Help with dwc issues. Seedlings turning yellow

G

GTConsulting

Member
Not much response in the newbies section so I’ll try posting/updating here instead. Hope this is okay?

Everything seemed fine until two days ago. Not sure what’s going on.
9gal distilled 1gal filtered tap
50ml 3% H2O2 added two days ago (should be all gone now)
pH 5.8
ppm 200, gh flora 3part
Res temp 71F
Tent 75F
Rh 40%
Rdwc with waterfall into each bucket
Air stones w/ 3.2Lpm air pump for each bucket
Mars tsw1000 light at 25% 10”
rockwool cubes are famp but not soaked roots touching water, the larger plant has one root poking just past the net pot
Water level 1/2” above bottom of net pots
Nutes are clear, no percipitates at all, but no longer cranberry tinted.
 

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L

Larry3215

Well-Known Member
Couple of questions.

Is that PPM the total or the amount over your base water PPM? I would assume your base water PPM would be pretty low with that mix ratio, but do you have a number? What is your tap water like? Is it so bad you have to dilute it that much?

How long has it been since you changed out the rez? That should be done every week to 10 days normally.

Run your fingers inside the rez along the walls and check for any slimy feeling. Slimy = bacterial growth.

What color are the roots?

Are the rock wool cubes sitting in hydroton or touching the water?

Normally the entire net pot should be sitting above the water - not touching it. The hydroton is only weted by the droplets created by the bubbles from the air stone - not by direct contact. The reason is to prevent stem rot, or damping off because thew stem stays too wet. Its super easy to have rock wool stay too wet without realizing it.

Everything else is close enough I think and shouldnt be causing the problems.
 
GBAUTO

GBAUTO

Well-Known Member
I agree with Larry.
I also use a grodan cube nested in hydroton in a 6" netlid.
If the net is submerged, it will wick the solution into the cube and create pathogen issues.
I always hand top-water until roots drop into the solution and then let the cube dry.
200ppm is pretty weak, especially for Flora.
They look hungry-increase the nute mix.
 
G

GTConsulting

Member
Larry3215 said:
Couple of questions.

Is that PPM the total or the amount over your base water PPM? I would assume your base water PPM would be pretty low with that mix ratio, but do you have a number? What is your tap water like? Is it so bad you have to dilute it that much?
Click to expand...
Total PPM measurement. Filtered tap measured at 240ppm, so it should be 24 once diluted w/ the distilled water. Added 10ml of each Flora nute to bring it to 200 total.

Larry3215 said:
How long has it been since you changed out the rez? That should be done every week to 10 days normally.
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5 days ago. Always added a bit of H2O2 to the res to prevent any type of growth and to oxygenate the water some more.

Larry3215 said:
Run your fingers inside the rez along the walls and check for any slimy feeling. Slimy = bacterial growth.
Click to expand...
squeaky clean

Larry3215 said:
What color are the roots?
Click to expand...
The tiny piece sticking out from the larger plant is white as can be. Same as the root sticking out of the rockwool when I checked the dampness of the rockwool yesterday.

Larry3215 said:
Are the rock wool cubes sitting in hydroton or touching the water?
Click to expand...
I have a layer of Hydroton on the bottom of the net pot with water covering 1/2 of that layer. Rockwool sits on top of that so it should be just above the water. Checked the cube yesterday and it was damp, not soaked. Had the water level about 1" BELOW the net pot 2 days ago cuz the leaves looked curled down and a bit heavy. After lowering the water level for one night, that's when this problem started. Leaves appeared to be slightly faded at that time though.

GBAUTO said:
200ppm is pretty weak, especially for Flora.
They look hungry-increase the nute mix.
Click to expand...
Guides I've read for autoflowers said to use 1/2 strength for nutes, or around 150-250ppm. w/ GH's chart, it suggests 2.5ml/gal of each part. I'm using 10ml at 10gal, so 40% strength. Should I bump that up by another 2.5ml ea to 50%? Higher?

Thanks!!
 
70's natureboy

70's natureboy

Well-Known Member
Baby plants like that just love flourescent light. It's a bummer when they have to settle for something else. I think your nutes are a little light. I actually use 3 ml/gal of GH 3 part when they are that small.
 
1Ruby

1Ruby

Well-Known Member
Use a 50-50 mix of distilled and tap water. 9 gals of Distilled water and 1 gal of tap is to pure.
 
G

GTConsulting

Member
increased from 40 to to 50% str, turned lights down to minimum, and raised lights. Doesn’t look like light burn since the newer leaves look fine. From all the pics I’ve seen, light burn will affect the top leaves first but my issue is affecting the bottom first.

Feels like it’s not getting enough nutes, but I don’t have enough experience to know.
 
redi jedi

redi jedi

Well-Known Member
I agree that your water level is too high and your nutes are too weak. Roots will take a long time to develop if the root zone is too wet. I hate rockwool for this reason.
 
G

GTConsulting

Member
myke said:
Light is too close,@10" even at 25%.Put it at 30"
Click to expand...
Turned lights down and raised them. Looks like i decreased lights too much. They’re reaching for more just a few hrs later.
Going to try this Korona ppfd app and adjust to 200ppfd.

Used that app and it showed i may have moved the lights up too much. Moved lights slightly 1-2” to hit 200ppfd at the top of the leaves.
Checked roots and larger place is showing more root growth and smaller one has one root and poking through now. Leaving water at the same level but may move it down tonight. The bottom yellowing leaves still concern me though.
 

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70's natureboy

70's natureboy

Well-Known Member
You are feeding at 1 ml/gal of each part, that is too light. Like I said, I start with 3 ml/gal of each on my newly rooted clones. You also need cal mag with your 90% distilled water. easy fixes.
 
G

GTConsulting

Member
70's natureboy said:
You are feeding at 1 ml/gal of each part, that is too light. Like I said, I start with 3 ml/gal of each on my newly rooted clones. You also need cal mag with your 90% distilled water. easy fixes.
Click to expand...
Can I just use an equal mix of sterilized tap and distilled or just all tap and skip calmag? Girls are doing much better now though.

Bumped nutes 18.5ml/10gal last night (325ppm) and will add 6.5ml more tonight to be on track with this suggested schedule since many said GH's published schedule is too strong and these autoflowers use lighter nutes. Lots of root tips are starting to poke through the netpot so I lowered the water back down yesterday.

Regarding the nute strength, this schedule I'm using calls for 1.25ml and 2.5ml/gal first two weeks. You're suggesting 3ml? I'm really concerned about pushing the nute solution too hot since I've read a lot saying autoflowers need lighter nutes. The breeder even stated 250 max for seedlings and 3-400 for veg start. What I do to increase nute mix is to pull out ~1qt of solution, mix the additional nutes in the pulled quart, and then stir in the concentrate into my res while the pump is off before starting the recirculation again.

Recirculating-Nutrient-Schedule-custom.jpg
 

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1Ruby

1Ruby

Well-Known Member
GTConsulting said:
Can I just use an equal mix of sterilized tap and distilled or just all tap and skip calmag?
Click to expand...
Drop the Distilled water for sure, Distilled water is to dam pure, It's a waste of money. Or no more then a 50-50 mix. And you don't need to sterilize your Tap water, I use it out of the Tap as is, Mine comes out of the Tap at 215ppm. I deduct that from my solution PPM reading when I check it. The plant's will tell you if they need Calcium. Some strains will need or want more then others, So I would keep a small bottle on hand, I also keep some Epson salt on hand as the same applies for Manganese, Each strain or plant will tell you what it needs. Run Lots of AIR to keep your roots healthy I use a 4 inch round flat puck in each bucket with a Strong air pump you can't have to much oxygen!! { Your roots have finally reached the nutrient water, So they will take right -off now, keep your ph in range and You should be Golden just follow the program} Here's a chart that's easy to use download it or even better have one printed out and hang it on your wall for future refence. I run the GH Maxi series the powder and it works a treat!! 50-50 of each Maxi-grow & Maxi-bloom in Veg, Then just Maxi Bloom when I flip the lights to 12-12 It all has Cal-mag in it Just PH it and run. I refuse to pay for liquid nutrients that are mainly just water. So If you ever use the Maxi-series it Just Keep It Dry as in keeping the zipper on the bag closed and sealed. But run what you like. I'm sure others will chime in with what works for them as well. Cheers!!!!!!!!!


https://sites.google.com/site/autofloweculture/home/deficiencies-and-excess-nutrients-charts scroll down tap to enlarge
 
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70's natureboy

70's natureboy

Well-Known Member
You are using 1ml, I use 3 ml, 1/2 teaspoon is 2.5 ml/gal. You are in the ballpark and they should adapt. RO/distilled water is kinda tricky, your schedule tells you how much cal mag is recommended. You should go with that. My tap water is about .2ec and seems to work fine for me. If you question your tap water it may be worth getting it tested.
 
Wastei

Wastei

Well-Known Member
1Ruby said:
Drop the Distilled water for sure, Distilled water is to dam pure, It's a waste of money. Or no more then a 50-50 mix. And you don't need to sterilize your Tap water, I use it out of the Tap as is, Mine comes out of the Tap at 215ppm. I deduct that from my solution PPM reading when I check it. The plant's will tell you if they need Calcium. Some strains will need or want more then others, So I would keep a small bottle on hand, I also keep some Epson salt on hand as the same applies for Manganese, Each strain or plant will tell you what it needs. Run Lots of AIR to keep your roots healthy I use a 4 inch round flat puck in each bucket with a Strong air pump you can't have to much oxygen!! { Your roots have finally reached the nutrient water, So they will take right -off now, keep your ph in range and You should be Golden just follow the program} Here's a chart that's easy to use download it or even better have one printed out and hang it on your wall for future refence. I run the GH Maxi series the powder and it works a treat!! 50-50 of each Maxi-grow & Maxi-bloom in Veg, Then just Maxi Bloom when I flip the lights to 12-12 It all has Cal-mag in it Just PH it and run. I refuse to pay for liquid nutrients that are mainly just water. So If you ever use the Maxi-series it Just Keep It Dry as in keeping the zipper on the bag closed and sealed. But run what you like. I'm sure others will chime in with what works for them as well. Cheers!!!!!!!!!


https://sites.google.com/site/autofloweculture/home/deficiencies-and-excess-nutrients-charts scroll down tap to enlarge
Click to expand...
1. A complete plant food is all that is needed to grow A+ Cannabis.

2. You don't need "calmag" in hydroponics. Almost every two part nutrient line has Calcium nitrate in it listed as first ingredient. You don't even need "Calmag" with RO water in hydroponics.

3. RO or distilled will always be superior to tap or well water. In hydroponics that is.

4. Keeping things sterile is in many ways superior to alive systems running organics. No chiller needed, also the best as a preventative measure for root rot.

5. Don't follow manufacturers nutrient charts or guidelines. Go by plant requirements and aim for as low EC/ppm value as possible.

6. You don't need much aeration to saturate water with DO. Running to much aeration can be counter productive in DWC. You want a homogenous environment.
To much water splashing/evaporating will result in different environments at different water levels instead of being homogenous at all levels.
 
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70's natureboy

70's natureboy

Well-Known Member
None of my nutes will stay PH stable in RO water without calmag. I don't add calmag for the nutes I add it to RO just to stabilize the PH. I tried the "superior" RO water, didn't see any major benefits, I'm not sold so I went back to tap water. It never hurts to experiment.
 
G

GTConsulting

Member
My pH has stayed stable since I switched to mostly distilled. I'm just having what I hope is some algae from light leaks, but I addressed that and plan to do a full res change this weekend. Roots are taking off now, and are still nice and white (except for some non-slimy stuff floating around which I hope is algae and not bacteria. I've been keeping up w/ the H2O2 but will switch to chlorination after the res change.

I have minimal air stones, as I run a recirculating system with a waterfall in the growbuckets. My (hopefully) algae problem didn't start until after I dropping in these small air stones (which I soaked in bleach for an hr before use). But that issue is in another thread. The girls appear to be fine right now. Thanks for all the help and info!
 
Wastei

Wastei

Well-Known Member
70's natureboy said:
None of my nutes will stay PH stable in RO water without calmag. I don't add calmag for the nutes I add it to RO just to stabilize the PH. I tried the "superior" RO water, didn't see any major benefits, I'm not sold so I went back to tap water. It never hurts to experiment.
Click to expand...
There's so many ways to the finish line. That's what so interesting about growing Cannabis. I prefer and has always used potassium silicate to stabilise pH.

I'm biased though because that's what I've always used and it has been working for me all these years. Cheers!
 
kratosxxl

kratosxxl

Well-Known Member
Wastei said:
1. A complete plant food is all that is needed to grow A+ Cannabis.

2. You don't need "calmag" in hydroponics. Almost every two part nutrient line has Calcium nitrate in it listed as first ingredient. You don't even need "Calmag" with RO water in hydroponics.

3. RO or distilled will always be superior to tap or well water. In hydroponics that is.

4. Keeping things sterile is in many ways superior to alive systems running organics. No chiller needed, also the best as a preventative measure for root rot.

5. Don't follow manufacturers nutrient charts or guidelines. Go by plant requirements and aim for as low EC/ppm value as possible.

6. You don't need much aeration to saturate water with DO. Running to much aeration can be counter productive in DWC. You want a homogenous environment.
To much water splashing/evaporating will result in different environments at different water levels instead of being homogenous at all levels.
Click to expand...
Not sure what makes u think he dont need cal mag but you do especially with RO water , besides if you add 1 ml per gall calmag it def wont hurt plants but might help,
I would not add h2o2 at all, if you want sterile add uc roots (or make you own search here how to dilute bleach)
Also when bottom leaves start to yellow first its usually calmag def , happened to me a lot and i was using 3 stage filtered tap.
Also chiller is not a bleach/beneficial replacement nor the other way around. i have chiller and water temp is at 65 and still had algae, so combination of both are the best also it is more of preference if sterile is better i dont think u can suggest that.
You DO follow manuf recommendations but at lower dosage like start of wiht 50 % and raise or lower based on how plants react i dotn know anyone in the world who can look at the plants and say hmm i need 2 ml more of bloom.
Also submerged roots need oxygen cuz higher the res temp less oxygene is available , nothing is wrong with using airstones.
So basically only point 1 make sense the rest not really
 
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