Hani, this tank is very over grown and high very high plant biomass to say the least!

The close ups seem like pictures from a poor/low CO2 plant tank.
As plant biomass increases and becomes really high, the amount of CO2 demand goes way up also.

If more CO2 is not added, then the plants will slow(not stop) their growth, and this can lead to PO4 and or NO3 back up, rarely NH4.
Plants will start to leach PO4 and NO3 out if they are stressed from low carbon.

So you can get a spike of NO3 and assume that is what is causing the poor growth etc, rather than CO2 and providing a good trim and a stable plant biomass.

Keep the garden pruned and tidy basically and you should not have too much issue.

More plants= more nutrient/more CO2 and more light demand.
Less plants = less of these.

The algae and twisted tips look like poor CO2 in the photos.

Regards,
Tom Barr