2.1 everytime will likely cause a buildup.... (assumes north american 500 scale for TDS/ppm meter -- if ec is just 1/2 ppm with decimal point shift, it is '500 scale' which looks to be the case.)
in soilless, it is simple:
650-750ppm feed is typically as much as a plant can handle per 24hours without uncontrollable buildup in leaves and interfering with biological processes at some point too.
soil is more of an unknown... your EC can be much higher, but the plant cannot physically take in some of those molecules that cause EC to rise.... some microbe or other outside force much chelate/fixate or whatever.. break it down to a useble chunk of molecule or atoms...
in soil, if you want to fertilize every single time, you just need to ass lowe concentrations than if you do once every 2 or 3 irigations.... roughly the same amounts will be added per week of month regardless of application interval. You'll probably do better with on demand, but there may be minimal difference between that and say 1/2 or 1/3 irrigations. you'd need some existing research to have a clue about that.
so, as the plant ages, it'll show how close you are to a healthy feeding regimen. keep track of what you do... try to use the same products (soil, amendments added etc) so that what you learned will be applicable the next time --- sometimes you have to change some foundational things around and expect to adjust a little to it if you do.
eventually it'll be second-hand for you to do.
try soilless grow sometime... mindlessly add 650-750ppm irigation each and every time with 10-15% runoff waste water (down drain or toss outside) the moment you have a poper balanced feed, it is immediately applicable everywhere else in a resolved way... e.g. if i change brands of nutes, i can do the math and start with a balanced ppm mix of each molecule similar to what i used before and know it will work well, because a rose is a rose is a rose...
check out screenshot of my ppm beakdown in any diary. what you see is a bit lower than what i acutally use, but i jsut dont update the screenshot all the time because it changes based on observances and stage of life but never more than 5-10%. my full feed is closer to 720ppm. i sometime drop to 600-650 early on... when i reduce N to 120ish in bloom, that knocks it down a peg too.