Salinity Problems

So I followed the directions for Instant Ocean yesterday: 1/2 cup per US gallon.  The tank is 30 gallons so I added 15 cups.  This morning I went to check my handy work.

The temperature is 78 degrees, a little lower than I want but I can bump that up.  And holy cow!  The salinity is off the chart! 

I'm glad I didn't need this water right away for livestock, it wouldn't have worked.

I took some water out with a bucket, added more tap water and added more Prime.  Then I checked again.  Still too high.  I pumped out about a third of the water (maybe 8 gallons) and refilled with tap water.  Dosed with Prime again and tested the water.  Now it's too low.  At least the swing arm is bouncing into the green area.  I've added another cup of salt this evening.  I'll let it mix awhile and see where I end up.  Hopefully, by the end of the evening, I'll be where I want to be.