Looking for some input/help; my tank is suffering a big GHA & Cyano issue

[gregzz4]

Bought a new NO2/NO3 kit tonight and will check tomorrow

Did a 3-day blackout over the weekend. Nothing suffered much and the GHA backed off enough for me to get a bit of a grip on it. Plus the cyano and diatoms have subsided ... for now

Tonight I siphoned/scrubbed off as much GHA as I could and then added a Sea Hare
The little Bunny is going to town like there's no tomorrow ... each section it passes over is scoured right down to the LR

So, now all I have to do is figure out where this problem came from in the first place ....