DWC stems and leaves turning purple

today is day 34 of flowering light cycle, they are currently on 10/14
I use foxfarm trio and hydroguard

Strain; Type, Bag seed, or NA - bag seed, strain labeled "Bone
with a description “smells strange, very strong”

Soil in pots, Hydroponic, or Coco? hydro DWC 4 gallon bucket - 3 gallons of water in bucket

System type? DWC

PH of runoff or solution in reservoir? 5.8

What is strength of nutrient mix? EC, or TDS 140 x10

Indoor or Outdoor indoor

Light system, size? two 300 watt LED FS, 8 CFL softwhite

Temps; Day, Night 60-64f concrete room but buckets have a layer of foamcore between bucket and floor. its getting pretty chilly outside here, battling temp will be an issue. I want to get a carbon filter and return the warm exhaust back into the room to battle the cold winter temps.

Humidity; Day, Night 70%

Ventilation system; Yes, No, Size 6" inline with booster fan

AC, Humidifier, De-humidifier, no need

Co2; Yes, No not in use

largest of the buds so far

Roots of plant that appears to have been stunted…only one plant in this bucket

massive purpling of the stems and roots. the small bud at the left is completely purple

more purple on two plant bucket side. one plant bucket turned purple about a week or so ago, the two plant bucket has just started within the past couple of days

roots of the two plant bucket

bud turning red but you can see the purple creeping into the leaves

leaves and branches getting purple, you can see purple lines running up the stem of the plant

here is my soil grow that had PH problems a few weeks ago, looking good now. Purple Haze on the left, Goldleaf on the right. I can see the stems turning purple though…

my grow room, two tents plus a 3x5 T5 screen for vegging.

single plant in bucket had started to turn purple a week or so ago and its seem to have stunted its growth, it just sits there while the two plants in the other bucket are still thriving

30 day vegetative under the T5

soil grown Goldleaf, I can see some purple in the stems

soil purple haze, leaf on the far right is really showing purple

ack! purple, yellow, there is a lot going on here…

serious problems

Things had been going real well for this strain called Bone, at one time the fan leaves were so huge and plentiful that it filled the tent up.

They are on day 34 of flowering about a week or so ago one plant by itself turned purple and has seemed like it stopped growing or budding. There are two plants in a 2nd bucket in the same tent that over the weekend have started to show signs of purple stems and leaves.

Your numbers don’t make sense.

Are you sure your canopy air temps are 60-64 day and night? And same for your humidity?

Even if inside the house with air conditioning, the lights in the tent will make some heat, there should be a somewhat more significant difference between light on and off temps as well as a change in humidity, colder air holds less moisture, and the plant will transpire less with the lights out.

Also the temperatures in the reservoir could be important. And the temperatures in general would seem most likely to be the cause of the purpling in the stems of all plants and maybe a even bigger factor in the "Bone"strain.

Your roots look white, so they are probably fine, unless they are getting too cold, but the reservoir would have to get a good deal lower than 60F to normally make a huge difference in stunting growth, the reservoir temps are best between about above 60F to maybe just slightly above 70F, and air temps are best between about 70F and 80F. Split the difference and you could say reservoir temps are best about 65F and air temps are best about 75F.

If the air temps are getting much below 60F, but more like below 50F you will get purple bud, all bud will pretty much turn purple with these conditions.

However some strains do show purple even without the cold temps. Your pH is good otherwise I might suspect a nutrient deficiency.Almost any of the macro nutrients can contribute to purple, but often a lack of magnesium is the cause of it in the stems, just some food for thought, you might have no deficiencies, and I’m really thinking especially in the “bones” strain, much of this is specifically due to the strain’s genetics.


Also I don’t use foxfarm and don’t really know anything about it, but I assume it should be decent and have most everything nutrient wise covered and you shouldn’t be having any deficiencies with it in DWC and a 5.8 pH. But anyone with more familiarity with foxfarm and any extra need it might have in DWC are of course welcome.

Also I assume you are practicing good reservoir maintenance and making a complete reservoir change out no later than about every two weeks.

I also assume you do have good aeration and the air pumps were only off when the picture was taken.


Air pumps are on just fine, small bubbles. The temperature has shown min 58f and Max 66f at canopy and water temps have been pretty steady at 58-60f. There is no heat in the room and the exhaust vents the warm air outside.

I have found the plants going through water fast enough that I have not done a water change as I am adding a gallon about every other day. I have wondered if I should take the bucket out for cleaning.

exhaust is your issue get carbon filter and vent air back into room what I see happening is the cold getting pulled out of the concrete floor. The temps never rise because your fan is venting all the heat to fast concrete much like soil at certain depth will maintain an almost constant temp. I live in the north so we actually put radiant heat in our new shop floor the temp coming out of the boiler is around 95f the slab is still in low 30’s after 3 weeks running will take month to absorb enough heat to be effecttive mind you it would take almost as long to cool too.
I grow in Canada 9-16f overnight outside also in a basement concrete floor to keep some of the heat from my lights I vent the tent and veg room into the larger room they are in using a 6" T duct with a damper I redirect some warm air back into room outside tent and veg room after charcoal of course. This maintains a negative air pressure in both tent and veg area while allowing me to control how much return air comes back into room the damper is handy and adjustable and they actually do sell thermostatic dampers if I wished to be lazy.
Hope some of this helps


Yes, not doing a complete change out can be causing nutrient problems. Just because you are replacing water fast doesn’t mean you shouldn’t dump the entire reservoir and start fresh about every two to three weeks depending on the size of your reservoir. I don’t see any undercurrent or recirculating, so the reservoirs should be changed completely about every two weeks.

Your temperature ranges seem a little low, but not so low that they are likely the main cause of the problems, as I said above you can kind of say 65F for the reservoir is almost about ideal, and much below 62 or above 72* is when you might have problems. Much below 60* and absolutely the uptake of nutrients and the biological activity will greatly slow. So 58-60 is a bit too cold. And again air temps are also low, but usually you won’t be having too many problems unless they dip below 50*F for a significant amount of time for the canopy.

Most likely it is the lack of changing out the nutrients completely, this is probably the main contributor. The water looks very cloudy and this is a sign it should be changed. Not only that, not all the nutrients are necessarily used up evenly, if you just add and top off, you really have no idea what the actual NPK ratios or remaining secondary and micro-nutrients are actually at, this can obviously cause you to end up with a reservoir solution that might have nutrient levels that would indeed cause deficiencies or toxicities. A complete change, not that different than a soil flush, ensures these toxic build ups do not occur.

Happy growing,


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The Fox farm flowering feed turns the water grey/cloudy.

I will do complete water change and cleaning tonight and start fresh.

wow. I have certainly learned my lesson.

I did the water change tonight. It really seems like a two person job when the plant is in a net. I did get the bucket out and slowly started pouring out the water. I could see towards the bottom a layer of silty, gray gunk which most likely is settled Fox Farm Big Bloom. What was also probably a major contributor to the overall problem is that the air stone in that tank is a small 4" stone at the end of a hose. As the roots grew out, they grew around the stone and had completely enveloped the stone so the plant was mainling the oxygen but probably wasn’t getting enough, stunting the plant growth a few weeks ago as I had noticed.

This problem now could have been totally avoided had I followed posts about changing your water and cleaning your bucket, stone, etc every two weeks. I am running the plants in clean, plain water with a pH of 5.8 and added 6 ml of Hydroguard for the 3 gallons of water. I will run the clean water for a few days and then slowly add nutes but will pay special attention to their complete mixing with the water in the bucket before putting the lid back on and leaving it.

At least it isn’t a total loss, I should be able to recover somewhat from it but certainly have learned a newbie lesson.

While cleaning the water out, I had my hands in it and damn, that water is cold and we still haven’t hit the cold days yet. the min/max of the thermometer was a low of 52 and a high of 68, that’s too cold and not warm enough. is there any problem with putting an aquarium heater into the bucket and setting it for 72 and then feel safe as the cold weather comes upon us?

As always, many thanks to the Green Gurus, I am grateful for the knowledge you pass on to all of us.

I’d set reservoir water temps as close to about 68F-70F, 72*F is ok, but the 68-70 range is even better.


Understood. However, considering the low temperatures to come, would it be safe to set the water at 72 so that by extension, the plant above the water is kept warmer against the cold?

While I have your attention, here is a lighting question with my tents. I have an array of softwhite CFLs going as well as two 300 watt LED FS lamps, its a 2x3x5 tent so I have an LED on each side of the tent and the CFL in the middle.

I will admit I am a man on a budget and with the winter here, utility bills are rising and since I have only been at this new hobby a few months, the utility bill has taken a decent hit to it. So right now its advantageous that I am in flowering cycle at 10/14 but what I was wondering was what might be an effect if I were to put the two LED lamps on separate timers so they alternate on/off so that only one lamp is on at a time, cutting my overall utility footprint for each tent in half.

I am looking at setting up DWC just for 2 plants but using 3 buckets the reason for third bucket is so I can simply move net pot to new clean bucket pre setup ready to roll. In theory this would let me move 1 plant easily to clean healthy home and water freeing it’s old pot to be cleaned for my other plant to move into staying away from recirc first time around for ease of movement and freedom to experiment any thoughts?

just my two cents worth … get a cheap digital thermometer that records both high and low temps every 24 hr’s … it looks like low temps , and this can cause lock out or up take problems of nutes … i once grew a strain romulan . pretty green, then i shift it to a 10 degree temp drop at nite . and it changed colors ,purple.lime, pale yellow very pretty … but if no drop in room temp no color change . taste or potency didn’t change… just the eye candy… mearsure res temp . may be a fish tank heater or a propagation mat if low temps detected.

I have similar purple problem. Older lower Purple leaves, new leaves are yellow with purple edges, have leave curl and clawing. growing in coir with pH of coir matrix at about 6.5 (i cannot get it lower), My water and nutrient mix I pH to 5.7±, first thought it was nitrogen toxicity with dark green leaves and clawing, then went yellow purple on me. I have flushed, tried correcting for P deficiency etc. Thought it was over watering contributing but the coir dries out fast. I am at a loss. Help!

sorry but I cant be of help here. my grow was hydro and I found out I was using the nutes wrong.

sounds like you got a problem, I hope one of the grow gurus can help you.

Have you been adding a Cal-mag supplement? coco is notorious for Mag issues? Did you wash the coco before using? How often are you feeding and is this hand watered or Hydro setup?

Hope this helps