[MoreliaViridis]

More plants, more organics, more nutrient and CO2 demand, less flow.
Time to trim and do some maintenance.

Reduce stem counts and replant tops. Remove unhealthy parts and all visible algae.
Give some space between bushes. It will look ugly at first but plants will fill out quickly. It will give better flow at lower levels and produce more contrast between plant groups.
As you pull out stems vacuum the substrate. Suck up all the gunk out.
Clean filter and pipework. Clean glass (Or you can leave GDA for a month and scrape it off. For some people this works wonders, for me never worked).
Do large % water change. I typically do 80+%.
See how that goes.

If issue persists after all this then we can look into ferts and stuff.
Ferts are less important then most of people think.

 

[MoreliaViridis]

Fertilizers (nutrients) are the most important part of the planted tank hobby. Regardless of where they originate (broken down fish food, fish waste, your city's water supply, substrate or dosing the water column, they're required for plants to live and grow.

Don't make claims like this without providing some explanation, as they only serve to confuse newcomers. It's important to be specific in instances like this.

I'm not saying fertilization is not important. It is.
However some people go down the rabbit hole chasing dosages and ratios thinking it is everything that they need to run a good tank.


Biological maturity of filter, good turnover rate, regular water change, no hideous stuffs in tap, good light intensity and spectrum, good CO2 concentration and distribution(some might say this falls into ferts), good gaseous exchange, good maintenance practice, proper plant handling techniques, ability to observe plant health changes....
All these things contribute to general tank health and fertilization is only one of them. It is a rather big chunk, but it is not everything.


Many experienced people does not mention these because...they are basic stuffs.
And these are basic for a reason: any high-tech/high-energy planted tank will not be as "balanced" as it can be without these. Wet elbows make tanks better.
Only after other factors are proven to be without issue, fertilization can be brought into consideration as other factors can skew or mask whatever impact ferts are having.