***Need help identifying problem***

Good Evening,
I am attempting to grow three different strains and am in need of help because the tips and sides of the leaves are starting to yellow. They are four weeks in vegans I am using Nectar of The Gods Soil, SLF100 and Nectar of the Gods liquid supplements. Ph of water is 6.3-6.7 and is on a 18 hour on 6 hour off light schedule. Please help me identify and fix this issue. Thank You!

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Just a guess, but from looking at the soil it looks like you water them a little bit every day.

You need to give the soil a good soaking then let it dry out over 5-7 days. The soil needs to be moistened throughout the pot if you expect the roots to search it out and develop.