I'll throw in that's its just fine not to have a meter.....right up until you run into your first problem. Then the amount of time wasted (and money spent) to try and fix it will have you buying stuff in a hurry as you watch you plants march downhill and then having to play constant defense to nurse them back. In the meantime you've wasted time, money, and the health of your plants. And why? To save a few bucks? Doesn't make sense to me I'm afraid.