Leave drying at the tip and turn brown. Pls help

This is my first grow from seeds
Strain: Fem white widow seeds.
Nutrient: Maxibloom 1.3 EC, PH 5.8, Rootxplorer 5 ml per 5 gals, 15ml cal-mag per 5 gals.
Soil: Coco
Plans start out very nice then lately I have this problem.

I’m thinking they look a little magnesium deficient, this is often a problem with coco coir. You could try increasing your cal-mag a little, you might also think about adding a little zinc/sulfur supplement as well, as the type of leaf damage could be pointing to those deficiencies as well. but coco is notorious for causing magnesium problems, also be sure you are not over watering as your coco could do to be amended with more perlite in it. Make sure the coco is almost totally drying out between watering. You can do 40% - 50% perlite in a pure coco mix. Too wet of roots can contribute to the above deficiencies as well.

Epsom salts would increase your magnesium and sulfur. You can try adding some of this instead of increasing your cal-mag. Keep in mind these will all increase your EC, so some adjustments might need to be made and adjusting and slightly reducing some of your other nutrients might be necessary to keep your EC in a nice range.

Cannot be a magnesium deficiency if using CalMag

Look like it is too wet, all the time. I am not a Coco grower; So I am giving my best guess. What is you watering schedule? Might be a fungus.

I water once every 2 days. I just transfer from small cup to 1 gal pot. Possible that plan got shock from moving? Thank you both for responding. I add little more cal-mag and zinc/sulfur as suggested and hope they will recover in few days

Coco is notorious for absorbing calcium magnesium and not releasing it to the roots, creating a nutrient lockout of those nutrients, and you need to use more/extra cal-mag to compensate. It is often prepared and stored right near the ocean where the coconuts grow and lots of salt water can get into the coco coir, some newer more expensive brands are flushed of any salt water that the coco sometimes absorbs as well as adding calcium and magnesium, however most are not. If you flush the coco with a high in calcium hard water, this can help add some of the calcium to the coco as it replaces sodium ions but magnesium usually still needs to be added with Epsom salts.

Get a feel for the weight of the coco totally waterlogged and the almost totally dry, feel the weight of the container the plant is in, and then do not water until it is almost totally dry to prevent over watering.

I think they should recover just fine.