Lower Leaves Yellow, Brown Leaf Tips

White widow, about 21 days old, vegging under 400W MH. Feeding them quarter-strength Hydragro in distilled water, on the advice of my grow shop. I'm thinking it was bad advice. The lower leaves on several of them are suddenly turning yellow with brown tips, and drying up from the ends inward. Other than that, they look healthy, albeit a little shorter than I'd like them to be at this point. But basically healthy.

Anyone have an idea what this is? Sorry, the second pic is a little out of focus - but the leaves on that one look identical to the one that is in focus, just more advanced. My gut feeling based on my experience with outdoor grows is that it's the nutes, and possibly overwatering. Can anyone confirm this?

Thanks in advance, all you indoor hydro geniuses!

it looks like it's not getting enough nutes....thats usually a sign when the bottom leaves get like that....

Thanks, but given that I'm already feeding them quarter strength nutes and they're only 3 weeks old, it's hard to believe they're not getting enough nutes. I appreciate your help, but it just doesn't sound right. Anyone else have any ideas here?

Skunk Baxter said:

Thanks, but given that I'm already feeding them quarter strength nutes and they're only 3 weeks old, it's hard to believe they're not getting enough nutes. I appreciate your help, but it just doesn't sound right. Anyone else have any ideas here?

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what i mean is it could be a nute lock out...have you checked the ph of your water?

I wouldn't give plants that size anything but plain water.
I can't see the cotelydon leaves in either pic but they provide all the nutes the plant needs until they are spent.
Funny enough it doesn't actually look like nuteburn from what I can see so I'd also look at the ph of your water. Always check it after any nutes have been added as some of the nutes I've used have made a big difference to final ph.

Its botrogen

Sorry.. its nitrogen burn buddy.. i just did this to one of my 30 day olds and the botton two sets turned yellow overnight and burnt today because 3 days ago i gave em too much blood meal... which is 12% nitrogen.. flush it and youll be fine