TBH one of the nice things about Scapecrunch is that the information is consistent.This makes me wonder if my aquasoil is just depleated... It's about 1 year old, but the first 2 months were dark start and there were a few additional months that the filter was running but with no light and no plants. It never saw a plant load heavier than the last few photos (so fairly light/medium). I have never added fresh aquasoil or root tabs. I did use the pellets that come with Amazonia II, and they're still in good shape. Our apartment does get quite a lot of natural light, but I measure the corner where the tank lives at about 10 PAR at its brightest.
What you described also makes me question what I thought I knew about algae management, and my brain is full of somewhat conflicting information.
Regarding aquasoil, part of me seems to believe that since people keep plants in inert soils, then you should be able to treat depleated aquasoil just like an inert soil by dosing more nutrients to the water column. I know that this is wrong, but I don't have enough information to change my framework to something more accurate.
Likewise, many people have emphasized that "exceess nutrients don't cause algae" and that algae indicates something is out of balance (namely lighting, CO2, nutrient stability). In some ways this has led me to believe that nutrient levels don't really matter as long as they're stable and not crazy excessive, and that any algae problems are a result of lighting or CO2 not being correct for a particular nutrient level. Yet again, I know this is wrong. Dennis has a great article on this explaining how high nutrients are not appropriate for all tank types.
Do excess nutrients trigger algae growth in a planted tank?
Debunking the myth of 'Excess nutrients' as the principal trigger of algae growth in planted tank.www.2hraquarist.com
Yet, with such little experience, I find myself battling these innacurate mental models in trying to figure out how to address the issues in my tank.
Dennis has lot of great articles and lot of people have great articles at Scapecrunch as well, but to quickly summarize,
Stability is the key when it comes to nutrients.
You have to decide whether you are going to do EI (Water column fertilizer - Nitrate level consistently at a high level) or Lean dosing (Almost Zero nitrates in water column, but have a rich substrate either by placing root tabs or replinishing aquasoil - Dennis also calls this Zero bound system since one doses the WC the same as the plant absorption so essentially the nitrate level is always stable close Zero - this is the approach I do and you can read about this in my journal as well). You could also do a system where the nitrate is somewhere between them both where the nitrate level is stable but not very high as in EI, i do not have experience with this.
The fact that your new growth looks good tells me that things are going well and you just need to give it time. With the lean dosing growth rate is slower as the aquasoil depletes. But if you are seeing good growth but just slow i would look at this as an advantage for less maintenance.
As i mentioned before, i think you are neither doing EI or lean dosing and you are somewhere in between (with big dosing after WC) and that might be one of the issues with the nitrate stability and it might be worth checking nitrates with a different equipment. @Naturescapes_Rocco has a nice nutrient accumalator calculator that you can looks us as well to see if your nitrate level is stable.
My only other thought for you, which might be slightly off the usual advice is that focusing on getting plant mass might be more helpful at your stage rather than getting rid of algae. Meaning just let everything grow out real dense without doing too much replanting. But i do highly recommend reducing the PAR level to close to 50.
Just my 2 cents.
