if you want my advice, drop your temps as was said to at least around 28C during lights on, lights off no lower than 17-18C if possible. that should help your leaves stay a bit more green.
now for your dwc system, if you are in a small reservoir you will see greater ph swings, and temperature swings. i prefer to use about 80 liters of water in my res, you do not need RO water, your water should be fine, and you wont need to supplement with cal-mag if you change your water out every 7 days. keep your temps in your res between 16C and 20C, no higher at all or you will risk pathogens, you will probably want to get a cheap aquarium thermometer with a probe you can leave submerged. if you do what i do, and use a beer cooler for your res, your temp issues at the root zone would be minimal, and you would be able to just throw a 3/4 full bottle of frozen water in it, once ever few days depending on where your air pumps draw their air from. i have designed my reservoirs to allow me to quickly pump water in and out by leaving a submersible pump attatched to the floor of the reservoir. this allows me to pump my water out, check the ph/ppm and make adjustments. i also use a submersible pump in the mixing tank for the purpose of pumping the water back into the reservoir, and also mixing my solution to make the whole process faster. i use a 1/2" barb to connect my hoses when i need to pump it in and out of the res. i use a 120 liter cooler for a reservoir, and i fill it with 80 liters. i basically make a mark on the side of my large mixing tote, which i think is around a 160 liter tub, so that way i can just fill it and not have to measure with buckets or anything. taking notes on how much of what solutions you use can help you quickly nute your water week after week. i ph up with tap water sometimes, but if im trying to keep my ppm in a range i will ph up with up solution. dwc is very easy, but you have to keep everything within their tolerances. if you have any questions, feel free to PM me. the best thing i ever did was start using coolers for my reservoir at the suggestion of bb57...
