Nut or pest problem? (Pics)

I'm not sure if this is a nutrient or a pest problem. I've got a few fungus nats, but not that many (I only see about 1-2 a day). I use Foxfarm hydroponic TIGER BLOOM at a little less than the package says. Water is from a reverse osmosis and they are fed twice daily from a 15 gal reservior which is changed weekly. PPM is around 1200~1250 and the ec is 1.75~1.85.

At first I thought it was heat stress as one plant is extremely tall and the other I had on a bucket to keep the height similar but ended up burning both. Now the taller one is on the ground being fed by hand with identical nutrient.

My concerns are with the brown upturned leaf tips and also the brownish spots that are developing in the leaf margins.

Any help would be great help!

I've gone ahead and stopped feeding them nutrients and instead giving them only pure water ph balanced to 5.6~5.8. I'm going to do this at least for two days, but am unsure if this is the appropriate amount of time!

I'm not sure about the nutrient burn, but the brown curling leaves are burnt from touching the light and the faded leaves are washed out from being too close to the light. Moving them down a little will help.

Flushing can't hurt them. Then wait and see how they respond as you add nutrients back.

Good luck.

Thanks for the reply mate! I've got them a good distance away now so I think that they'll be ok. I'll keep everyone posted on how the flush will effect them. I hope they'll get better soon.

I think I've got a bigger problem now. I've seen some silk-like string recently on a bud and I don't know what it is. I think it might be spider mights. I've not seen any, but tomorrow when the lights come back on I'll be sure to check very thoroughly.