Half Bleached Hammer Head

[BubbleAlgaeFarmer]

Why might a head on a hammer suddenly bleach part way? I’m nervous of further deterioration and BJD setting in. I don’t want to lose the other heads in the colony. Any suggestions?

 

[revhtree Verified Admin]

Is that on the underside? Also are you sure it was sudden?

 

[BubbleAlgaeFarmer]

It is on the underside. This head definitely gets less light than the others. I've debated cutting it off and regluing it in a spot where it could get more light. This head has always seemed a tad unhappy while all the other heads are fine. The bleaching has happened with the last few days. It is worth noting that i did have an increase in nitrates recently. Did a waterchange yesterday and plan to do another in a few days.