First time grower problems help

Hello all so first timer here and would appreciate any help. I currently have two plants about 3 weeks old, the one is doing pretty good and haven't had much problems with it. The other has been getting burnt tips that started on the lower leaves eventually the lower leaf will die and work it's way up to the next set of leaves. I've done a ton of research and only thing I can think of is nitrogen deficiency,although I may be wrong. Any help would be great. Grow setup 2 leds 150 watt and 50 watt, watering with about 6.8 PH water, using MG organic choice potting soil. Which may be the problem lol. I haven't given them any nutrients but I do have some on hand, being only 3 weeks old and in MG I was afraid to feed them any nutes. Any ideas? Thanks and take an easy on my I'm still a noob

Ya MG sucks what I'd suggest imo is to run about 1 gal through them p.s. you should always start plants in final pots due to the unnecessary transplant stress and it looks like early stages of cal mag deficiency when you water I'd dose feed it that here is a link that will help you identify any problems in the future

https://www.google.es/search?q=diagnosing+problems+with+cannabis+leaves&client=firefox-b&biw=1906&bih=946&source=lnms&tbm=isch&sa=X&ved=0ahUKEwi6quny9ZjQAhWDxxQKHTEYBL8Q_AUIBigB#q=diagnosing problems with cannabis leaves&tbm=isch&tbs=rimg:CRvyUg5PnV1QIjjUh-FSldj-RKcAVk2h5reJqyhnb0tjDpy7-0vJENiG1XkTBU3ZKRpl3X4yU_1Z_1jtuugWQwidXleSoSCdSH4VKV2P5EESkvfa2XYnrFKhIJpwBWTaHmt4kR5EuzRBC8QzsqEgmrKGdvS2MOnBESIMKZefzVDyoSCbv7S8kQ2IbVEcMF1PiSo9r1KhIJeRMFTdkpGmURwj81zqmX58oqEgndfjJT9n-O2xFIGii_15vrplyoSCa6BZDCJ1eV5EVZGXav6jfFy

compost is probably too hot, just let um burn it off, i would not flush you may release more nutes, starting plants in the final pot slows growth as the wet/dry cycle takes longer, pot up as the roots fill the pots out, = more oxygen to the roots

I agree with bob but would also check ph of soil as the mg organic usually ends up with high ph.

I highly disagree on that statement when you start in the final pot you don't have to water ALL the soil just 4"off the base of the plant and every 4-5 days and the explosion of roots is inevitable I'll post my plant from seed in final pot till present 51 days old today

pH is to high for one thing, needs to be 5.8/6.0
Hth