On a regular basis, you can usually do double the doses recommended by the fertilizer companies, e.g.; Seachem Excel. The API CO2 Booster, as I recall, is similar. If you have just begun the dosing, stay with the recommended dosing until you find the sweet spot for your plant growth. However, as far as algaecide capability is concerned, these only impede or kill hair-type algae. What I think I see is mostly GDA, maybe some hair near the top. Your water seems hazy. Is that just the photo? I don't see a filter.
You said you have a heavy bio-load, but I don’t see any fish (is that a fin at the top). Without the bio-load, you likely need to also add NO3 and PO4, as Flourish Comp doesn’t have much. Your root tabs will have some but, if you wish, you can eliminate root tabs in favor of water column dosing only.
You may want to get some test kits, since you are getting serious about plants. I would suggest the Salifert Nitrate, Salifert PO4, and API GH/KH kits as a start. It is important to develop a feel for the macro (NO3, PO4 and K) loadings.
Your light is good at 6 hours. You can start increasing it when you are satisfied with your tank. With any increase in light, you can then start increasing the API CO2 Booster and, you may then find that other ferts will need to go up (watch your test kits).
Incidentally, since you aren’t injecting CO2, you don’t need a drop checker. DC’s are indicators for larger CO2 levels than what will dissolve into your water from the atmosphere (max of 3ppm).