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					Originally Posted by untamed  Looking the picture...is it possible that the large fitting on the top is a spot to insert a pH probe?  It looks too large to be JG fitting.  It looks like a probe holder/fitting to me. | 
	
 OOOHHHH!  yah know what...you very well may be right about that.  one does fit in there quite perfectly.  is that an option on Ca reactors usually?  it's seems to be a compression type fitting, the more i tighten the nut on top, the more it cinches up on whatever is stuck into it!  what do ya think?