Airstone is useless, ditch it. Sorry. The noise and bubbles may be irritating to the clown.
Those water readings are not good. As I said, unless your room gets cold, then turn off the heater. Better to have the temp at 75 then jumping from 75 to 85 every day. Just turn off the heater.
I'm going to suggest to take that rock out, hopefully that is causing some of your cycle problem and it will stabilize. Take it out a smell it. If it is smelly, then remove it, if not, then its your call.
Now, do you have water for a water change? Did you get the glass hydrometer? Can you do a water change and maintain current salinity levels, not dropping it or raising it? Did you add a cup or 2 of sand from your main tank?