Planted Tank VIP
Join Date: Jul 2002
Location: Winston-Salem, NC
Lanstar mentioned a good possibility, but another is depleted Nitrates. If your system is depositing a certain amount of phosphates into the water stream continually, but the plants are using them, then you wouldn't notice, for a long time. If the plants stopped growing because they used up their source of Nitrogen, and not enough is being replaced by fish wastes, decay, etc. then the plants will stop growing and the phosphate can accumulate.
Do you have a fresh Nitrate test kit?
- Sam P -
plantedtanker in limbo - all tanks currently in storage