Hello, so i guess i will just try to keep lower temperature, good that those hot days are gone now. I'm using LED lights so i think it's because of the pink light it gives, but i'll check next time possible. If the stems are purple/red isn't it due to the temperature amplitude ? IF not what should i do to help them ? or do you mean that they are getting to much nutrients ? or the water that they are getting is bad ? http://forums.strainhunters.com/topic/8348-skywalker-kush-in-dwc-under-led/page-2#entry128095 I have seen simillar issue with the reds stems on DNA genetics with a LED setup so i think it may be simillar situation to what 'Thusweedman' has ?

hello i would really appreciate some advice, anyone here could say anything about those leafs ? here is a better picture of the half of the box with all 6 plants. Next time i will have an oppurtunity I will take more pictures of the whole room. Thanks again for any feedback with regards Gouda

So I will attach some photos in which you can see that something is a little wrong with the plant. The leaf tips are rolling up - i'm pretty sure it's beacause the heat it was unbearable couple last days outside so it was hard to keep the box cooled. As i had put and additional exhaust fan with a carbon filter on it the temperature had dropped to around 28 celsius previoslu it was around 30 even 31-32 degrees. More than about the rolled up tips i'm worrying about those wrinkled spots that had appeard last time i checked the plants, on one of those pics i underlined the spot that i;m talking about. Plants age : around 20 days from germinating - used coco pellets after the sprouts showed Soił : coco 80% and perlite 20%. Temperature : Day around 30 at first 2 weeks now around 28 (i know it was to high) Night : around 23 Watering : With powedr feeding every 3 day more or less i try to see when they are dry. Around a liter per plant today, earlier less. PH : around 5,5-6. Humidity : around 70% sometimes higher, most of the time a litlle bit lower. Light power : diamond serires xml 350 x 2 height from plants : at begining 75 cenitimeters now around 65. This is what the manufacturer wrote on the description. Size of the room : 2,4 lenght x 1,2 width x 2,4 height (meters) Venitilation : 2 exhaust fans witg carbon filters : around 450m3/h and one fan that is getting air in the box 100m3/h it has a pipe to take the air from outisde the building. I'm using DNA genetics seeds - 6 plants of purple og#18 and im using powder feeding mostly indica for it. It is 70%indica 30% sativa. Other 6 plants are Lemon og kush which are 60% indica 40% sativa and i'm using the powder feeding hybrid for it. Would be really happy if anyone would have any suggestions how to brings those back to health. with greetings Gouda

Thanks a lot, so i will stick with the citric acid then. Oh yeah people are crazy about the 24 hours of air i heard/read about that a lot. I used to do the same thing, but now i thought of the Brita filter. After what You posted i think i will stick just to lowering the PH to around 6 (dont have an PH measuring electric thing) and maybe when something will start looking not too good i will clear my water before watering. So another question anybody here used a water filter at any time ? and could post an answer about the results - i would really appreciate it. Ohhhh and can i ad the PH lowering things ( ph-,citric acid, vinegar) with powder feeding or mixing those 2 is a no no ? (by the way love the simplicty of PF and results it gives) I know that they lower ph by them selfs but when i cheked it today it wasn't enough for coco. I'm using hybrids pack and a shortflowering one. Actually a lot of good opinions on vinegar on diffrent forums as PH doesn't go up with time as with citric acid. Still don't understand when and why it comes back up after a while though ? is it only when we leave the water solution in an opened container or even after watering, after some time the PH of medium is coming back? or is it the same with the proffesional PH- solutions and i should not get bothered by such stuff? With regards Gouda

Has anyone tried to use vinegar or citric acid instead of those proffesional ph- solutions ? From what i read the proffesional solutions can actually be worst than the natural methods. Other people say that even if you use any of those the water after 24-48 h will bring the ph back up. I guess people need this water for big hydro set ups that's why it has to be used for at least 24 hours in a row. Otherwise if coco or soil it's the time to get the chlorine out of the system with which we want to water the plant. So my question is that when i'll be using a Brita filter to get rid of chlorine in a short time and quick after that i will lower the PH of the water for the plants with vinegar or citric acid and then i will water the plants i keep the PH stable ? or even if the water + vinegar solution will have good PH level, some time after puring it into coco the PH of coco will come up beacuse the vinegar/ citric acid will putrefy ? With regards Gouda.

Hello Thusweedman, really nice pic ! I was really happy when i ran through this topic because I'm just about to start some Lemon og kush and some purple og#18 from dna and i'm also using the powder feeding hybrids for the lemon and mostly indica for the purple. My question is what is the model and the power of the Lamp that you are using ? Thanks with regards Gouda.

Number of HID lights add 5% per air cooled light (I use this to calculate LED) Thanks very much for your reply it really helped, i'v been reading about diffrent calculations, this seems to be pretty good with a diffrent approach - in the article i was reading they were multiplying the Watts of the lamp by 0,6 in gardens bigger than 5m3 and the result was just to high - I would have to spend 250euros on a vent . Do you think this calculation for led as the same as HID is accurate ? Are you maybe using Led lamps in your set up ? Thanks anyway very much for your time. Yesterday i was testing the lamps with no vemntilation in the box and the heat was building up but i think it's mainly because the lack of ventilation + high temperature of the air as it is summer. The amount of heat that the lamps produce is actually similar to HPS with a cool tube and a powerfull fan on it. So to sum up i think that the calculation for an HID air cooled lamp is going to be quite simmilar to the Led lamp and it will be optimal for such a grow space. Those are jus assumptions so if i will get going soon with my project I will post the results in temperature as I check it. Thanks again with regards Gouda.

Also i have just read about the Vapor pressure deficit and i was wondering if anyone has some tips how to controll it with Led lamps ? How does changing air in the box effect the VPS ? and if i am going to moisten the air with a humidifier should ventilataion be bigger so the water won't saturate the air ?

Hi I'm new to the forum. I'm from Poland it's really nice to meet all of you guys ! I'm here to get some knowledge about growing the plant I love ! This forum is the best from what i heard and i was reading some topics for a while before registering. Regards Gouda.

Hello, I'm thinking about setting up a growroom in which i will put 2 Led lamps which generate way less heat than the HPS do. What i know is that the air circulation in the box should be at the point of 20-30 times per hour. I have read some articles about the maths you need to do to calculate how much air flow from the vents you should have in your box but this calculations are specified for HPS lamps that generate more heat. If my temperature is around 26-28 celsius deegres should i still ventilate the box at least 20-30 times per hour or does that imply only when HPS lamps are used ? From what i read i can't define if the air exchanging is important only because of the heat or also the plants won't grow if not enough is provided. I'm using Co2 tablets in the room so even if the ventilation should be stronger to get more Co2 i think this is already covered. Mostly i'm scared that if i invest in those expensive vents or put couple of those cheaper ones together and get them to work the temparature will drasticlly fall down and it will be hard to get it up. Does anybody here has a Led lamp set up and this kind of a problem ? The box's size is 2,4m x 1,2m x around 2,5m because the height is adjustable. This gives me 7,2 m3 and if i want to have the box propely ventilated my fan that takes the air out of the box should be around (7,2 x 30 = 216) so around 216m3/H ? I would really appreciate any help provided i got really confused with this led growroom ventilation. previously i had a 400W lamp with a cool tube in a smaller box so it was easier to make a working setup with the proper ventilation. With Regards Gouda.