I found this to be very interesting for anyone that's growing tomatoes or lettuce. I put in my numbers for the tomato plants I'm growing and it says I should increase my
nutrient levels but everything else was perfect. Check it out for yourself. Just put in your numbers and see what it says. Would like to hear what everyone thinks about it after seeing what it says. Here's the site.
Interactive Tomato Model - Ohio State University Hydroponic Crop Program