If you want to turn HID lights on and off, a cheap little 5v relay isn't going to cut it, and I know this from experience. When I tried it before, within 2 days, the relay had fused closed, and the light stayed on. After doing some research, I found out I needed something called a contactor, basically a heavy duty relay. So off I went to Home Depot and a few other places, but nobody knew what I was talking about :(
While I was at the local grow shop picking up some ProMix, I thought why not ask if he knew what I was looking for. Turns out they had ONE, although it took him a bit to find it.
While a 600W light at 120v will only draw 5 amps, it's when you first turn it on that it draws quite a bit more. This relay is rated for 40A@220v, so roughly 20A at 120v. The coil voltage is 120v though, so I can't control it directly from an Arduino digital pin, so I'll use a small 5v relay to switch the 110v on to the coil, which in turn will switch the main 120v on for the light.
One of the main reasons for wanting to control the light in the flower tent rather than leave it on a timer, if the exhaust fan were to die, or the ducting came off, the tent will get very hot very quickly... the plants wouldn't last long. This way, if the temp rises above a certain threshold, I can shut the light off, saving the plants. I've also read where a lot of people swear by using a contactor, even if driven by a timer, just to avoid a fire hazard with the timers.
I also ran across some nice buckets at Home Depot that I'll be using as pots. I'll drill some holes in the bottom for drainage, and they should provide plenty of room for a nice root system, and therefore a nice big bushy plant. Then I tried to find some trays to go underneath to catch runoff, and couldn't. At least, not until we went through the dollar store and I found some dish pans for $2 each. So $4 for a bucket, $2 for the tray, and I'm set with a trial run of 4 plants.
It is with these 4 plants I will set up the automatic watering to get started.
But first, after re-installing windows, and all the programming tools, everything I upload to the ESP8266 sends it into a reboot frenzy due to the watchdog timer. I finally gave up and went to bed last night, and actually for the first time in ages, slept for more than two hours... We spent today doing our shopping and stuff, so tonight I'll be getting back at it. Right now, the sensor modules are working without issue, so there is no real rush to get things compiling properly again, but the sooner the better.