My tank also has Pukani from BRS, I acid washed and pressure washed my rocks as well. The only bad thing about pukani is it leaches tons of phosphates for the first 6-8 months of it being in the tank.
In hind sight I should have cured the rock in a barrel first but the reality is I didn't so the phosphates just leached into my DT, the rocks were clean for the first 2-3 months like you had and then boom green algae.
I'm glad to hear that the lawnmower blenny is starting to get the algae under control.
I just wanted to let you know that I guarantee that the rock is most likely feeding the algae