I went on vacation for a week this past January. I was worried about how to care for my high light/pressurized CO2/EI dosed tank while I was gone. After doing a ton of research and reading others testimonies I learned this was the best plan of action:
1. Do a 50% water change the night before you leave.
2. Dose your entire weekly regime before leaving, but dose your micros and macros separately. I did this by dosing the micros immediately after the water change, and then the macros the morning of my departure.
3. Cut back your photoperiod. I have a photoperiod of 8 hours, so I cut mine down to 5 hours for when I was away.
4. Adjust the duration of CO2 injection accordingly. You don't want to gas any of your livestock.
Another important thing is to adjust your timers and test them before you leave. I did this a few days before I left and am glad I did. It turned out one of my timers was malfunctioning. I was able to replace and test a new before I left.
I was nervous to see what condition the tank would be in when I returned. I was shocked to find it was in immaculate condition with a ton of healthy new growth. I did a 50% water change and the next day adjusted back to my regular regime. This method has been done by others with positive results. I'll be following it the next time I'm out of town. It was great to learn these beautiful but sensitive, maintainence demanding tanks we spend so much time on can be sustained without our guidance if proper planning is taken.