Great original post with plenty of details. If you’ve tried everything and it’s not working, I highly recommend you to STOP EI DOSING. If you have light, co2 and adequate nutrients in the water but algae is growing, that means your plants aren’t making use of the light/nutrients. Something will make use of the light/nutrients – that’s algae.
Here’s what I would do if I was in your position:
– 100% Water Change.
– Remineralize water so that it’s 4-8 gH. I use equilibrium. If you are in an area with really hard water, I recommend you mixing it with RO to at least get it to 6-10 gH.
– Do not do any type of dosing, equilibrium has lots of macro nutrients (if you check the ingredients you can see what there is exactly).
– Set your light period to be 6.5 – 7 hours max.
– Let your tank do its thing for a week and see what happens.
– If you tend to feed your fish a lot, then you will need to do water changes more often (algae loves ammonia from my experience). I recommend the day after a feeding.
– If you feed every day, then I’d do a 30% WC every day with one big one at the end of the week.
How do you know when to dose? When all your plants are thriving and growing, that is a good time to start dosing again to make sure they have enough nutrients. If you use all in one ferts, you definitely should be doing a WC every 2 days IMO.