HELP! Yellow Leaf Tips on Seedlings - Hydro DWC+Top Feed

[Randomuser123]

Hey there,
my very young seedlings have yellow leaf tips and since its my first time doing hydro (DWC+Top feed based on Top-Fed DWC Cannabis Setup Guide – Bubbleponic) i figured i will ask for the thoughts of you guys here. I am using 2x OxyPot 70l versions for the DWC system, 2 seedlings per reservoir. Each reservoir has its own air pump with four air stones and its own water pump for the top feed.

Roots are not long enough yet to reach all the way through the net pot into the tank.

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What i tried / checked with reference to https://www.growweedeasy.com/wp-con...diagnose-chart-cannabis-problems-symptoms.jpg

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• Using LED 2xSanlight EVO-120 (2x250W) on 120cmX120cm area. Initially i had the recommended distance of 30cm but after seeing yellow spots i increased to 40cm. Also its dimmed down to 20% (minimum) - i have vents for circulation as well as exhaust and filter setup - i could increase air circulation by increasing exhaust fan, if that matters.
• Also checked ph, which is between 5.9-6.1
• Top Feed is setup so it expels water directly into the cube (testing root riot & easy plug) - possible root rot within the cubes?
• Air Temperatur is between 22-25°C (71.6-77°F) / Water Temp 21-23C° (69.8-73.5°F) / Humidity betweedn 50-65%
• Potential Watering Problems? Back to Top feed?
• During the first reservoir change i started with nutrients (as written in the guide) - started with 1/4 of recommended amount (using TripartFlora, TripartMicro, TripartGro from GHE)

​Picture of the seedlings here (2x Blue Haze, 2x Lemon Power Haze)

In the pictures you will see some seedlings have 2x tubes in the pot and the outer/upper tube is not feeding into the cube, i just put the tubes out of the water and fixed them in the pots)

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Any ideas, suggestions or constructive feedback is appreciated! I tried following the provided format when asking for help, if anything is missing or if additional information is required, please do let me know.

Thanks all in advance!

 

[9fingerleafs]

Kinda look like over watered. I've never done DWC so I'm basing my observation in my coco set up. Over watering it's not really about the water, it's about the oxygen available to the roots. Are you using a pump and air stone?

 

[Randomuser123]

Using an air pump with four air stones - but right now the seedling are too small and the roots not long enough to dip down in the reservoir. Maybe ill put the water pump of the top feed on a timer for now so it can drain a bit better but doesnt dry out.

Or maybe reduce pump rate of the water pumps to reduce actual top feed?

 

[Bluey]

Can you measure the EC of the water you ate using and the EC after adding nutes?

 

[Randomuser123]

Right now I am not able to measure EC, but will be able in a few days and then ill update. Have to admit i havent paid attention to EC as much as i did with other factors

 

[9fingerleafs]

So the top feed is running non stop? 🤔

 

[Randomuser123]

Yes indeed - well i put them on a timer now, but they were running non stop before. In the bubbleponics guide I am following it said to run water pumps 24/7.

After reading into that it seems people can be successfull with both methods - 24/7 and intermittent schedule, switched to intermittent now and will see