Apparently Suddenly Clueless

Running a 2 bucket RDWC with a chiller. (I live where its hot even in winter). I cannot diagnose the problem here and would love some help or guidance. This is the 4th plant that has started to yellow. I have adjusted everything I can think of...Raising and lowering the light, light strength, Water temp, CalMag, Nutes but can never quite figure it out by week 5-7 where the plant looks awful and I pull it. Below is a pic and my current plant info.

Thank you so much for any assistance or guidance.

- Week: 3
- Nutes: TPS Nutrients
- PH: 6
- Water temp: 68F
- EC: .7
- Humidity: 65%
- Temp night: 70F, Night 65
- 4x4 grow tent
- Light: Spider Farmer

Looks awfully small... are the roots in the water? Auto or photo?

Thank you for the reply: Yes they are in the water and Photo

Have you tried upping the feed, if so how much?

Do the failed plants all look similar to this, and if so, how does the affliction progress?

Iricana said:

...
- Humidity: 65%
- Temp night: 70F, Night 65
- 4x4 grow tent
- Light: Spider Farmer

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70F is the daytime temp?

If so, another 10 degrees of warmth would work wonders.

I have not significantly increased the feed. Most early weeks all call for similar amounts if you go by the TPS provided feed chart, so no significant increase in feed. Yes the failed plants all followed a similar process. I'd would say the new leaves look good for a few days as they mature then start to yellow slowly. It progresses as new leaves grow and older leaves get bigger then eventually drying out starting at the tips and moving inward.

BTW - my mistake this is week 2

Billy the Mountain said:

70F is the daytime temp?

If so, another 10 degrees of warmth would work wonders.

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Thank you for the replay. My apologies 75F is the daytime (I put the night flux there)

I would say maybe up the feed, maybe some calmag.

I believe that is mobile nutrients leaving the old growth for the new growth, in this case magnesium possibly?

How often do you change the res, or do you just top off?

Tolerance Break said:

Have you tried upping the feed, if so how much?

Do the failed plants all look similar to this, and if so, how does the affliction progress?

Click to expand...

I have not significantly increased the feed. Most early weeks all call for similar amounts if you go by the TPS provided feed chart, so no significant increase in feed. Yes the failed plants all followed a similar process. I'd would say the new leaves look good for a few days as they mature then start to yellow slowly. It progresses as new leaves grow and older leaves get bigger then eventually drying out starting at the tips and moving inward.

BTW - my mistake this is week 2

Tolerance Break said:

I would say maybe up the feed, maybe some calmag.

I believe that is mobile nutrients leaving the old growth for the new growth, in this case magnesium possibly?

How often do you change the res, or do you just top off?

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Thank you. I will try some cal mag and upping the nutes. I change the res every week and pump out old and bring in new

Iricana said:

Thank you. I will try some cal mag and upping the nutes. I change the res every week and pump out old and bring in new

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It sounds like youre doing everything right, so I am genuinely optimistic that the changes needed to get her going are very small and specific. I hope everything works out for you!

Tolerance Break said:

It sounds like youre doing everything right, so I am genuinely optimistic that the changes needed to get her going are very small and specific. I hope everything works out for you!

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Thank you for your help. It's much appreciated and good to know I am not going too crazy.

75f is still on the low side in veg.
What's the exact light and what are you running it at power wise and amount of hours wise?

0.7 is on the low side of the charts recommendations.
What's your water ? Tap or RO?

As others have said, with LED you need the Temps in low 80's. Mine run 82-84.

coreywebster said:

75f is still on the low side in veg.
What's the exact light and what are you running it at power wise and amount of hours wise?

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Spider Farmer - SF-2000 running about 18 inch off the plants (2) running at 100% power /18/6 hour

Iricana said:

Spider Farmer - SF-2000 running about 18 inch off the plants (2) running at 100% power /18/6 hour

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Dim them or raise them and get your temps up to 80f , they will be happier and transpire better and uptake nutrients better.

A bit of calmag wouldn't hurt, but you've not said if your on RO or tap.
But they'll do better in a warmer environment with a bit less light

To me it's slow light burn, which affects the older leaves because they've been under the light longer.

I generally use mh for veg because then I can veg low 70s and I don't have to add a heater, but my flower tent was empty for a full clean this round and I did the final training under my LEDs, 600w bar lights, set on 25% , 80f, plants were very happy, which they weren't at mid 70s on previous attempts at vegging under LED

You don't need that high temps when using LED. Lower temps (lower transpiration to be precise) can be compensated with higher EC. You have to test what works for your set up but 2,5 mS/cm is not unreasonable.

Lou66 said:

You don't need that high temps when using LED. Lower temps (lower transpiration to be precise) can be compensated with higher EC. You have to test what works for your set up but 2,5 mS/cm is not unreasonable.

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I'll have to try that

Raising the EC makes sense if you cannot raise the temperature; otherwise raising the temp is the better solution.