I tried to watch that video on my phone last night and it wouldn't play - said the video contains content from WMG (Warner Music Group) and is restricted from playback on certain sites. I had to play it on my PC and crank the sound to hear the radio in the background, apparently Big Brother is scanning YouTube videos for copyrighted content. Wow.
Finally terminated this. Nitrate at rock bottom zero, P risen to 2ppm. So naturally thought, ahh - Nitrate limited. Then thought about it for a while, tested ammonia, and it was reading 2ppm its obviously not working for whatever reason, lack of competition perhaps?
Nothing to nitrify the ammonia? Maybe adding a little bit of live rock or denitrate would have helped?
Algae use ammonia as a nitrogen source (in place of nitrate), but it's totally failed in this case, with N (ammonia) and P rising.