Thank You gents, I Ask about this meter because it's the only one I'm familiar with. I can get one delivered for around 350 from BRS. I'm in hurry. My 75 dedicated to improve my coral keeping skills is looking sad. The variety of corals I have are bleached etc . I "think "my water is good so could be the lighting is too strong or could be too low ?? Just trying to cover all the details. Like I said I'm used to this meter but can't get my hands on it any more. Now when You guys talk about" immersion correction factor" I'm lost. I just want a meter to tell me if the lights are too strong or vice versa . Thanks