tips are turning yellow, what do you think?

I have 4 different strains under a 1000 watt mh. 3 of the four are looking good but one is hurting a little.

They are 27 days old from seed today. I started off in a 1 gal pot of fox farms deluted with seedling soil. After 14 days I transplanted into 5 gallon pots with fresh fox farms. About a week ago she slowly started yellowing on the tips. Seems to be mostly the top half of the plant only.

Ive been watering them all on the same schedule with only tap water about once every 4 to 5 days. Tap water ph is 7, and ppms are 180, is she hungry or does this look like a deficiency. I want to flip to 12/12 soon but need to get her going again.

I have flora grow and micro, and I have fox farms grow left over. I also have some liquid cool bloom. I havent picked up any bloom nutes yet. They look worse in person then in pics.

early stages of magnesium.def. Oyster shell flour can take care of that. Kelp / aloe foliar as well.

I have some cal/mag, should I use that? Any dose recomendations. Seems kinda odd that she is the only one needing the extra mag. I guess this strain just cant get enough mag from the FF?

FF lacks cal/mag, you have to supplement it in. Id start the bloom nutes and you'll watch it fix. I start my bloom nutes 1 wk before 12/12

4Dexter2Morgan0 said:

I have some cal/mag, should I use that? Any dose recomendations. Seems kinda odd that she is the only one needing the extra mag. I guess this strain just cant get enough mag from the FF?

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cal/mag will work fine. Add 1 or 2 ml/gal, add it to all your plants.

Thanks guys, I hit them with 1 ml per gal for now. Im going to give them another week before i flip them to 12/12. I need to switch to the hps builb cause I have a think different auto in the mix an its already throwing buds. Unfortunately she is going to have to receive the 12/12 also.