It came with a tds meter and small ph tester and ph up and down....So every two weeks you change the water and nutes right? Empty old water w/ nutes in it and fill up new water and add nutes again? This tub isn't as big as the big caddy one so I would like to test nute level somewhere besides my bathtub. Maybe another small res? They tell you at sunlight to add no nutes up to 2 inches tall. 3-6 inches 300-500 ppm...7-15 inches 600-1000 ppm over 16 1200-1500 ppm. I have checked out urban grower, good stuff