Struggling with my new DWC system

[d@rkAng3l]

I have some experience with a small DWC setup and decided to upgrade to a five-bucket system for a better yield. I moved my seedlings over and have been struggling ever since. My plants have yellow outer fan leaves and I am not sure what is causing it. I am using two Spider Farmer SF100D lights in a 6x4 tent. My pH is stable between 5.6 and 6.0 and the water temperature is between 67 and 70 degrees.

I've been increasing the PPM slowly to avoid nut burn and it is currently at about 400 after five weeks. New roots are growing from the rockwool into the hydro rocks. I noticed today that the PPM in one of my plant buckets was 303 while the main reservoir was 215 and I am not sure if that is a problem. The bucket water just touches the bottom of the basket.

Do I need to keep the reservoir at a higher level than the plant buckets? Can I turn off the recirculators for a bit to see if that helps and what do you think is causing the yellow leaves?

 

[Starfru1t]

I have some experience with a small DWC setup and decided to upgrade to a five-bucket system for a better yield. I moved my seedlings over and have been struggling ever since. My plants have yellow outer fan leaves and I am not sure what is causing it. I am using two Spider Farmer SF100D lights in a 6x4 tent. My pH is stable between 5.6 and 6.0 and the water temperature is between 67 and 70 degrees.

I've been increasing the PPM slowly to avoid nut burn and it is currently at about 400 after five weeks. New roots are growing from the rockwool into the hydro rocks. I noticed today that the PPM in one of my plant buckets was 303 while the main reservoir was 215 and I am not sure if that is a problem. The bucket water just touches the bottom of the basket.

Do I need to keep the reservoir at a higher level than the plant buckets? Can I turn off the recirculators for a bit to see if that helps and what do you think is causing the yellow leaves?

this sounds like a nutrient deficiency, which is why the outer leaves are turning yellow.
A PPM of 400 after five weeks is extremely low, your plants are basically starving.
You should be aiming for a PPM of at least 600-800 at this stage of growth.
The discrepancy between your reservoir and the plant bucket isn't a huge deal at these low numbers, but it's a sign that the plants are sucking up water faster than nutrients, which is another indication that you need to feed them more. Start slowly increasing that PPM now

 

[sudoku-girl56]

this sounds like a nutrient deficiency, which is why the outer leaves are turning yellow.
A PPM of 400 after five weeks is extremely low, your plants are basically starving.
You should be aiming for a PPM of at least 600-800 at this stage of growth.
The discrepancy between your reservoir and the plant bucket isn't a huge deal at these low numbers, but it's a sign that the plants are sucking up water faster than nutrients, which is another indication that you need to feed them more. Start slowly increasing that PPM now

Thanks for the insight! I'm new to hydro and trying to help my brother with his first indoor grow, he's got yellowing leaves and we were stuck. If I may ask, when bumping up PPM, is it better to go slow over a few days or adjust all at once? And does water temp affect how well nutrients get absorbed? Just trying to avoid shocking the plants.

 

[HELYAB]

It sounds like your system is still running at seedling strength. Four hundred ppm after several weeks is very light, so the plants are likely drawing most of the available nitrogen and magnesium out quickly. You can safely bump the reservoir up to 600-800 ppm by adding more base nutrients and a little cal-mag; just do it gradually over a couple of days and watch how the plants respond. Try to keep your control bucket at the same height as the plant buckets so the water levels equalise, and keep the circulation pumps and air stones running so nutrients and oxygen stay evenly distributed. Water temps in the high 60s are fine, but if they creep into the 70s nutrient uptake slows and root problems can start. With a bit more food and good aeration the yellow leaves should stop appearing and new growth will come in a healthy green.

 

[Sarah_Seika]

Five weeks in and only 400 ppm? That's low. They're probably starving. Yellowing outer leaves = deficiency, not overfeeding. You'll need to bump the nutes soon or they won't catch up.

 

[black codez]

It is unlikely that such a low nutrient level would cause a lockout. The more likely reason is the water level. If it is too high and the roots are constantly submerged they can become waterlogged which can cause a lockout. The plants are likely droopy and adjusting the water level should help the roots to recover and the plants will perk up within a few days.