Mephisto Mango Smile Problems

[Raven1469]

Hello everyone! I've been having the same problems for the last few grows, so it's not just this plant, and I can't figure it out. It's making my love of growing go away due to frustration.
Week 3 from sprout OF w/ 1/4 1 gallon pot of perlite. NOTG nutes that I started yesterday 18/6 light schedule. 17 DLI. 77F/77 humidity. This has happened with my last three plants. Didn’t have the issue before. I have noticed a lot of calcium buildup from my tap water ran humidifier. For watering I use tap water that I let sit out for 2-3 days before using to water plant.
I've let them grow out in the past and its a whole plant issue. The leaves eventually dry out and die.
Thanks everyone!

 

[N/A-Greengo]

It's very important to PH your water at 6.5 so nutrients can be properly absorbed.

 

[FarmerJake]

 

[Lil Dab]

For watering I use tap water that I let sit out for 2-3 days before using to water plant

Do you have a way to measure the ppm and ph of the tap water? Is this well water or city water? I have really high ppm and ph tap water 300-400ppm 8.4 ph… that was giving me issue I’ve since switched to using RO water mixture

Also OF is a bit hot for starting autos in directly but can be done… They shouldn’t need anything added till at least 5-6 IMO with OF