[Reefmaster]

well actually mark, i made the mistake of leaving the book on the coffee table in front of the tank on the page about pH and when i got home, the fish were all laying on their sides on the bottom and the corals were all sliming. not sure which one of the little buggers has been taking reading lessons!
thanks though. things do look great so will keep playing with it a little at a time. its a digital pH probe i'm using and have checked the calibration recently too.