Let me see if I understand the care and upkeep part of your post. Your saying I need to test for 2 things in the water with my setup - ph for chlorine and tds for solids (not sure what solids yet). The instructions on my nutrient solution will tell me how much water to add, correct? Then I just measure for the tds and ph every day and change the water when the tds reads too high? Is that about right?