Seedling leaves showing weird symptoms

hi all,

i've got 5 seedlings growing in my balcony.
they're growing in small silicon seedling cups that are similar to those party cups some people start seedlings in.
soil =debco premium potting mix (slow release fertilizer in it)
water = tap water that i've let bubble for 2 days in a bucket in my balcony to remove the chlorine.
strain = random seeds given to me by a friend.

most of them are going good but all of them have had problems with the first set of real leaves. by that i mean the first set of leaves that sprout after the cotyledons appear. they start turning pale, then yellow and usually the tips start dying and turning brown. i also noticed that on some of the leaves, there seemed to be parts where something's eaten through it to the point the leaf is pretty much transparent.
any help in diagnosing either problem would be much appreciated.
here are some pictures to help.







thanks all,
buddy

I find that the soil with time release fertilizer can cause alittle nute burn on seedlings. I am no expert but that is my guess.

Also, does it get cool during the evenings outside?

yeh that's what i thought too, that ever time i watered them, the slow release nutes
were being released and are too strong for the seedlings to handle. i guess they'll
make it through that.

as for the evenings, the temperature usually drops to 20ºc - 22.5ºc with humidity usually around 60 - 82%.

I'll 2nd that!! But if you hang on they will pull thru

yea you should be able to get threw that. u arent adding nutes r u? i use mg soil for seedlings ant clones and have never had aproblem. maybe there is just too much nutes in the soil