To answer your question about water changes. Large water changes performed less frequently
remove far more toxins than smaller water changes performed more frequently.
Assume a weekly nitrate accumulation of 20 ppm for each example below.
A 25% weekly WC results in 60 ppm nitrate after each WC, 80 ppm before each WC, 70 ppm average.
A 50% weekly WC results in 20 ppm nitrate after each WC, 40 ppm before each WC, 30 ppm average.
A 50% WC every 2 weeks results in 40 ppm nitrate after each WC, 80 ppm before each WC, 60 ppm average.
A 75% WC every 2 weeks results in 13 ppm nitrate after each WC, 53 ppm before each WC, 33 ppm average.
Note that 50% every 2 weeks beats out 25% once a week.
https://www.hamzasreef.com/Contents/Calculators/EffectOfWaterChanges.php