Hi all, I am first time grower in a grow box and I am experiencing some yellowing on my leaves. The plants are entering 4th week of veg and are 9in tall and very bushy. I have 6 19w full spectrum cfl lights, my ph is 5.8-6.0, temp average is 70 and humidity is 50%. I am using GH flora series nutrients. I am not sure of the ppm thing, mine is 210 and I read it should be 600-800 by now. Does this mean there are not enough nutrients? The stems of the plants are also green/purple, Is this normal or problem? I am not sure of the strain, Half of the plants are from a grower friend from Cali and the others are ones I had in a jar in my closet all germinated and have grown very well except for the yellowing and some cupping on a couple of leaves. Also can the large fan leaves be cut off to let more light on the pother plants? I need all the help I can get as I look at 4 different sites and get varying answers. Some say deficiency others say toxicity. Thanks for any and all help. Smitty
Yes it could be you are not giving enough nutrients. Once the leaves are damaged, the leaves won’t necessarily come back. Other new growth should look healthy if the plant is recovering. Purple on the stems is often a sign of nutrient deficiency, usually a sign of over watering. In DWC this could be form the temperature of the reservoir getting too high, it needs to be 75F or lower, ideally around 70F and well above 60*F or not enough aeration. Most likely a magnesium deficiency, this may be remedied by a Calcium magnesium supplement like Calimagic or CalMag plus or epsom salts. PPM needs to be a minimum of about 600 ppm of actual balanced nutrients. And others will tell you much higher, usually the overall ppm would be around 1000 to 1200 ppm.
For the most part, by the pictures alone, the plant doesn’t look that unhealthy. Some of the large fan leaves can be pruned, don’t over do it, only remove it if it is significantly blocking light from other parts of the plant/s that you want to develop. Also severely damaged leaves can be removed without losing too much productivity, don’t forget the leaves are like the solar panels powering the plant.
The ppm will only go up on its own from evaporation, otherwise to get it to go up you need to add nutrients. You can have the ppm go down without doing really anything because the plant is consuming the nutrients, this is a good thing and it means you need to add extra nutrients and water to keep the ppm stable. Of course in such a small reservoir you are going to want to completely replace the entire contents with fresh mixed nutrient water about once a week because not all nutrients may be absorbed by the plant equally, so by replacing with fresh nutrients every week you don’t get a imbalanced build up of anything that might result in a toxicity.
Good advice. We will wait and see what happens:)
Hi, Thanks for the advice. I have flushed the plants and the reservoir before and I just did it today again because I did it the other day and it seems to have gotten worse. When I change the reservoir water, I let the plants drink just PH adjusted water for a day and it lowers the reservoir, they drink a lot. When I put in new nutrients it slows down. I don’t know if the nutrients I purchased off ebay are any good. They were sold in 8oz bottles as a kit and it looks like they were put in smaller bottles. I am waiting for new quart bottles to be delivered. Right now I am letting the plants drink ph balanced water before I add new nutrients. They haven’t done real well since they went to GH flora series. I started with moon dust which came with the grow box and later switched to GH flora. I also used Epsom salt to try and help, it doesn’t seem to, maybe its toxicity and not deficiency? I don’t know I am puzzled, I am in this for the long haul and know it will take a bunch of grow to get the hang of it, but I still need help. Thanks again for the advice and I await more, Mike
Stop it! They need ph balanced nutrient water! Not just ph balanced water, you are just asking for deficiencies!
Even in humans, too much water without nutrient and mineral salts can cause problems, that is why athletes use gatorade so they get enough nutrient salts back in their muscles, otherwise you can cramp up bad, in extreme cases too much water can lead to a heart attack, the muscles just don’t have enough salts to have the electrical impulses function correctly. Think what you are doing to your plant’s muscles so to speak, the leaves are the powerhouse of your plant, no wonder why you are getting little freckle like nutrient deficiency marks on the leaves.
Sorry for the rant, but we have been getting a lot of people doing the same thing, in general – out on the net, I think a lot of practices are deeply misunderstood, like flushing with pure water as the example in this case. In hydro, if you over did it with nutrients, one good flush with pure water will remove pretty much all the nutrients. In soil you might need to flush a little more to get out the excess, but even then after you’ve done the required amount you need proper balanced nutes from there on out.
Hi again, I also am having a hard time getting the ppm correct, I am afraid to keep adding nutrients to make the reading correct. I an using a TDS digital meter and do not know if it is working correctly? Thanks, Mike.
Get a new meter ASAP. Otherwise we know nothing and your plant is dead, sorry there is no way around not having accurate information about PPMs and PH, especially in DWC.
Also, do you know the temp the water in the reservoir is at? A few things I noticed, your thick canopy is probably keeping a lot of light from the water and roots but that clear tote needs to be light proofed asap. The quickest easiest way since you are in the middle of growing and paint is not possible, and this alternative is almost just as good, get HVAC type aluminum tape from your dollar store, much cheaper than buying it at a big box store, and cover the entire outside of the clear tote, absolutely no light should be getting to the roots or the nutes if possible. Even the white top will let more light in than should be, all light getting into the reservoir means algae eating the nutes and or roots instead of your roots being undamaged and getting the benefit of the nutrients. and if the water temperature gets above 75*f you are also going to get root rot.
Your roots look pretty healthy all things considered. I would recommend making sure you have a mild nutrient mix since you don’t have a way to know for sure, if your temps are getting too high, actually using almost only water will kinda be a good thing because it allows the water to hold more oxygen, it may be why you are seeing kinda good results from flushing so often and your pure water almost every other day, lol.
Remember I said the purple is often a sign of over-watering, this is how you over water in DWC. I can hear Laewood grumbling, lol, but use half measured nutrients with added epsom salts until you can be sure of your PPM and temperature, keep it dilute, even the epsom salts, so theoretically all the nutrients are available, even if some seem a bit scarce, with some extra magnesium from the epsom salts to counter “over-watering”, this should help keep extra oxygen in the water by keeping it dilute and keep from any over fertilizing burn. Fresh water holds more oxygen than salt water, and either way water holds less at higher temps, by keeping nutrient salts low, it is a little more like fresh water and can counter the higher temp somewhat.
Also why are there no air bubbles in the picture? Did you turn off the airstone’s air pump in the picture?
Hi again, Thank you for the fast info. I don’t know what the temp in the reservoir is but I stay a constant 68 degrees and 51% humidity with the thermometer I have down at the bottom next to the plastic reservoir so I am hoping that the water is not higher. I will get a thermometer just for the reservoir and I have the metallic tape already since I am in construction and will fix the res tub tomorrow. I will also fool around with the ppm meter tomorrow and see if its bad or not. Thanks for all your info, Mike.
The bubbler is working. I have a 9 in circular spider bubbler and I may have unplugged it while I changed the water. Thanks Mike.
Also, your reservoir is really really small. Maybe you shouldn’t be mixing the nutrients in the reservoir at all. Maybe premix the max amount that will fit in the reservoir in another container, then only add water, in a couple of days after your ppms have dropped well below 600 ppm, just mix a new batch and replace, don’t try to bring your ppms back up to max of around 1000 to 1200 ppms. That is the starting PPM of your premix, as the water level drops, add just water, as PPM drops well below 600, just replace the entire volume with fresh mix. Even in a reservoir slightly bigger with a canopy as lush and big as yours, and especially during flower, I see a lot of people put fresh nutes every other day, no trying to top off or add some extra nutes and water to bring it back up. The more vigorous the growth the plant could be using one nutrient much faster than others and only topping off can easily lead to imbalances in such a small reservoir.
Don’t forget the white top too, the tape will work there too, just cut around the netpots, maybe use aluminum foil for now as you might not want to remove the net pots.
Oh and at your air temps your reservoir temp should be fine so you can use full strength nutes as soon as you are sure of your ppms.
And so it looks like it is only the light getting to your reservoir that is making things look so bad, yes that mucky looking stuff is algae making your water look so unclear. I think just changing it out often until you get it light proofed is the best plan of action for now, with pretty much full strength nutrients.
I believe I have found the problem. I have figured out the ppm meter and it is 10 times what it was reading. The plants had way too much nutrients. Without flushing I have the ppm down to 1500 and ph.at 6,2 with the temp at 69 and humidity at 58%. The plants are 11in tall and I am getting ready to go to flowering stage in a couple of days. Is 12/12 light the right combo for flowering after being on 24/7? Thanks Mac for giving me some good advice and a kick in the preverbal ass to get me thinking about all of this. Its not an easy thing to start out new, with no experience and get it right. I know I will encounter some more problems along the way but with help like this it will be great. I have read a few guides/grow bibles and Roberts and Ryan’s are the best, but you still need advice from the experienced growers. The price of medical in NJ is crazy. This is the only way to go.