In terms of hair algae I had the same problems when using zeovit and products similar to zeovit.
My hair algae went nuts in my sump. Not sure of the cause but I had very low PO4 and it was still growing,
If you are over feeding the fish they will be producing more waste like ammonium and this is getting used by the hair algae.
What are the colours of the acropora looking like since the hair algae is growing??
What type of skimmer are you using ? as to get good results when using zeovit you have to have a good skimmer so it can remove the waste fast enough.
Got a friend, who is doing ammonium chloride to increase his nitrates as they are zero,
The results have been surprising as the caulerpa algae is going nuts and is a very nice green and the coralline algae which was sort of faded red is a beautiful red colour,
So I would say that the algaes are using the ammonium like fertiliser .
Will try and use some this week to see the results on my tank as I need to increase my nitrates.