Is your basement temp stable or does it fluctuate during summer? Same with humidity? So your basement is roughly 20' x 30'?
That's big for a 3 x 3 but it'll work. Most growers have issues with heat but it seems like you are lucky in that you don't have to contend with that. A small space heater on an inkbird or some other way of regulating temp should be all you need to be able to control the temperature you want your plant to be at at that particular stage of growth. Try and figure out how you can exhaust the air in your tent outside of your lung room/basement so that only fresh air is entering the tent.
If your basement is averaging 80% humidity on average you are going to need a fairly large dehumidifier. I use a DIY auto irrigation system so I use dehumidifier condensate that I have draining into my reservoir for feeding the plants.
IMO, you're underpowered when it comes to your light. I'm shooting for 30 watts per square foot in my 5 x 5. I have 25 sq/ft of tent space x 30 watts = 750 watts. For me to properly power my flower period 750 watts is where I want to be. For you it would be 270 watts. Your light is 100 watts. Lighting is the one area that you really don't want to skimp on as it powers everything in your grow. I'm currently running two 275 watt COB style lights, similar to your SF-1000, in the 5 x 5 but will be upgrading to a bar style light to accomodate my grow style. I'll probably go with a Gavita 1700E Pro if I can find a good used one because they're pricey. I'm also looking at a Growers Choice ROI-E720 or a Medic Grow Smart 8 if I can't find the Gavita.
One of the things that drives vigorous growth is high PPFD and balanced nutrition in a well draining medium. With a properly powered light you can use the dimmer function to apply the right amount of light at the growth stage the plant is in to push it to its maximum potential. If you don't have a light meter to measure how much light is hitting your canopy I suggest you download an app like Tent Buddy or similar. This way you can accurately measure the amount of light your plants are getting and can adjust accordingly depending on stage of growth.
I like to use DLI(Daily Light Integral) as a guide to how much light at what stage of growth I want to give to my plants to maximize their growth and keep them as healthy as possible so that when they're in flower they have the foundation they need to grow big fat colas. I'm currently running an AC Infinity T6 6" fan w/Controller 67 in the 5 x 5 but I think I need to upgrade to their T8 - 8" fan w/Controller 69 pro wifi for better airflow in that size tent. The T6 is doing the job but I'm putting it through it's paces. I don't like to run gear full out as it shortens their life span.
Pic of a harvest I just did in the 5 x 5. 3 different strains/cultivars.
