JBL The 7 + 13 balls
JBL The 7+13 Balls is a specialy formulated root fertilizer ball for long term fertilization in an established aquarium, It contains iron and a range of essential minerals in a form readily accessible to plants to absorb through there roots. Depending on the size of the plants press one or several balls into the root zone once a year. this contains no phosphates and nitrates so unlikely to foul aquarium water.
