Nutrient usage mix ratios

A question from a fellow grower:

I also have a question about usage.

I’m growing in a sealed room, 10 plants at a time with CO2, air conditioning (75*), dehumidifier (60%), 5 G8 900w LEDs with 10 additional 90 watt reds, Pro mix dirt and 7 gallon cloth pots.

Just when I start to flower the plants are using about 1 1/2 gallons every 2 days each, so using that much water, your mix ratios don’t seem to work out for me. They’re pretty thirsty.

I’ve been using Advanced and have been cutting their ratios in half, any idea where to start with yours?