I use Tropica Aquarium Soil Powder (have also used their Growth Substrate) & Tropica fertilizers - as a company they've proven their soundness (they extensively test all products before release to market)
Recently I saw that Jurijs mit JS opened Tropica Nutrition Capsules & sprinkled this over the tank bottom - I'll try that on my next scape (very soft water so it's intuitively tempting 😉)
Not sure about your query re the Python ... I just do frequent 50% water changes the first couple weeks with no substrate vacuuming so as not to disturb the rooting plants
I'm lazy & run Eheims & rarely open the filter to clean filter pads, sponges etc - as I seldom observe significant algae, I continue with this (lack of effort)
I also run my filters with fine filter floss, coarse sponge, & whatever media Eheim has seen fit to include in the kit
I use intank CO2 diffusers & heaters so I'm not concerned about flow loss over media
I'd use an inline heater IF there was a 100 - 150 watt version available but over the years, these heaters have disappeared from the market rather than proliferated (too many failures I suspect - re massive tank over-heating & DOA livestock - I keep seldom available fish so not keen on tempting fate)