I will be leaving for 7 days tomorrow and have arranged for someone to come every other day to feed my fish. My 40 gallon community tank is relatively new but fully cycled with nitrates always around 5.0. I do large water changes every other day, though, as I was getting nitrite readings up until about a week ago. Should I try to have the person do a wc while I'm gone? I'm worried they won't do it correctly. Will telling them to treat the tank with prime help? Also, how many times should I have them fed to minimize high nitrates?