ADA Power Sand Advance Size:S - 2L they definitely need to be

they definitely need to be replaced

This in turn leads to an enormous oxygen consumption by the bacteria (nitrification) and to the release of the nutrients nitrate and phosphate

350 mg/L (ppm)

consider adding BioViv HUFA

Size: 265×215×198mm

ADA Power Sand Advance Size:S - 2L they definitely need to bePower Sand Special will be switched to POWER SAND ADVANCE. This product has more nutrients than POWER SAND BASIC, and on top of Bacter 100 and Clear Super, it contains BC powder (bamboo charcoal powder), which helps encourage the growth of plants. Choose an appropriate granule size (Small, Medium, Large) based on depth of aquarium water in your tank. 2 liter and 6 liter bags are available.