I suspect you are overdoing it on this side. In my reef I only use skimmer and activated carbon (30ml per 100L that I change every 4-6 weeks). I have. No fleece, fuge, GFO etc…. When I had those or multiple of those methods I was looking at nice dead corals and lot of algae.I'm running 2 filter rollers, a skimmer, an algae scrubber, a UV and ozone.
If you started with non live rock / substrate you need to build up your biofilm. If you remove all of your PO4 and kill all the bacteria your biofilm will not function properly and algae will take over. Also I suspect your trace elements need to be adjusted, again dead rock will mess with your trace elements and scrubbers will remove what is left over.
My suggestion is to reduce your export. Consider dosing TM Plus NP or TM Bacto Ballance to build up your biofilm. This is carbon dosing not for nutrient control but to build up your bacteria/biofilm and it contains trace elements that bacteria needs. Start with 1/4 dose of what TM recommends. Other products might work but I can only comment on what I tried and what worked for me.
Try that for few weeks to a month and see if there is improvement.
Also consider to perform ICP test from reputable company (I use FM Total ICP) to figure out what your water chemistry is and what might need to be adjusted.
Good luck,