Like I said...ytl and overdrive seem like agreed is due to lack of NO3. so, do you think yr new tank with enough NO3? Or you just addind the old water? Or you have enough fishes or feeding to balance up the NO3.

Normally new tank is lack of NO3. cause of we up the tank and not introduce any live stock in immediately. And where is the NO3 come from? Unless you mixed with some old water. So, the old gravel which with bacteria formed.

I don't think blackout will help much. It is stop or slow down the BGA growing. But the existing BGA will remaining there. coz i tried that before. The stump removal (KNO3) is good enough to balance up the NO3 level of yr tank.

I saw some stump removal in Ikano Ace Hardware shop. Beside there, that is a hardware shop located in new wing of 1 U selling it.