Welcome to our forum.
Every time I do a water change, I too have a slight tint of green water. I balance my water etc,and within 2 days,it's sparkling clear. I have little clue as to what would cause the green water hue. I do know,that using various amounts of "lead" in glass,will give you lighter/darker green glass,dependant on the amount of lead in the glass.Just sharing my experience with ya. Chemical wise........Calcium Hardness,190-230 ALk,90-120 PH,7.4-7.6 I use a Nature2 cartridge within my filter,and dose Di-chlor after water change,4-5 teaspoons,and after each use,2-3 teaspoons. Bout every 7-10 days, I shock the spa. Every 6 weeks I change the filter. 4-6 monthes I replace the Nature 2 cartridge.GL with it,and if you figure out what and why causes the greenish hue,please share with us all.
If it is organic you can usually cure it with a good shock and let the spa breath an hour or so...