1. I run dry nutrient salts from Chem-Gro.
www.hydrogardens.com
I use their 5-11-26 plus micros hydroponic mix, calcium nitrate and epsom salt, the last sourced from Wal-Mart in the pharmacy section because it's cheaper there lol
Veg is a ratio of 5 parts mix, 4 parts calcium nitrate and 2 parts epsom salt. pH 5.8-6.3, EC 1.7-2.0
Bloom is a ratio of 3-2-1, and I'll add approximately 1g/gallon of MKP (monopotassium phosphate, 0-52-32) somewhere around week 3 of flower. pH and EC similar to veg
2. Yes, I use a chiller but mine is bigger and used for cooling RDWC water and for water cooled air handlers for climate control. These also remove excess moisture from grow room air. Unfortunately, the fucking thing is broken so I'm winging it through the winter and hoping I can find someone who can fix it before it gets hot again. Because the same unit runs both air and water cooling, I'm reducing overall complexity and chillers are a bit more efficient than AC, especially here where altitude is high and humidity is very low. More on this later.
3. Neither! As long as the RDWC water sees a temperature of 69 or less at least once a day, it takes care of itself. I've even deliberately poured nasty rotten root water into the system while in the midst of a run and nothing happened. Proper circulation, aeration and churning action to break surface tension is all that's required for good water quality.
Please tell me more about how that inline filter sprayed water? I find that bit fascinating!