Oh and my favorite topic, while I am in the mood typing. Zero levels! I was just reading somewhere else about a guy having problems with his corals degrading and why that is happening though he has the perfect water values. All zero, can't even trace Phosphate with several test kits.
Well, Phosphate will cause algae to grow, right? So, what do you think the symbiotic algae in your corals need? Phosphate, I assume ;-) and what will happen if your Phosphate level is down to zero according to your test kit or if you us a phosphate absorbing media really hardcore?
In natural marine water you have a level of phosphate about 0,06 down to 0,015 in reefs. That level is still sufficient for the symbiotic algaes in corals, but too low for e. g. hair algae.