Question 1, Calcium

[steve-s]

Originally Posted by StirCrazy

nope I was thinking anything over 400ppm, now how much difference will 400 to 420 make?? I don't know it may be a mm every 6 months. I try to keep mine under 400 and 380 is the target.

Yup, that's what I meant in general, Ca should not actually exceed 420 ppm but in reality, the coral begins feeling stress (working harder?) at the 410-415 mark. Personally I keep mine between 400-410 ppm as a rule.

Let me explain something first, the Ca levels I am talking about are going to depend on your Salinity also.. there is a balance for salinity VS Ca. for example if your salinity is 1.027 then your Ca should be 415ppm for the balance, higher than this and you are in the zone of diminishing returns, if your salinity is 1.023 then you are probably looking at about 360ppm for a ballanced Ca level, so if you keep the tank at 1.025 then you might want to be aiming for about 390ppm Ca

Your in the right place, just might want to use a different designation. If keeping your water at 35 ppt, Ca should be 415 ppm. When you reduce the salinity by say 30 ppt, you've diluted the chemistry overall by 15% (30,000/35,000). Typically why some have problem maintaining target levels to begin with. So the 415 ppm would also be reduced by 15% giving you a value of 352.75 ppm. Same explaination, just different route to get there.

Cheers
Steve