i just purchased a cal aqua orcle drop checker off of greenleafaquariums.com, only one problem, in the directions it says to fill it by removing the rubber peice and fill the chamber, is that how all dropcheckers are filled or do you just fill it thorugh the "mouth" or whatever it is called. :help:
here is a link to the product, http://www.greenleafaquariums.com/co2-drop-checkers/oracle-drop-checker.html
