Time to ask for help
There really should be no need to run Caribsea ARM at pH 6.5. You should be able to get acceptable parameters in the pH 6.8-7.0 range with ARM.
Are you dosing anything that has Magnesium in it? An imbalance of magnesium can allow your Ca to climb out of range in relation to your Alk. With such a high Ca concentration your lowish Alk readings aren't really very surprising.
And I agree with Marc that Ca in excess of 400 mg/L or so really isn't necessary. Good Alk levels will help ensure your SPS get good growth rates - Marc has very impressive SPS growth rates so I'd be inclined to take his advice (which also coincides with Darren's).
I'd also look into other possible causes for your low pH. I'm sure you've done this already, but make sure your surface agitation is adequate to promote good gas exchange, and it's also possible that, with the cold weather we're having, you've had your windows closed and there may be a lack of good gas exchange in the room your tank is in, leading to higher room CO2 and lower O2 levels. Do you have a fireplace or woodstove in your house that you've been using during this cold snap?
[ 24 March 2002, 21:09: Message edited by: Canadian ]
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