Notes on Phosphorus Deficiency in Plants:
- Reddish or purple leaves and joints. Leaf tips can have brown or black spots if they are older. There will also be reduced growth, fruit or seed production.
- If pH is around 6.5, the phosphorus in the water will be available to the plants. Bone, Greensand, crickets.
- Phosphorus is toxic to fish, so you should not add large quantities to an aquaponics system. PH affects how the plants can absorb phosphorus.
- Beware of heavy metals being added to a closed loop system. Many of the commercial fertilizers might contain other chemicals that will ruin an aquaponics system.