Old tank syndrome where the rocks and sand start releasing their bound up Phosphate has also been cured by using Foz Down.
I recently took over maintenance on a 240 gallon system with large fish that had been heavily fed for over 5 years. The Phosphate read 1.41mg/l on a Lamotte Smart 2 Colorimeter. After 2 weeks the Phosphate is now under control with the routine addition of small amounts of Foz Down via Profilux doser. The cost to do this was about $75 in Foz Down and 4 x 15% water changes. Time to start putting the SPS in.
