You're not going to kill the plants and tbh im surprised those are still alive as most plants do not do well in hard water especially as high as yours.
What tds meter are you using?
55 gallon
No c02
Tds 138
Kh 4
Gh 7
Nitrate 25
Ammonia/nitrite 0
We all make mistakes as I still do, tank is still a work in progress, if you look at my anubias equilibrium actually burned them abd I had to do a massive trim
https://imgur.com/gallery/PNLiQvj
Don't get discouraged as heck I don't even really know how to reminerialize RO water
If you could, fill a cup with tap water and set it out on your counter for 24 hours. Then test the pH, GH, KH and TDS with your liquid API test kit. I'm curious as to what an accurate reading of your tap is. I'd hate to see you chasing parameters around with RO and additives and killing fish and plants if it isn't necessary.
I keep a tank with low light plants and fish and my water parameters are......
8.2 pH
KH 10
GH 10
TDS 320
Nitrate 20-40 ppm
No c02
Thrive liquid fertilizer
That's the meter I use. It's pretty accurate unless something is wrong it.
I have a very simple test I'd like you to do, test your RO water with your tds pen and make sure it's close to zero, since RO water can be 3-10
This is my tds meter it's ultra accurate, just curious as him testing the tds at such high levels if it might of threw out the calibration, also want to make sure his RO water is indeed 0.
Don't even need a tds meter really unless you're into shrimp.
HM DIGITAL TDS Meters TDS-3 Handheld Temperature TDS ( PPM ) Tester, 0 - 9990 ppm, 1 ppm Resolution, +/- 2% Readout Accuracy Testing Water Quality For Hydroponics Aquariums Pools Drinking etc https://www.amazon.com/dp/B01FXRC354/ref=cm_sw_r_cp_apa_i_gs.HCbS6TSJF0
Okay another side note that a pH of 6.2 is not good, yes Some fish have to be in those conditions, beneficial bacteria starts to die off at a pH of 6, why are you running such low pH in your tank, the fish you have like a pH from 7-8Ok as of tonight with a 5 gallon water change so I don’t shock the fish.
PH 6.2
Ammonia 0 ppm
Nitrite 0
Nitrate 50
TDS 1162 (confirmed tap water is 384)
GH 50
I didn't see discus in your tank but okay yes that makes sense but you don't want to keep discus in a 20 gallon tank.Was told discuss prefer 6.5 PH and the other fish will be fine anywhere from 6-7 PH
Says 20 in your postIt’s a 60 gallon tank haha
Says 20 in your post