All in all, you need more instrumentation to know what to which conditions you are subjecting your plant. You need some way to measure the pH and ppm/EC of your water, a thermometer and hygrometer to know temp and RH, and some sort of light meter to measure your lighting.
Temp and humidity is no problem. You can get all sort of gauges for less than $10.
After temp and RH meters, the easiest (cheapest) meters to buy are basic moisture and EC meters. Those 2-pronged jobs you stick in soil to measure moisture work and are about $10 usd. An EC meter is about the same price but a tiny bit tricky. You want an EC meter, but you'll get a PPM meter in there too. (Some PPM meters do not include an EC mode - don't get one of those if you can help it.)
There are two PPM scales in use - 500ppm and 700ppm. (A pen on the 500ppm scale will read 500 at the same time a 700ppm scale reads 700. ) You want the 500ppm scale as most charts assume that scale. EC is EC, but it is also 2x the PPM when using the PPM500 scale. So you can get EC easily from the right PPM meter - except they may not tell you which PPM scale they use! I have one that has 700ppm scale and EC mode too, so i just change to EC mode every time I use it. Cost of pen was $12 usd.
After that, things get expensive. There are no accurate pH pens that I know of under about $50. I use a $75
Bluelab pen, and I calibrate it. I used to use a $15 pH pen until I found it was reading about 1 point high in pH. Be very wary of cheap pH pens. And know that the tips must be kept moist (in a special solution) when not in use.
And then we come to measuring the strength of your lighting. With LED's it's impossible to make any standard predictions. You either use charts from the manufacturer that give PAR values at certain distances - but these are given for full power settings. If you have a dimmer in use, you have no idea how much light the plants are seeing without a meter. Unfortunately a good PAR meter is the most expensive of all the meters here. FIgure at least $200 for a decent PAR meter. I paid $400 for my Apogee MQ-200. But I don't have to guesstimate my PAR values, I can simply measure them anywhere in the tent and adjust lighting as needed. All other meters are attempting to estimate PAR values indirectly, with varying degrees of success. I would not trust a phone app in particular, nor the little Lumen meter on one of those cheap 3-way moisture/ph/lighting probes.
As for your nutes, you need to know what you are putting into your plants, and you need to know the characteristics of your source water. For instance, here in Phoenix my tap water EC is over 400 because of the high amount of calcium in the water. It's actually too high for seedlings, particularly if you need to add some nutrients. Not so bad later in the grow for coco, but I use RO all the time because then I control what goes into it. I add 1.9ml/gal of
Calimagic since I'm a) growing in coco and b) using RO water with no cal/mag. I end up with EC around 250 at this stage just from the cal/mag. Nutes (currently) take me to around 1400, and I hold pH at 6.0. For me, it's all working beautifully.