Am I about to fight root rot again?

Hi folks... am starting to get really dumbfounded.

I started this plant on bennies. Despite good temps, roots started to rot. So I swapped to silver bullet roots, chopped the dying roots and the plant bounced back well, chucking out a tonne of new roots.

I've prepped the plant for a manifold. I realised after removing all that foliage that the ppm was higher than needed (rich red stems, severe leaf curling), so I made a new solution at 400ppm (RO water starts at 1.01ppm). Removed the leaves that were toast, leaving me with a very naked manifold. Looked in the tent this morning to find that the roots were starting to clump together and I had to pull a little slime from the base on the clumping roots. I added another few ml of silver bullet roots to be on the safe side, but I don't understand what's going wrong. As you can see I've eliminated all possible light leaks, even foiling over the top of my hydroton.

As you can see from the photos I have a proper rolling boil going, with a 10" disc air stone sat directly under the net pot, driven by a 25w pump. Res temps - as soon as they hit 19.9c I add an ice block, taking it back to 18.5c. If it were just the roots in the water taking on a darker tone I wouldn't worry - my CalMag and Flora Micro tend to stain a little. But the roots are starting to discolour where they're not in the water - even inside the net pot.

I'm also confused about pH. I adjust it to 5.5 in the morning and by evening it's back to 6.0. So, half a point in 12 hours. It then takes 2 days to rise from 6.0 to 6.2... and this happens every time I drop pH to 5.5. The res seems to want to sit at 6.0 and I'm wondering if the recycled plastic the tote is made from might be causing issues?

I've also added a screengrab of my nute calculator. I'm absolutely methodical in getting my NPK properly balanced and I don't think 400ppm is overfeeding at this stage!?

I'm at a loss - reached the limits of my knowledge. If anyone can tell me what I'm doing wrong I'd be eternally grateful.

Thank you

EDIT: For clarity, I have a 2.5" gap between nute solution and base of net pot.

Thats a tiny plant for all that.

No need for cal mag or silicon atm. Yes even if you are running r/o. Your base nutes have all those things. Just some plants want more. But that comes much later. Keep it simple. Less is more for the most part.

If your ph likes to sit at 6.0 leave it there. Adding ph down all the time messes up your ratios. 5.8-6.2 works perfect. I find different nutes like to stabilize differently.

Your roots don't look bad. But once you got the pathogens in there you need to do something about it.

May need to clean and sterilize everything. Dip the net pot in some h202 water.

I went sterile after trying to run beanies with ice bottles.

I can easily dilute back to 250ppm if even 400 is too much. I was working on the basis that it had 6 main modes before being chopped back to 3rd node then cleaned up.

Everything else is good with the environment? Temps good?

What light? Distance? Temps? RH?

I would honestly just mix a fresh batch of just the basic nutes. Dont go crazy trying to get the perfect npk.

I assume your using GH trio?

Need somebody with more experience with that stuff to chime in.

I use jacks 321 tap.

Base nutes have no silicon or fulvic (hence gh sell both as separate additives). Fulvic is an excellent chelator of micronutrients, doing a better job of making iron absorbable than the artificial chelating agents used in your basic cal/mag (just as one example). Regen-a-root is soluble potash.

Light is a Mars hydro tsw 2000, set at 60% power 20“ above plant. Rh 60% and constant 26c in the room. Nutes kept perfectly between 18.5c and 19.9c. Strain is legendary OG punch from rqs.

FYI I've now diluted back to 300ppm. All I did was pH the RO water and add enough SB Roots to ensure no h202 deficit

This ain't your first grow i take it? You have done this before and had success?

when you add the ice, how cold does the res temp get?

maybe it's the swing you got going on from 19C down to whatever that the roots don't like?

@Failmore - 3rd attempt at DWC… 2 previous failures.

Failed attempt 1: cheap gear. I bought an eBay ‘oxy pot’. 20l bucket supplied with a 1w pump. The inevitable happened by week 5 (not enough oxygen in root zone). I was using a cheap blurple light too.

I should explain, I’m a chemist by trade, and also a geek. If I get into something, I endeavour to learn all I can to be the best I can be. I started off with Ed Rosenthal and Jorge Cervantes’ books, which were a good start, but didn’t touch hydro much. I then discovered Harvey Smith and listened to all his online lectures. I then discovered manicbotanix site and digested everything from there too.

Failed attempt 2: I went too far in the opposite direction, using a 25w pump in the same 20l bucket! There was a 2” gap below the net pot but the pump splashed so much the hydroton was constantly dripping wet. My cheap TDS/pH meters didn’t help much either. I upgraded to Apera Instruments and found my original TDS meter was under-reporting PPM by around 350… it’s no wonder everything was dark green and curled before the roots went soon after.

This is attempt 3. I bought a more suitably sized 45l tote. I made a hole JUST big enough in the side of the tote to squeeze in a temperature sensor and an 8mm air line. I Teflon sealed around the hole once the air hose and temp sensor were pushed through, to ensure absolutely zero light penetration. I foil insulated all sides of the bucket (as seen in the photos) and bought a light with a proper PPF map available, which I knew would give me 1000 PPFD across the whole tent when it came to flowering time. I know from that map and my current power setting that I’m currently giving the plant exactly 550 ppfd.

My PPM’s were perfect until I hacked down 3 perfectly good nodes to try manifolding. I didn’t adjust my nutrient solution when I did this, which led to deep red stems and curling leaves in only 24 hours. I did a full res change yesterday, leaving at 400ppm. I removed all damaged leaves or leaves with red brittle stems. This left me with only the two top leaves from the 3rd node growth you can see in the original picture.

I ‘thought’ based on the mass of the root structure and the chunky main stem that 400ppm would be a good nutrient level, and I’ve done everything to keep things sterile since the early rot from failing with bennies (Orca). The roots recovered really well with the combination of SB Roots (h202 with added colloidal silver) and regen-a-root. That’s why I left both in even though I was lowering nutrients accordingly.

So, short answer… I’m hot on theory, but very short on practice. I’m not afraid to accept my novice status and am happy to put my hand up when I need help. I further reduced PPMs based on your advice. I’ll avoid silicon and CalMag until later stages now (research seems to suggest 30ppm silicon is a good level for all plant stages up to 3 weeks prior to harvest)… but seriously, I’m happy to accept all the good advice I can get. There’s just so many differing opinions in forum-land that it’s sometimes difficult to know when you’re getting sound advice from good growers or just ‘bro science’ from people who have had one successful grow and think they’re god.

@rkymtnman - currently have 16l in my tank. I hook the ice pack on the opposite end of the bucket to the root zone. It takes around 30 minutes for the temp to drop to 18.5 - the temp sensor is half way between the two, and at about half the depth of the nutrient solution.

sven_lordy said:

currently have 16l in my tank. I hook the ice pack on the opposite end of the bucket to the root zone. It takes around 30 minutes for the temp to drop to 18.5 - the temp sensor is half way between the two, and at about half the depth of the nutrient solution.

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maybe you are introducing some bad stuff on the ice pack itself?

if the res is only getting up to 19C, that's not too bad. 66F. with the silver bullet stuff, it should be able to handle up to low 70sF.

also could be the over-fert too after the manifolding.

has your ppms dropped at all? rising? staying the same?

After every ice pack use, I dry it, use an antibac spray, wipe again then re-freeze. Unless it's picking something up in the freezer? Maybe I should anti-bac after refreezing rather than beforehand?

sven_lordy said:

After every ice pack use, I dry it, use an antibac spray, wipe again then re-freeze. Unless it's picking something up in the freezer? Maybe I should anti-bac after refreezing rather than beforehand?

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if you didn't add the ice pack, how warm would your res get up to?

PPMs stayed constant at 400 for the 24hrs since changing the res, but as @Failmore says, it's such a large body of water for what is currently such a small plant that I'm not sure I'd observe any meaningful fluctuation

rkymtnman said:

if you didn't add the ice pack, how warm would your res get up to?

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Don't know! Been so paranoid about keeping under 20c that I haven't seen where it would end up without the extra effort!

I guess the best advice i could give would be to simplify things. I know all they extra stuff has a purpose. But it just causes issues imo.

Hundreds of harvests csn be found on this site with just base nutes.

My first 3 grows i was doing what your are doing now. I read some stuff. Thought I needed all this stuff. Had nothing but issues.

I tried to do the frozen bottle. Never worked for me cause I worked 12 hour shifts at the time.

Lots of people have had amazing grows in dwc and never had issues with rot. I have no idea how or why their system does not rot while my was awful.

It have found it is impossible to look at what other people do and try to make it work for me. So after a bit you just stop looking at what other people say an do, and instead you think for yourself and decide what works for your situation not theirs.

Imo the easiest simplest way to do dwc is sterile. People will prob disagree with me and that is fine.

I run a 2x4 tray with 2 plants in buckets filled with clay pebbles. I spray water over the pebbles and then collect it back in the bucket.

In my res I add
Base nute
Epsom
Calnit
Pool shock
Drip clean
Phosphoric acid

Plants have never looked better.

Kinda a side note. Imo main lining is kinda a gimmic. Yup it will get you some monster buds eventually. But not worth the extra veg time. Easier ways to fill a tent imo. More for people who just want to do something different and unique.

Sorry for the long post.

I guess what I'm saying is take it back to the basics. Get a solid harvest. And then grow and learn from there.

Failmore said:

Imo the easiest simplest way to do dwc is sterile. People will prob disagree with me and that is fine

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agreed.
although i do use bennies now, i always felt it was easier to just kill everything versus worrying about if the good bacteria outnumbers the bad.

Thank you both for your advice - really appreciated. Only a few hours since I reduced ppms and already I'm seeing some improvement (looking more perky, less like it's gasping for breath). As for the roots... will see what I wake up to tomorrow.

Think I said in the last thread I posted that I just want one decent harvest... I can then do more experimenting after I actually possess a stash. I saw the results of mainlining and thought it looked like a good way to get a lot of top bud with an even canopy and zero larf. If you notice in the above pics, you'll see I've already sprouted another seedling. I vowed if it didn't work on this attempt then it was just going to be GH nutes, RO water, SB roots (for keeping sterile), and some basic LST for that little baby. I reckon that seedling needs 2 weeks before it's ready to enter the res (cotyledons only opened yesterday) - will see which plant looks healthiest at that point and either replace the plant currently in the res or start growing the other one in soil. It can grow in the garden for 8-10 weeks til I've taken this one to some sort of harvest, if it picks up!

For where this plant is currently, I reckon there's probably 4 weeks additional veg time going to be needed vs if I'd just done one topping followed by lots of LST. Yet another lesson learned.

Lst and a net is your best friend for an even canopy. Still a lot of skill involved to get it perfect. But close enough works also.

I got my 2x4 mostly filled. I have not trimmed or chopped any leaves or branches at the moment. I'll trim after they stop stretching.

I have stopped jamming under the net and will allow plant to grow up.

sven_lordy said:

Thank you both for your advice - really appreciated. Only a few hours since I reduced ppms and already I'm seeing some improvement (looking more perky, less like it's gasping for breath). As for the roots... will see what I wake up to tomorrow.

Think I said in the last thread I posted that I just want one decent harvest... I can then do more experimenting after I actually possess a stash. I saw the results of mainlining and thought it looked like a good way to get a lot of top bud with an even canopy and zero larf. If you notice in the above pics, you'll see I've already sprouted another seedling. I vowed if it didn't work on this attempt then it was just going to be GH nutes, RO water, SB roots (for keeping sterile), and some basic LST for that little baby. I reckon that seedling needs 2 weeks before it's ready to enter the res (cotyledons only opened yesterday) - will see which plant looks healthiest at that point and either replace the plant currently in the res or start growing the other one in soil. It can grow in the garden for 8-10 weeks til I've taken this one to some sort of harvest, if it picks up!

For where this plant is currently, I reckon there's probably 4 weeks additional veg time going to be needed vs if I'd just done one topping followed by lots of LST. Yet another lesson learned.

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i wouldn't do any training on your next plant. just let it grow naturally: you never know if the stress you are putting them thru is making them more susceptible to rot.