Struggling with my plants

[Tez420]

Equipment: -5x5 Mars hydro tent
- Mars hydro ts3000
- Vivosun 6” 440 cfm in-line fan
- Vivosun 32 watt air pump
- 1.6 in air stones
- 5 gal bucket(s) wrapped in reflectix
- 6” Netpots
- Taotronics humidifier
- Hydroton
- 1.5” Rockwool cubes
- Apera instruments pc60 combo meter
Nutes: - GH floratrio
- UC roots
- Calimagic
- Rapidstart

First grow. Ive been growing monster gelato and gelato og from seedsman for 5 weeks 4 days now. I’ve been running 2.5 ml of gh trio and 3 ml of uc roots. Ph stays 5.8-6.2. Air temps are 67-73, water temps stay pretty consistent 67/68. The rh ranges from 55% to 60%. Light is on 1

Up until 3 days ago, the grow has been slow but okay. Previously Had some slight root browning, not slimy to touch but discolored, and they got a little leggy during germination. Besides those issues and slow growth, the plants were very green and healthy looking. 3 days ago, (which was the same day I added the first dose of rapid start 3ml, and changed the light off dimmed to 50% hoping to speed up growth) I came home to droopy, still green but very sad, overwatered looking plants. I instantly swapped out my buckets assuming that they were hating the new rapid start I had added in. They keep getting worse. The leaves started to twist and curl up and down on the second day and the third day, they’re turning yellow curling/twisting and looking like they have some sort of deficiency on the leaves. It looks like I’m getting some new white root growth but all 3 plants have stopped growing.

I also want to add in that when I came home initially to the sad plants, we had just had a very bad rainstorm and the humidity was up to like 67%. I’ve also noticed all of the stems and leaf veins turning purple, which I’ve read can be genetics or stress, but I think it’s a little odd that 3 plants show purple veins at the same time while showing the same problems.
I’ve included pictures of how they were looking before the meltdown(the pic with the lights off is the day I noticed them) and then how they progressed.

As u can see my plants doing the loopty loop, ... send help!!! I’d love to see them recover. Thx in advance for going through all this.

 

[Grandma Weedstein]

Equipment: -5x5 Mars hydro tent
- Mars hydro ts3000
- Vivosun 6” 440 cfm in-line fan
- Vivosun 32 watt air pump
- 1.6 in air stones
- 5 gal bucket(s) wrapped in reflectix
- 6” Netpots
- Taotronics humidifier
- Hydroton
- 1.5” Rockwool cubes
- Apera instruments pc60 combo meter
Nutes: - GH floratrio
- UC roots
- Calimagic
- Rapidstart

First grow. Ive been growing monster gelato and gelato og from seedsman for 5 weeks 4 days now. I’ve been running 2.5 ml of gh trio and 3 ml of uc roots. Ph stays 5.8-6.2. Air temps are 67-73, water temps stay pretty consistent 67/68. The rh ranges from 55% to 60%. Light is on 1

Up until 3 days ago, the grow has been slow but okay. Previously Had some slight root browning, not slimy to touch but discolored, and they got a little leggy during germination. Besides those issues and slow growth, the plants were very green and healthy looking. 3 days ago, (which was the same day I added the first dose of rapid start 3ml, and changed the light off dimmed to 50% hoping to speed up growth) I came home to droopy, still green but very sad, overwatered looking plants. I instantly swapped out my buckets assuming that they were hating the new rapid start I had added in. They keep getting worse. The leaves started to twist and curl up and down on the second day and the third day, they’re turning yellow curling/twisting and looking like they have some sort of deficiency on the leaves. It looks like I’m getting some new white root growth but all 3 plants have stopped growing.

I also want to add in that when I came home initially to the sad plants, we had just had a very bad rainstorm and the humidity was up to like 67%. I’ve also noticed all of the stems and leaf veins turning purple, which I’ve read can be genetics or stress, but I think it’s a little odd that 3 plants show purple veins at the same time while showing the same problems.
I’ve included pictures of how they were looking before the meltdown(the pic with the lights off is the day I noticed them) and then how they progressed.

As u can see my plants doing the loopty loop, ... send help!!! I’d love to see them recover. Thx in advance for going through all this.

A lot of people won’t like this, but I say buy some soil, put it into pots and transplant into those containers after cutting away the sickly parts of the roots. All this looks like way too much complication for a first time grow. Plants grow in dirt.

 

[Tez420]

A lot of people won’t like this, but I say buy some soil, put it into pots and transplant into those containers after cutting away the sickly parts of the roots. All this looks like way too much complication for a first time grow. Plants grow in dirt.

I’m growing 4 plants in dirt as well but I really want to get hydro dialed in. If the plant can be saved in hydro that’s my first option.

 

[013]

I’m soil guy but think it may not be enough air space between media and water plus you could benefit from a bacillus bacteria like hydroguard

 

[Grandma Weedstein]

I’m growing 4 plants in dirt as well but I really want to get hydro dialed in. If the plant can be saved in hydro that’s my first option.

I know, I know, only one way to learn and so on. I am not shitting on hydro but you may want to clean your equipment and start with other plants. My guess is these plants have already been destabilized or stunted somehow, so it’s going to be tough to know if you’ve got it dialed in right.

That said, there are folks on here who know a lot about hydro, so maybe they have better advice.

 

[Southerncough]

Yeah, STARTING on dwc is tough...it's like learning to drive...in a formula one car. One tiny wrong move and it's over FAST!
I think the point everyone is making is to get a few cycles in with a more forgiving media where you have more time to adjust and save troubled plants. Learn how to wrangle pests and fix deficiencies. Learn how to train them. Learn what they like and dislike without killing them.
DWC can yield huge under the watch of a skilled grower but like professional drivers they still occasionally crash their cars. Learn the difference between light burn and nutrient burn and how to resolve without having an anxiety attack every day before opening your tent whispering "please don't be dead please don't be dead..."

Not trying to be a downer, I've attempted DWC several times but have only succeeded with basil. Never got a cannabis plant to survive the whole time. It seemed once i bought the thing i needed to fix an issue i had to buy another more expensive thing to fix a new issue, etc etc.
As for your current situation if a DWC acts like it's over watered it means that the roots aren't shipping the goods up north very well. Why?
Not enough oxygen? Bacterial slime? Root rot? All of the above?
From there what are some remedies?
Go nuclear with peroxide? Go Biological send some good bacteria or enzymes in to battle the yucky ones? Go into coco or soil? Scrub the system and raise the oxygen level?

 

[MackMurder]

Equipment: -5x5 Mars hydro tent
- Mars hydro ts3000
- Vivosun 6” 440 cfm in-line fan
- Vivosun 32 watt air pump
- 1.6 in air stones
- 5 gal bucket(s) wrapped in reflectix
- 6” Netpots
- Taotronics humidifier
- Hydroton
- 1.5” Rockwool cubes
- Apera instruments pc60 combo meter
Nutes: - GH floratrio
- UC roots
- Calimagic
- Rapidstart

First grow. Ive been growing monster gelato and gelato og from seedsman for 5 weeks 4 days now. I’ve been running 2.5 ml of gh trio and 3 ml of uc roots. Ph stays 5.8-6.2. Air temps are 67-73, water temps stay pretty consistent 67/68. The rh ranges from 55% to 60%. Light is on 1

Up until 3 days ago, the grow has been slow but okay. Previously Had some slight root browning, not slimy to touch but discolored, and they got a little leggy during germination. Besides those issues and slow growth, the plants were very green and healthy looking. 3 days ago, (which was the same day I added the first dose of rapid start 3ml, and changed the light off dimmed to 50% hoping to speed up growth) I came home to droopy, still green but very sad, overwatered looking plants. I instantly swapped out my buckets assuming that they were hating the new rapid start I had added in. They keep getting worse. The leaves started to twist and curl up and down on the second day and the third day, they’re turning yellow curling/twisting and looking like they have some sort of deficiency on the leaves. It looks like I’m getting some new white root growth but all 3 plants have stopped growing.

I also want to add in that when I came home initially to the sad plants, we had just had a very bad rainstorm and the humidity was up to like 67%. I’ve also noticed all of the stems and leaf veins turning purple, which I’ve read can be genetics or stress, but I think it’s a little odd that 3 plants show purple veins at the same time while showing the same problems.
I’ve included pictures of how they were looking before the meltdown(the pic with the lights off is the day I noticed them) and then how they progressed.

As u can see my plants doing the loopty loop, ... send help!!! I’d love to see them recover. Thx in advance for going through all this.

I've not a hydro grower but ill try some common sense.

1.your roots are unhealthy. Brown and slimy suggest root rot. (Hydrogaurd or cannazym may help the situation in the future)
For the size of those plants those roots are tiny. When my plants are that size in pro mix hp they'll fill a solo cup with roots.

2. unhealthy roots mean their not feeding so the plants are cannibalizing themselves where you see burnt leafs and no chlorophyll.

3. The droopy effect could mean overwatered. Is there not enough oxygen getting to your roots? How far away is the water level to the to the roots? Are those bubblers working well?

4. I get purple veins and stems on some plants.
Some people say its genetics. Some say ph. Some say too cold temps at night. Its a range of what ifs.


Your main problem is your roots.
Me personally. I'd stop adding UC Roots and I'd stop adding the other root thing and just stick to the trio and the calmag and then rhe UC roots. Roots will grow if the plant is healthy. (Cuttings will grow roots in a glass of water without any fancy rooting compounds. )

I would also make a solution of hydrogen peroxide (3% strength that you buy at the pharmacy)
Id then take that and mix 1 part hydrogen peroxide to 3 parts water.

Take your your plant and roots out of the reservoir and wipe they dry. Cut off any extremely brown or slimy roots and then bath your roots in this solution. Hydrogen peroxide has an extra oxygen molecule that will help the roots hopefully. Once you stick the roots in this solution you should little bubbles from the peroxide cleaning your plants roots.

And then just feed them a bit of your three part, calmag and uc roots. Stay away from the other additives for now and once plant is established a bit more roots give that a shot again.

This is just my advice for your situation. Therrs really not a whole lot of other options.
Your plants are going to die if you dont do something for the roots thats just plain and simple..

Also don't trip over humidity too much bruvv. The ONLY time humidity actually matters is when its too high. High humidity leads to white powdery mildew and bud rot.
I grow from seedling to flower in a humidity of about 25% to 45% due to my geographic location. I have 2000 watts (at the wall) of light in a 8x8 tent. To battle the heat when lights are on i have 2x6" that run constantly and 1x6" that runs at night constantly to keep W.P.M and bud rot away. I couldn't run a humidifier if I tried now and it hasn't hurt my plants or my yeilds and ice never worried about raising humidity since.

Everytime your 6" fan kicks on in that little tent your going to exhaust your humidity out. And to keep constant air flow into that tent to provide the 450ppm of fresh atmospheric c02 (i forget what the rule is with CFM) but you gotta be able to exhaust the air in your tent once every 2 or 3 minutes or something to that effect and your lil humidifier will end up being useless. Especially when those 3 plants grow into monsters and start evaporating water out through their leaves.
I went through the same thing. I looked at water misters. Whole house humidifiers. Etc...

And if you wanna grow hydro. Grow hydro. Soil is easier. But its not without its problems. A new grower is a new grower. You have a very nice little setup and it sounds like youve done your homework. You mention water temperature which most new hydro growers wouldn't even think about.
Your just having a little hiccup. Thats fuck all. Roots are roots, plants are plants, and ph is ph.
You'll figure it out.
Keep us posted

 

[Tez420]

Yeah, STARTING on dwc is tough...it's like learning to drive...in a formula one car. One tiny wrong move and it's over FAST!
I think the point everyone is making is to get a few cycles in with a more forgiving media where you have more time to adjust and save troubled plants. Learn how to wrangle pests and fix deficiencies. Learn how to train them. Learn what they like and dislike without killing them.
DWC can yield huge under the watch of a skilled grower but like professional drivers they still occasionally crash their cars. Learn the difference between light burn and nutrient burn and how to resolve without having an anxiety attack every day before opening your tent whispering "please don't be dead please don't be dead..."

Not trying to be a downer, I've attempted DWC several times but have only succeeded with basil. Never got a cannabis plant to survive the whole time. It seemed once i bought the thing i needed to fix an issue i had to buy another more expensive thing to fix a new issue, etc etc.
As for your current situation if a DWC acts like it's over watered it means that the roots aren't shipping the goods up north very well. Why?
Not enough oxygen? Bacterial slime? Root rot? All of the above?
From there what are some remedies?
Go nuclear with peroxide? Go Biological send some good bacteria or enzymes in to battle the yucky ones? Go into coco or soil? Scrub the system and raise the oxygen level?

I have 4 plants growing in dirt that are doing great, I just think hydroponics fascinating as all get out so why not give it a shot! I’m using UC roots which should keep my grow sterile right..? The water is vigorously bubbling so I doubt aerations the problem

 

[013]

I just bought 2 new hydrometers for my garden. Drove 90 miles to the nearest grow shop, came home to find out both devices were off by 8 to 9 degrees. I ran thru a whole 20 pack case to find 2 that registered correctly. Hydro shop guy doubted me at first but he watched as I tried one after another and he could see they were all off by at least 5 degrees on average some as many as 10 degrees off. Point is - Double check your dwc res temps, those cheap ass mini hygrometers like shown in your pics are not reliable. Could be cold feet from buckets on the floor - what kind of floor is under your tent - cause if there’s a tile floor or concrete slab then yup that will do it.

but Mack & Southern Cough gave good advice - hydro is tricky, yes it’s faster but you can hit the wall quicker too. Just in case I’m going to ask @bluter to look at you - guy know his shit for sure

 

[1ne eye]

First off i would get some Hydrogaurd, add about 5ml to buckets each nute change, you should have about 1 to 2 inches of space between your net pot and water. Also in my opinion 2.5 ml is not alot of food ( nutes ). All your temps look good, ro could be a touch high but i don't think thats the problem. Not sure about uc roots but i would swap to hydrogaurd. This is just my thoughts. Im not the sharpest crayon in the box, but i'm the most colorful. Good Luck.

 

[Tez420]

I’m soil guy but think it may not be enough air space between media and water plus you could benefit from a bacillus bacteria like hydroguard

I’m running 6” net pots and 7” of air from the top of the bucket.. looks to be more than an inch of room. I think I’ll swap uc roots for hydro guard, though I’ve heard good things about both.

 

[Tez420]

I know, I know, only one way to learn and so on. I am not shitting on hydro but you may want to clean your equipment and start with other plants. My guess is these plants have already been destabilized or stunted somehow, so it’s going to be tough to know if you’ve got it dialed in right.

That said, there are folks on here who know a lot about hydro, so maybe they have better advice.

What would you recommend sterilizing with? I’ve already accepted these might be stunted but It’s more about the learning curve for me.

 

[Tez420]

I've not a hydro grower but ill try some common sense.

1.your roots are unhealthy. Brown and slimy suggest root rot. (Hydrogaurd or cannazym may help the situation in the future)
For the size of those plants those roots are tiny. When my plants are that size in pro mix hp they'll fill a solo cup with roots.

2. unhealthy roots mean their not feeding so the plants are cannibalizing themselves where you see burnt leafs and no chlorophyll.

3. The droopy effect could mean overwatered. Is there not enough oxygen getting to your roots? How far away is the water level to the to the roots? Are those bubblers working well?

4. I get purple veins and stems on some plants.
Some people say its genetics. Some say ph. Some say too cold temps at night. Its a range of what ifs.


Your main problem is your roots.
Me personally. I'd stop adding UC Roots and I'd stop adding the other root thing and just stick to the trio and the calmag and then rhe UC roots. Roots will grow if the plant is healthy. (Cuttings will grow roots in a glass of water without any fancy rooting compounds. )

I would also make a solution of hydrogen peroxide (3% strength that you buy at the pharmacy)
Id then take that and mix 1 part hydrogen peroxide to 3 parts water.

Take your your plant and roots out of the reservoir and wipe they dry. Cut off any extremely brown or slimy roots and then bath your roots in this solution. Hydrogen peroxide has an extra oxygen molecule that will help the roots hopefully. Once you stick the roots in this solution you should little bubbles from the peroxide cleaning your plants roots.

And then just feed them a bit of your three part, calmag and uc roots. Stay away from the other additives for now and once plant is established a bit more roots give that a shot again.

This is just my advice for your situation. Therrs really not a whole lot of other options.
Your plants are going to die if you dont do something for the roots thats just plain and simple..

Also don't trip over humidity too much bruvv. The ONLY time humidity actually matters is when its too high. High humidity leads to white powdery mildew and bud rot.
I grow from seedling to flower in a humidity of about 25% to 45% due to my geographic location. I have 2000 watts (at the wall) of light in a 8x8 tent. To battle the heat when lights are on i have 2x6" that run constantly and 1x6" that runs at night constantly to keep W.P.M and bud rot away. I couldn't run a humidifier if I tried now and it hasn't hurt my plants or my yeilds and ice never worried about raising humidity since.

Everytime your 6" fan kicks on in that little tent your going to exhaust your humidity out. And to keep constant air flow into that tent to provide the 450ppm of fresh atmospheric c02 (i forget what the rule is with CFM) but you gotta be able to exhaust the air in your tent once every 2 or 3 minutes or something to that effect and your lil humidifier will end up being useless. Especially when those 3 plants grow into monsters and start evaporating water out through their leaves.
I went through the same thing. I looked at water misters. Whole house humidifiers. Etc...

And if you wanna grow hydro. Grow hydro. Soil is easier. But its not without its problems. A new grower is a new grower. You have a very nice little setup and it sounds like youve done your homework. You mention water temperature which most new hydro growers wouldn't even think about.
Your just having a little hiccup. Thats fuck all. Roots are roots, plants are plants, and ph is ph.
You'll figure it out.
Keep us posted

First off thanks for the advice . The roots are brown but not slimy, just clarifying. My air stones bubble up, a lot so I think they’re getting oxygen. My water is 7” down from the top of the bucket leaving what looks like a few inches. I will cut out the rapidstart and just run trio+calmg. How short would you recommend cutting the roots down and how long would you soak the roots in that solution?

 

[Tez420]

I just bought 2 new hydrometers for my garden. Drove 90 miles to the nearest grow shop, came home to find out both devices were off by 8 to 9 degrees. I ran thru a whole 20 pack case to find 2 that registered correctly. Hydro shop guy doubted me at first but he watched as I tried one after another and he could see they were all off by at least 5 degrees on average some as many as 10 degrees off. Point is - Double check your dwc res temps, those cheap ass mini hygrometers like shown in your pics are not reliable. Could be cold feet from buckets on the floor - what kind of floor is under your tent - cause if there’s a tile floor or concrete slab then yup that will do it.

but Mack & Southern Cough gave good advice - hydro is tricky, yes it’s faster but you can hit the wall quicker too. Just in case I’m going to ask @bluter to look at you - guy know his shit for sure

I will double check my water temps... & my buckets are sitting on a concrete basement, I’ll move them up off the floor. Awesome I could use all info I can.

 

[Tez420]

First off i would get some Hydrogaurd, add about 5ml to buckets each nute change, you should have about 1 to 2 inches of space between your net pot and water. Also in my opinion 2.5 ml is not alot of food ( nutes ). All your temps look good, ro could be a touch high but i don't think thats the problem. Not sure about uc roots but i would swap to hydrogaurd. This is just my thoughts. Im not the sharpest crayon in the box, but i'm the most colorful. Good

First off i would get some Hydrogaurd, add about 5ml to buckets each nute change, you should have about 1 to 2 inches of space between your net pot and water. Also in my opinion 2.5 ml is not alot of food ( nutes ). All your temps look good, ro could be a touch high but i don't think thats the problem. Not sure about uc roots but i would swap to hydrogaurd. This is just my thoughts. Im not the sharpest crayon in the box, but i'm the most colorful. Good Luck.

I’ll try hydroguard. There’s a inch or two between the netpot and water. What would you recommend for feed? I’ve been following gh schedule and was planning on moving to more nutes when I noticed the plant growing leaves significantly faster but it’s not.

 

[MackMurder]

I have 4 plants growing in dirt that are doing great, I just think hydroponics fascinating as all get out so why not give it a shot! I’m using UC roots which should keep my grow sterile right..? The water is vigorously bubbling so I doubt aerations the problem

First off thanks for the advice . The roots are brown but not slimy, just clarifying. My air stones bubble up, a lot so I think they’re getting oxygen. My water is 7” down from the top of the bucket leaving what looks like a few inches. I will cut out the rapidstart and just run trio+calmg. How short would you recommend cutting the roots down and how long would you soak the roots in that solution?

Soak the roots until no more bubbling occurs with hydrogen peroxide solution.
The reason I suggested hydrogen peroxide because it will eat at some of the bad shit and also provide immediate oxygen to some of your roots if their healthy because hydrogen peroxide is essentially oxygen.

BUT you have to sterlizie your entire system as well and all equipment too eliminate the source of the problem.
You would probably have to run a bleach solution of some sort (find the recipe online) and run thst through your hydroponic system for minimum 12 hours

The guide i linked below from "growweedeasydotcom" recommends fixing your problem with hydrogaurd not peroxide (because most people just wash roots with peroxide and don't clean their whole system) and I wouldn't argue with that. Peroxide isn't gonna hurt and will help a but if they say hydrogaurd will work better then by all means use that


Root rot is a pathogen. And there's many forms of it.
That DC roots says its a descaler used to prevent rootrot and has bleach in it or chlorine from reading the label.

Hydro gaurd and voodoo juice is a natural product which has good bacteria has bacillus which attacks the pathogen and feeds off dead organic matter and turns it into food for your roots and keeps your roots healthy.

UC roots looks like a root rot preventer. But since it didn't prevent. I'd personally try hydrogaurd.

They might not be slimy yet but brown roots is root rot or some form of it.
If their extremely affected you should be able to pull off each infected root easily with your fingers.

There's lots of info and grow guides on Google for treating and preventing root rot.

Hydroponics Root Rot: What You Should Know - Farming Aquaponics

Root rot in a hydroponics garden can be a problem that goes from bad to worse. We'll show you how to diagnose and treat Hydroponics root rot.

farmingaquaponics.com

Cannabis Root Rot - How to Identify & Get Rid of It Quickly!

Discover how to finally beat root rot (brown or slimy roots) for good! The secret to curing and prevention is a supplement with a particular type of bacteria!

www.growweedeasy.com

And as a side note if u have problems with water temps in a little system like that a frozen water bottle will easily work to keep reservoir temps down. Pathogens like warmer water and your roots feed off oxygen easier with colder temps

 

[Southerncough]

fyi, I use some cheap aquarium thermometers with the suction cup to monitor my water temps

 

[013]

Yup if your tent sits on an indoor or covered concrete slab like in basement or garage then the slab stays at 55 degrees all year long...cold feet will slow a plant down

 

[Grandma Weedstein]

What would you recommend sterilizing with? I’ve already accepted these might be stunted but It’s more about the learning curve for me.

Having never sterilized roots, I don’t know. But I had a plant that got rootbound and started looking shitty, so I just took a saw and cut the rootball down to like 2/5 of original size. Seems to be regenerating well. Maybe cut off the roots that look shitty while leaving enough to regenerate.

 

[TegridyGrower]

What would you recommend sterilizing with? I’ve already accepted these might be stunted but It’s more about the learning curve for me.

I have used a 150 ppm active chlorine mix in coco when I had problems; it seemed to be successful, but I'm not 100% sure.

A while ago, in the early stage of my current grow on coco, I was struggling with constantly droopy plants for a few weeks and at one point it started to look really bad. Also necrosis on the leaves appeared and growth slowed down completely. Panic off course, mainly because all environmental factors seemed to be in check. At that point, I was certain the problem originated in the rootzone.

The pots were standing in plant saucers. I always removed runoff water from the saucers, but off course, the pots keep dripping out for a while and fill the saucer up a bit, long after fertigation. I use airRap pots. The bottom of the pots inside the AirRap pots are a little bit raised (the blue thingy in the picture below), so I was never worried by the tiny layer of water in the saucer. However, the outer plate wrapped around the bottom of the airRap pots forms a shield against air to get under the pot. There’s just I tiny split between the saucer and the wrap of the pots. To clarify:

The yellow edge is standing on the saucer. If there’s water in the saucer under the blue raster, it will be completely still, no air movement and dark. Moreover, due to the lights and the fact that both the pots and the saucers I use are black, I suspect temperature within that space can easily reach 25c, if not higher. I also made the mistake of using a fertigation mix at 22c, which is a little too high.

I believe that this caused problems in my rootzone. When I opened one of the pots, the bottom parts of the roots didn't look healthy at all. Besides that, there was also algae growing on the top of the medium.

I use chlorine tablets to sanitize my tent and equipment between each round of growing. I used national regulation for hospitals in my country to look up which kind of surface disinfectants are for example used to clean surgery rooms. There's a government agency in my country that keeps a list of disinfectants that are permitted to use for certain jobs and they also provide usage instructions. The chlorine tablets I use, result in a mix of 150 ppm active chlorine if dropped into 10L of water. With this mix, surfaces are cleaned. For the removal of blood and other (human) stuff, double strength is needed (so 1 tablet on 5 liters) and to clean out cattle transport wagons, 1 tablet per liter is recommended. You also need to let it work for at least 5 minutes.

So, I decided to flush my 2 plants with 5 liter of 150 ppm active chlorine mix each, in an effort to prevent further spreading of the problems in the rootzone. I pH'ed the water down to 6.8 (our tap water is around 8) before adding the chlorine tablet. This way I’ll prevent a pH spike in the medium, but the water isn’t too acid to react with the chlorine transforming into the dangerous chlorine gas. I used my pressure sprayer for it, so I could make sure that the mix was distributed everywhere in the pot, plus it takes a while to spray 5 liters (hence, the medium gets soaked slowly). I sprayed underneath the pot, to clean the roots poking out the raster. I also sprayed the sides of the pots, a lot of regular used equipment and the bottom of the tent. The plants were completely soaked with the chlorine solution and I let them sit (outside the tent) for about 30 minutes. In the meantime I cleaned the tent and regularly used equipment with plain water, to remove the chlorine.

Subsequently, I flushed the plants thoroughly with plain, pH'd water. However, I also took a bunch of other measures to take away the cause (the pots are now on a raster above the saucers and a small fan is positioned to blow air underneath the pots).

Only 6 hours later the plants perked up and within a few days they completely recovered, regaining fast growth and they didn't droop anymore. However, I'm too inexperienced to conclude with certainty that the chlorine treatment was the fix. I'm actually not even a 100% sure that my diagnosis was correct... Nevertheless, two conclusions are pretty certain to me:
1. The chlorine treatment didn't kill the plants;
2. After treatment, all the algae was gone and never returned. So at least it killed some of the unwanted stuff.

So in short: you can try chlorine at 150 ppm.