data about this light (can you provide a link perhaps)? From what you've posted I am inclined to think the light is either too intense or on for too long. Second, are you using any plant additives/fertilizers, and if so, which and how much?
While waiting for that...algae like this is normal and to be expected (the species I mean). Sufficient plant growth, not overloading the fish load or overfeeding, good maintenance (water changes, filter cleanings) and keeping the duration of the light in check can all factor in. Algae will readily appear on the tank glass, that is normal as the bio-film that grows on all surfaces provides a good home. I use a sponge scraper at every weekly water change to clean the inside of the front glass (other sides are up to you) even if I don't see any (and i never do, because of this preventative). However, too much light can thwart such prevention too.
To me those plants look like they are getting too much light (but I am no expert). Try turning down the intensity as 7 hours is not too long.
Am I right in thinking the tank is relatively new. The brown algae on the algae scraper is fairly normal in new setups and should disappear within a few weeks. It is also fairly easy to wipe off. If so it could be that your plants are still adapting to their new environment.
I concur. From the linked data [though I say it with the caveat that my experience/knowledge of LED is minimal], the light would appear to be good as far as spectrum. If you can lessen the intensity, try that. Floating plants also benefit, first by reducing light which not only works against algae but makes the fish happier (they do not like bright overhead light), being fast growers they also use more nutrients and are good for water quality.
You might look into some plant additives. Eco-complete so far as I know has little if any benefit. Seachem's Flourite is the same. When I had the latter, I still had to use substrate tabs for the swords and liquid for the floaters, no different from my other tanks with play sand.
I agree, looks like a newly established tank with transitionary algae as system gets established.
It is better, in that case, to lower light duration-- especially with the lower light plants that you have in tank.
Are you dosing water column with liquid ferts or have root tabs around plants in substrate?
This is low light Back to black. (at least the right hand side of the tank is)
As mentioned in the post the amazon swords in the middle of the tank look like they are going a bit like yours so I am moving them to the dark side () when I do today's water change. These lights are on 9 1/2 hours per day. They are at full intensity but I have gone the "filter light from the top route".
As to your question about algae your other post re feeding has a big impact on this. Change at least 50% of your water weekly and only feed what your fish will eat in 30 seconds. This particuar tank gets a 75 - 80% change every week.
50% water change wk, I've never gone that much, always wondering about shock to my fish, I did a 30% and forgot the Prime, lost every fish...that was a community tank, now I have cichlids..I think I'll check my fill water today, have checked before for phosphate. My community is always messing with the water here in Florida. Nice natural tank you have...Thank you