I have been changing my water reservoir nutrient solution every week and filling it up every other day. however my closet is very crowded with the two deep water culture buckets they are getting difficult to change do I have to change the nutrient solution every week or can I just keep filling it up. There only 4 gallon buckets so every day i add at least a gallon of nutrient solution. I only have 2 weeks left and whats a good ppm for the nutes? 50 day old auto?