I'm running the same size tent myself, and I could see it being difficult to keep the 1000w setting on, without dealing with extreme temps. I use a 630w cmh, and during the summer months i also struggled with high heat. It kept my humidity levels down while the light was on, but I also ran into high lights off RH. Environment is the toughest part to get right without AC and de/humidifier units imo. Only suggestion I can offer in that department, without AC is run your exhaust fan at a higher cfm, and exhaust the hot tent air into another room allowing you to bring in cooler air into the tent. Either that, or a cool tube for your lamp if you plan on using 1000w.
Your right about the PPM. The lower ppm your tap water is, the more nutrients you can add to your water/res to achieve your desired PPM for your plants. This is the reason many use RO water, as it has a very low ppm to start with so you know your starting point, and exactly the PPM of nutrients in your final mix.
Early veg I would aim for 300-400 ppm
Full veg - 450-700 ppm
These numbers will increase as you enter the bloom stage.
Some strains are heavier feeders, so keep that in mind that one mix for one plant might not work for every plant but if you start low and increase when needed you should avoid any burn. When you start mixing your nutes, aim to keep your pH around 5.8-6.0 .. Certain nutrients become more available at different pH's and keeping in this range should prevent much trouble. Mix your nutrients, then adjust pH if needed.
Your certainly going in the right direction! keep it up and you'll have some great smoke come harvest time. Nice strains by the way, look forward to some pictures.
