Brown spots on leaf tips of old growth.

I'm with ezzjaybruh here.... his 29 diaries show he knows what he's talking about!

EC need to get up! I used these nutrients a lot when growing hydrophonics and I have never been under EC 1.0 I always started first week EC 1.0 and up this every week by EC 0.1 till you reach EC 1.8 (EC 1.8 is enough till harvest!!!). I always only used the 3 GHE nutritions with GHE powder pH minus and Dutch tap water. Last week flush and BOEM!!! Harvest big buds every time 😋 The reason your EC stays stable is because she is only using the nutrients thats she needs right now. A lot more N then P or K. So what you measure now is a stable EC but this is all old P and K. When cannabis plants are eating a lot in hydrophinics the pH will go up slightly too because the nutrients are a bit acid compare to the water. So when your pH stays perfectly stable you can see already that she barley eats nutrients. I like to play with the nutrients and always make the solution 5.5 and let it go up a little to 6 and then make it 5.5 again. This way other nutrients become available easier for the plant. Happy Growing! 😋

You are experiencing potassium deficiency. Brown straight tips is potassium deficiency. Brown curling up and in tips is nute burn. Dark green curling down is nitrogen toxicity.

I'm not overly skilled in DWC, but I would think your plants would like a bit more feed then 300ppm at week 3. The PH is on point congrats on that. Also may want to look into adding some calcium and magnesium to the lineup of GH trio. I think trio is enough but again not overly filmier with DWC, hopefully a hydro head chimes in and can help yea out. Good Luck! ***disclaimer, multiple people are answering all questions as there is a contest called GOTM, when a user is selected as the answer they get a point. Please see the contest page for information regarding the details: growdiaries.com/giveaways/GotM-August-2022 Please note, when you reply to anything on the questions part of Growdiaries website, no one will be notified of this. Not even if you use a "@" tag in their name. Best to reach out to them in DM using your inbox, it can be found in the bottom right hand corner of the site. It's the small paper airplane button, it will be highlighted green if you have new messages***