Hi,
To be absolutely honest, your tank looks to me like the one which will be difficult to grow plants in long term. I can see some plants which look like Cabomba to me – am I right? They look O.K. for the moment but I am not sure they will be doing well long term. It seems to me – I might be wrong – that the substrate is hugely wasted as you have a thick layer of ADA one but only a few plants. Without plants, it may become anaerobic with time. As for the algae you showed the pictures of, it does not look like any of “common” types to me. Anyway, razor blades as Mark suggested, or even an old credit card can be tried.