Beautiful plants, you are making me jealous ;-)

I previously mentioned to you, I may have some questions in the future. For now I'm only growing indoor lettuce, since it is the simplest, and while I grow quite a lot and my lettuce looks great from far away lol, if you look closely you will find some outside tip burns. In some cases quite a lot :-(

I did some searching on the internet and I can see there are all kind of possible reasons for it, but generally tip burns happen because of calcium deficiency which can happen because of one or more of these combinations:

• not enough calcium or magnesium
• high temperature & low humidity
• low temperature & high humidity
• high sodium content
• too high ppm (TDS)

Ideal TDS should be between 500 and 700ppm
Mine is around 900 but my tap water is 240 so nutrients adds less than 700. Now I wonder, should I decrease the nutrients solution a little bit to lower concentration?

I'm doing Kratky setup, no air. But solution seems clear and roots white enough. Humidity is on a low side, that's how it is here, but temp is not too high.

Do you happen to have any suggestion, tip?
Btw, would you happen to know, which lettuce is more resistant to noob mistakes, can tolerate more abuses and be more resilient for tip burn? ;-)

My solution per gallon: 2g masterblend, 2g calcium nitrate and 1g magnesium sulfate (epsom salt)

p.s.
Hey, @fuzzyvest, what about upvote for me? ;-)))