Dwc, first time.

Could be a number of things due to root issues from the times you've allowed the reservoir temps to go beyond 70 F and possibly even light leaks. At times even as high as 78? I've grown DWC for years and from my own experiences maintaining proper reservoir temps has always been the thing I battle with the most. I personally never let them go beyond 70 F. If things get too heated under the hood, roots begin to suffer, then that's when deficiencies kick in and the plant's growth is slowed down. Were the roots affected; browning, funky-smelling, slimy roots? If so, have you treated them and how do they look now? What are the room temps and R.H.?

 

What’s the water temp In your buckets?

 

This is still in veg.

Look at the clones.

 

It could be nute burn that’s showing on the leaves. What nutrients are you using? And you usually don’t need even half as much as the instructions say. Remember the nutrient company wants to sell as much as they can. Personally I’d go in and clip any water leaves left along with the burnt leaves right at the stem so the plant focuses on the healthy parts and doesn’t try and repair damage.

 

I want to say nute burn, but the majority of the affected leaves are the older, bottom leaves and the deficiency looks more like an advanced potassium deficiency and the beginning stages of magnesium deficiency. I still believe all that was due to nute lockout from the root issues earlier on. If you treated the roots and washed them out carefully and you're keeping the reservoir temps under control (below 70 F), then all you can do is wait for the damage to heal in time. 300-400 ppm isn't all that too high for the stage they're in. However, I'd keep them in the 300's for now while they recover. Another thing I noticed your buckets have that I personally wouldn't recommend when growing in DWC. It's those little blue hoses that stick out of the buckets to tell you the water level of the buckets and help with draining the buckets as well. I'm sure they do help with those things, but IMHO I think they're bad in exposing the water to the lights and thus helping the water get heated faster, etc. I agree that those really bad completely damaged leaves should be snipped off. No point of keeping them there making the plant look ugly lol.

 

Hydro growers learn how to grow root systems. The girls just fallow and turn into beautiful heavy yielding plants. Mistakes are your friend when your just starting!! That’s what your gonna learn the most from. Mostly because it’s so fuckin aggravating

 

Do you veg in a different system or in the buckets as well? If you do both in the buckets? I’d recommend setting yourself up a flood and drain table for your vegging plants, then when ready for 12/12 move to your buckets. I build all my systems and have the most success doing it in 3 steps (also allows you to stager your grow) germinate/clone - veg - flower. That really allows you to dial your focus in on the root growth. And catch any issues before they have a chance of becoming a problem. I use a aeroponic/fog cloner then when ready they go to flood and drain until ready to be moved to 12/12. Sense the nute and lighting requirements are so different for each phase it really lets you capitalize. .jpg[/IMG]

As you can see I also bonsai my plants, top, fem, break and tape, low and high stress training etc etc. non of which is necessary but when done right is definitely a good practice.

A lot of indoor growers try and mimic Mother Nature. Personally as an indoor hydro grower I like to create my own eco system.