water temps

not too warm.. not too cold.. a goldilocks zone, you could say :P 65-72 is probably safe. Colder holds more O2, but too cold will slow down roots. Too warm invites pathogens and holds less O2. 65F wouldn't be optimal to seedlings and clones, but would be fine for mature, well-rooted plants. Dry nutes? Make stock concentrated solutions to ease your pain. Do 100:1 of normal dose relative to volume of your container for the stock solution. You'll need 10mL per L or 1.28fl oz per 1 gal. Metric is much easier to measure out due to nice even numbers that will more often match up with existing measuring lines and less guesstimating. I use 1/2 gallon containers. I put 50x my normal dose into it (1/2 gallon x 100), and then i have a measuring cup with 10mL intervals marked. I add 80mL to my 2gallon tanks, that also have a 8L mark. Easy as that. 50-gallons worth of nutes pre-mixed. When my rez is going i add nutes relative to the refill amount. If i added 30 gallons, i dissolve 30gallons worth of nutes into the 1/2 gallon before i dump into rez. Refill, mix nutes, let it sit overnight to fully dissolve, then add in morning. A couple hours or a lot of shaking can do it faster, but it can be on a relaxed pace either way. This way i can also use some warm water to help some of the harder to dissolve stuff go into solution. It'll be room temp by the time i dump it in, and even if not it is 1/2 gallon vs 45+ gallons in the reservoir. Not going to impact the temperature much nor o2 level. The powerhead keeps the water churning around and up and down. Gasses dissolve almost immediately. A churning surface will oxygenate more effectively than bubbles. And, if your nutes are liquid already, you shouldn't worry much. It doesn't take much to mix in something that is already in solution.

Make it just about 22*C ,should be close to your growing environment in your tent, happy growing.

ideal solution or plain water temp is 64-71f ( 18-22c)

It's more about soil temperature itself, who should be between 10~24°C (50~75°F). So room temperature water is usually enough, but you could use colder water to regulate a too hot soil. Long answer: https://www.researchgate.net/publication/323685894_Effects_of_soil_temperature_on_Some_Soil_properties_and_plant_growth

I prefer room temperature not to cold to make sure all the nutrients break down correctly and it’s around the same temp as my growing environment