So I've got a little 2 by 5 foot tent that I flower 3 or 4 plants in. I'm changing from my current lighting (2x125w red CFLs and 2x100w LED panels) to one 600w HPS with a standard for flowering as I think it'll be far better. However, due to the rectangular nature of my tent I want to know the best way to hang my reflector. I read somewhere that you want the longest side parallel with your shortest tent side... I have no idea why. So which way shall I hang it? I was assuming that I'd do the bulb parallel with the longest side before I read that, but now I'm guessing that it puts out mostly side ways so you want it perpendicular. And so would it be best just to flatten the reflector out to get the best light spread in this shape tent? Thanks!
You want the bulb perpendicular to the longest side of the grow because the ends of the bulbs don't put out light so you have them point where it's not needed.
If you flatten out the reflector then you waste a lot of light hitting the side of the tent and bouncing back at the bulb instead of angled down like the reflector would. I would leave the reflector how it was made and if the tent walls are reflective enough to bounce light back in you'll be fine. When it's all setup, and if you have white walls its easier to notice, you'll see a definite shadow line where the direct light from the bulb dims to the ambient (reflected) light that is just bouncing around the tent. You want that line pretty close to the edge of your canopy, just above it. You'll have to tinker a little bit with light height and plant canopy temperature. If the reflector blocks too much light after you've found the safe temperature and height then go ahead and bend it out a little. I have a 600w in a sealed reflector made for a 1000w, so what happens is I put the light closer to the canopy because the temps are fine, but I miss the edge. Now I run the light a little higher, about 12-18" off the tops, and I put up some reflective material right at the level of that shadow cast by the hood so I'm not wasting any light hitting the walls of the room, and the plants respond to it really well. I also have some extra fluorescent tubes in there for some extra side lighting.
Yeah, now that you point it out it seems pretty obvious that flattening it totally would mean 180 degrees of light... I'll need more like 120 I reckon. It's just that 2 by 5 is a slightly awkward shape to light. I might hang the LEDs either side of the HPS to cover the edges and double up with the HPS in the overlapping areas. Thing is that's 200W more power consumption, I'm not sure whether it will pay off... Might be unnecessary. I know more light is always good though...
More light is good, but more heat isn't. As long as you can take care of heat and the cost of power then go as big as you want. Yeah, a 600W doesn't stretch to 5 feet very well. I'm at about 4 x 6 and I added more light on the long side.
Well the LEDs don't get too hot. I figure if I can handle the 600W HPS then the LEDs will be ok as well... But it's whether I can handle that HPS... I've got a 5 inch exhaust extraction fan that I've turned down to about half power to reduce the annoying noise (no carbon filter and no ducting to reduce suction further) and two oscillating clip fans trained on the plants so that they move in the breeze. Then I've also got two low powered USB desk fans... They're dirt cheap on ebay or amazon, then get a USB plug adapter too. They're great for seedlings and for individual plants up to 10 inches or so, but I thought it'd be good to tape one half way up the tent pole just to push a small breeze directly over the HPS bulb under the reflector. With this fan system I hope to eliminate hot spots at least, but whether that air movement will keep the overall temperature down enough I will only be able to tell once I put it to the test I guess. At the moment with the 2x125W CFLs and 2x100W LEDs I have a small 50W tube garden heater running 24/7 at about half power to keep the tent a little warmer than the lights do on their own. I also run the lights at night to try to balance out heat differences better (and cos of cheaper off-peak electricity). With the 600W HPS I will obviously remove the heater. And possibly turn up the extractor fan. If it gets too loud... Well I could do with a better one anyway... So I'll have to upgrade. Just started 12/12 a week ago. Harvest is probably another 9 weeks away with this PPP. Summer is coming. Attics get hot when it's hot.
Get a thermometer that records high and low. Home depot has a $10 one that does temp and humidity, it resets every 24 hours to when you put the battery in. I have it reset at like 2am so it will record the hottest and coldest parts of the cycle, it's usually around 63-73 now in spring. I notice I'm pulling so much air with a 6 inch Canfan (on full, I don't have a speed controller) that my room never gets above about 73, I'd like it to be about 80 but the weather has been kinda cold here, but as soon as the spring showers stop it'll be 80-90 until sept and I get way more heat to deal with yay! Sounds like you've got it setup pretty well, you'll probably be fine while the ambient temp is low, but in summer you will have to pay close attention to it. The PC fans are a good choice for small stuff, but they get outclassed fast when you have to upsize. They say a human adult is about equivalent to a 100w heater so imagine 6 of them in your closet and that's how hot it will get with your light. When I'm working hard in my room, building things or moving heavy buckets, the temp rises sometimes 5f.
I'm not based in the US so home depot isn't an option, but I've got one of these I've been using for a while. http://www.amazon.co.uk/Digital-Temperature-Humidity-Meter-Thermometer/dp/B004GN9EH2/ref=sr_1_2?ie=UTF8&qid=1396626725&sr=8-2&keywords=thermometer Been using it on the floor between the plants, but it gets different measurements higher up in the tent. Also, I've just realised that putting it under the light means it gets affected by radiant heat as well and doesn't reflect the true ambient temperature... I've ordered a couple more of them so I can put one inside a cardboard box to keep it dark and put another one somewhere else, like half way up a side pole.. It'll also be good to compare them in similar places to see if there is much variation between each one. They're so cheap that I wouldn't be surprised if they weren't very accurate. Yeah, I've noticed that I warm up the tent when I open it up and lean half into it to work on things. Even with the front wide open. Once the HPS has replaced the LEDs, CFLs and tube heater though I'm sure it'll be cooler with the front open whether I'm working in there or not. Is that Canfan a Ruck? They're calling themselves Can now I think... Is it loud? My oscillating fans are both these: http://www.amazon.co.uk/Advanced-Nutrition-6In-Clip-Fan/dp/B00G3CE2EO/ref=sr_1_5?ie=UTF8&qid=1396627792&sr=8-5&keywords=growth+technology+fan and the USB fan I plan on taping halfway up a pole and focusing on the light is this: http://www.amazon.co.uk/Desktop-Power-Laptop-Table-BuyinCoins/dp/B005GYU8H0/ref=sr_1_1?ie=UTF8&qid=1396627812&sr=8-1&keywords=usb+desk+fan So not like a PC fan like people use to build their own small closet grows with, just USB powered - but I'll use a socket adapter for it. The additional draught right on the bulb should help a bit. To save a bit of money on electricity I'm probably not going to put them under the HPS till they've been on 12/12 for two or three weeks. Also, I think the additional blue light in the LEDs combined with the red CFLs being so close to the plants will help them keep shorter during the stretch. Even though I could be giving them another 200 watts of light... Bills bills bills... Thanks for your advice. If you like I will come back to this thread in a few weeks once I've actually set the HPS up and update you. If not, I wont bother. Ha!
That digital thermometer looks fine. You're right about the temp changing because of radiant heat hitting it directly but not much since it's white. It's good to know what temp the plant tops are so maybe hide it in the shade under the canopy and see how much the direct light is changing the temp. Probably only a couple degrees. It would also help to have a few around the tent/room if you wanna get obsessive about temps, and to get a range to check the accuracy of the thermometers, but after a while too many numbers gets annoying. I have my digital thermometer magnetized to the top of the vented hood and it's only about 2f warmer than if I hung it a few feet away. There's also a cheap-o analog one on the wall near the ballast which is always within a few f and %RH of the digital. I also have an IR laser thermometer that I measure the walls, floor ceiling and the plant tops. With enough airflow all the temps are within 5-10f, with the plant tops at 75-80f while the walls are about 73f or the floor in the shade near the air intake is usually around 65-70 depending on time of day. It's helpful to know where your hot spots are so you can move that stagnant air out of there, but even one oscillating fan and intake/exhaust is gonna keep most parts fresh in a tent. Now that might be overkill measuring everything, but I get to play with a friggin LASER! Speaking of PC fans and airflow, it's helpful to design the intake and exhaust to make temp control more efficient just like they do in PCs. Heat rises ect, so pull your cool dry air from down low and exhaust your hot moist air up high. But again, if you have fans mixing everything really well the whole room will be really close to the same temp / humidity. Like in my room I have the carbon filter down low so it doesn't steal too much warm air. It works that way in my head, but I haven't mounted it up high to see how much the temp drops. Here's the fan http://www.canfilters.com/fan_metal_rs6.html I don't know if someone bought the company. It's like quiet talking in the room, but can't hear it outside the room. Through a tent you would for sure hear it, probably sound like a white noise generator. I would look at the rated CFM of your fans to see how much air you're actually moving in and out. I think they say you should exchange your whole tent/room volume every five minutes. I don't remember exactly. Your USB powered fans are small and don't pull much power and the metal grates are pretty inefficient, so you can't expect them to move much air. It might work for you while its all small, but when the plants get bigger and you pop that 600w you'll probably be needing more cooling. When you switch to HPS start the light up a lot higher than normal so the plants can get used to it and slowly move it down over a couple days or so until you dial in the canopy temp you want. You'll have to check overnight temps to see how heat saturated your tent gets. When you choose to switch to 12/12 should be based on how big you want your plants to be. Some don't stretch much during flowering, but some will triple. Depends on a lot of factors so look up what other people's similar grows with your strains are doing. I hear color temp plays a roll, but with my Blue Dream (sativa dom hybrid) that is supposed to stretch a lot, it actually hasn't much, only about a foot max in a month of 12/12 600wHPS. It might still have 6-8 weeks left, so it might double in size, who knows. I'm dealing with soil problems too so that might be it. Saving power is a good thing, go to your power supplier's web site and look up how much it costs per KW/h, if it's tiered rates and on / off peak rates. It might only cost a few dollars extra a day starting out with the 600w sooner and will give you a nicer yield. 600w x 12 hours = 7.2 KW/h x 20 cents a KW/h is only $40 extra a month. Add up your other power, like heating / cooling you need for the bigger light etc and it might be worth it to spend a little extra early. It might also be a waste if the plants haven't filled out enough to take advantage of the light. You'll notice when they slow down in veg from your LED/CFLs that's when they'll need more light. You can find KW/h calculators online if you don't want to do the math. So yeah, that's a lot of info, maybe to an obsessive level. Up to you if you want to follow it all, since it's a pretty hardy plant it should live through a few misjudgments pretty well. Yeah, I'll watch for your updates.
Well here's an update for you: I went ahead and hung the HPS in there earlier than I originally planned. Haha! I go on those electricity cost calculator websites all the time man! They're great! Where I live at the moment I have a nice confusing split tariff which means I have to work out the cost of running everything at two separate prices throughout a 24hr period. On and off peak see. It actually means that I save a tonne because for 7 of my 12 hours my electricity is off peak and costs 3 times less. I decided that it made no real sense to hold off as I had already worked out how much it was all going to cost to run the HPS and 2 extra weeks of 600w (which is something like 380w more than my CFL & LED set up) just means that I need to grow about 2 grams more bud overall to cover the costs! Ha! Which I shall do easily with 2 extra weeks of HPS on them. Also, a few parts of each plant started showing signs of nutrient issues which I have attributed (optimistically) to the poor soil temperature and hopefully not anything more serious, so I thought the HPS would help there. (Also I haven't been giving them enough water recently because I couldn't get hold of big enough trays for the run-off, I think I might have caused some build up of nutes... or lockout or something... I think it's pretty hard to do too much damage with organic nutes though. Once I got good trays for the pots, in an effort to start cleaning the soil out a bit, I watered them with a lot of water (with a weak dilution of organic nutes) until and got a significant run-off. Now that I've got the trays I can go down to a slightly more spaced out watering schedule too. I had to water with a bit less and more often when I couldn't let them run off loads. Now that I can put more water through the pots I should be able to establish a better wet/dry cycle for them. Before I added the HPS, I was heating the tent with a tube heater (and the CFLs' heat), so it was hard to get a good spread of the warmth even with the oscillating fan. Now I've got the pots raised up above a Root!t heat mat that I use for seedlings in an attempt to keep the roots happier. It's on a timer (because I'm not coughing up for a Root!t thermostat for it) so it's on when the lights are off, and on 15 minutes/off 30 minutes, on 15/off 30, etc throughout the lights on period. I figured I should probably have it warming the roots a little with the lights on as well, rather than only when it was dark in case I actually make the roots warmer at night than at day (or too close in temperature) which would confuse the plants. This is still in trial mode now. I need to get a better spread of temp readings. Still awaiting my other 2 thermometers. I've got the one I own already in a little cardboard box on it's side now so that it's shaded from the lights, but so that I can still look into the box to read it. It's on the floor though, so I think the tops will be getting several degrees hotter. However, based on readings so far, that's not a concern. Temps haven't gone over 26C ish (sorry I mean 80F ish. I can't tell you how many times I've typed '80f in c' '20c in f' (or similar) into google whilst reading growing forums! I'm too used to UK celsius). Also the tops are a full 3 feet away from the bulb at the moment whilst they get used to it. I started it about another 3 inches higher for the first few days, but lowered it pretty soon as the girls were just loving it. I aim to get it to more like 20-18 inches from the tops eventually. 18 would be nice, but I'll have to see about those temps. Also my canopy isn't perfectly even. I topped one plant a few times and tied the other over as an experiment. So one is an even circle of lots of similar height tops, and the other is a bit more messy at the moment... Going to get some more string on it soon. This is my fan: http://www.ventilation-system.com/item/5096/Vents_125_VKOk_turbo/ It's 243m3/h which is 143CFM interestingly. The actual CFM will be much lower than that though as it's got to get air out through a 45 bend ducting elbow (solid plastic) that's attached immediately to the fan and then goes into the tent's wide 90 sock thing through the roof. So the bend will reduce it's effect (although having no ducting other than the elbow piece and the tent sock means I don't loose any CFM from a long duct run. I do also have it on a little speed controller though, so that it's running more quietly, but obviously that means more slowly too. Given the size of my tent (2'x5'x6' = 60 cubic feet) I think it's going to be fine. I haven't used it with a carbon filter yet though. Haven't needed to, but I expect I might soon. So this is going to affect CFM by like 20% again and hence temperatures again. I think I can turn the fan up more with the filter on though because having something over the end removes most of the sound. Now that the HPS is in there though I'm hoping to see some much better buds than my last cut. I like CFLs and LEDs a lot, but I don't really have the best set up to manage more than 2 plants through flower, and not even then with a what I would consider a good spread of light. Back when I used a 600w HPS and 400w MH my plants were much denser and I didn't even employ the amount of training and generally better standard of care for them that I do now. I think the CFLs and LEDs would still make excellent supplemental lighting though! (What do you think would be better? Two 100w LED panels or two 125w red CFLs?) I might get the two LEDs in the tent, either side of the HPS, once the plants are big enough to warrant it. I wont use the CFLs because of the heat and because I hang them as side lighting (no reflectors) and there probably wont be room for that. Considering that this previous crop was just a few bagseeds to play around with whilst I set up the tent I'm not too upset that one LSTed plant only yielded an ounce. (3 of 4 were male! Ha! Never growing bagseeds indoors again. But I've still saved hundreds to use for outdoor grows. Got strains from all over the shop!) However, only yielding an ounce was also a big incentive to get the HPS in there quicker. I have invested a little bit in the equipment this time and although it will all last for quite a few grows (minus the CFL bulbs and soil which I'll have to buy more of), I would still like to get enough medicine so that it works out cheaper than buying it elsewhere. The two I've got in there now look like they've got about 3 times as many branches and budsites as the bagseed plants did at this age. It's down to the good genetics obviously, but it's Pure Power Plant so it's also got that hybrid vigour AND I've got these ones in slightly more soil AND they had a waaay better start to life than the bagseeds I spontaneously germinated in shallow yogurt pots on a window sill! (It stunted their tap roots and stretched their stems something awful!) In my little veg box I've got 2 Big Bang Autos that I'm going to stick under the 12/12 HPS as well once they start budding. I know that the auto trait means they can have way more hours of light, but at the moment I have had them under a 100w LED for 3 weeks and then a 125w CFL in there as well for this week (now that it's removed from flower tent) and I think once they start budding (I don't want them under 12/12 before that... Inducing it even earlier in autos would be silly) putting them under the HPS would still be better than 24 hour light under the LED and CFL. You know... Because it's 600w... Also it would be tidier to keep them all in one place. What do you think? Ha! So yeah, there's my update.
Root temp should be cool, for anything larger than seedlings, so unless your grow room is actually too cold you don't need to warm them up more. I think it should be like 10-15f colder than canopy temp. So 65f-75f roots and ~80f canopy. Your root problems are probably more related to over watering than the roots being too cold or organic soil problems. The root zone is kinda self regulating, lets call it buffered, it's a large mass that keeps a pretty stable temp. http://www.envsci.rutgers.edu/~gimenez/SoilsandWater08/Lectures/ThermalPropertiesSoils.pdf The room warms up, the plants take up more water, and water evaporates from the soil, drying it out and cooling it down. My problem was the plastic nursery pots had crappy drainage and no side evap like smart pots, so the roots got swampy and caused trouble. Obviously because I over watered, but it was a combo effect with crappy pots. I drilled holes in the nursery pots and that introduced a massive influx of fungus gnats. I should have just got smart pots in the beginning, and not over watered. Rookie mistake. I don't know much about LEDs, so can't really answer what would be better. I would just use everything you can keep cool. More light is better. What's a "red" CFL? Like a party bulb or just a warm color temperature? I hear that putting autos on 12/12 is a waste, but not sure how that works if you're using twice as much light on 12/12 as 24/0. I would suggest that you move them into the 600w while it's on and move them back to the other light when the 600W goes out. Side lighting would be used if you're trying to grow the little suckers below the canopy. If you're just cutting all the undergrowth off then the 600w would be fine for a decent sized canopy. But more light is better! I noticed when my light is too close it doesn't reflect off the walls very well and light the backside of the plants. I would try and find the equilibrium between temp, distance, and how much light is reflecting onto the back side of the plants. I'm about 18" or so up from the canopy, and the plants are about 4 inches from the reflective materials and that seems to reflect a lot of light down to the dark sides of the plant. Mine isn't a perfect model, since my top heights are uneven, but it's a good place to start.
Yeah, I'm trying to make sure they don't get too hot by raising them. I've got each of the plants in a tray and then I've got one of the smaller trays I use for smaller pots upside-down underneath each of them to raise them an inch and a half off the floor and heat mat. When I first started using the heat mat I left it underneath the pots for too long into veg and baked the soil a bit... Well 'baked' is an exaggeration, but it got pretty dry and hard sometimes. I keep saying pots, but I've actually got all my plants in fabric 'pots'. Not the 'smart pots' brand though. They're overpriced. I've using a mixture of 'Root Pouch' ones and 'Plant !T Dirt Pots'. The root pouches are more like smart pots (I have one small smart pot a friend gave me) but cheaper and taller, and the dirt pots are square and much thicker fabric that doesn't look as recycled. They also have handy loops at the corners for bamboo stakes. Hmmm... Well maybe it's my watering that's the issue... I'm going to be making sure they get better run-off from now on. I didn't think I was over-watering. The plants themselves never show signs of overwatering, but maybe the soil itself is taking a toll. That's a good idea for the autos! I should be doing that already! Once they get big I might not be bothered with it though, because it will be quite a hassle moving them from veg box to flower tent every day as they're in separate rooms. But yeah, great idea. I can't believe I didn't think of it myself to be honest. It seems obvious now you've pointed it out for me! At the moment the two plants are only about 3 foot across in width, but they've only been flowering for 3 weeks ish so they'll be a bit bigger later and with the 2 autos in there too I'm thinking maybe LEDs as well.. We'll see when it comes to it. At the moment there's more than enough spread of light for them. I'll bring it down another foot over the next week or two (if the temps can hack it) and see how wide the coverage is then. At the moment it's lighting up a large space either side of my two plants though... so that seems a bit of a waste. I'm going to get rid of most of the undergrowth. I've been defoliating with these two. Especially with the LSTed one. In the next few days I'm going to give them a good trim and rearrange a few branches.
Oh also, by 'red' CFL I guess I mean warm yeah. So for flowering. You can get blue spectrum ones for veg too.
Sounds great! I only guessed at overwatering because you said you were watering until there was a lot of runoff and you think there is a nutrient problem. My understanding is that organic nutes don't really cause problems unless you're running out of nutrients or the living part of the soil gets throw out of wack. If you've overwatered you could be washing away nutes, or if the pots stayed wet or hot for too long it could have damaged roots and caused problems. If you watered really heavily before the roots have filled the pot then the water will just stagnate in the center where it won't evap. That was part of my combo of problems. You can get this all dialed in, I know it! Someone with more knowledge than me will be able to help you better. Maybe post a few pics?
Nah, I mean I only watered like that once I had trays for the run-off for them BECAUSE i hadn't been watering with much run-off up until the problem showed... But maybe I have still overwatered them... I've never used fabric pots like these before. Usually just go with cheap plastic ones. So I'm still getting used to watering in them. If you fill them up too quickly water just seeps through the fabric and out of the pots before going more than half way down through the soil or when you're watering close to the edges and the soil is dry it runs down the edges and out the sides. My method of watering them is to give each pot about a litre or half a litre sprinkled through a small watering can rose just so that all the soil gets evenly moist, then after an hour or so I go back in and give them the rest of their water (and nutes if i'm feeding them) so that the rest of the water can use the moisture that's already permeated the soil (hopefully quite evenly by now) as a sort of surface-tension based guide through the soil. I think this gets for better saturation. I also bubble my water with a aquarium pump and air stones as I assumed more aerated water wouldn't clog the soil much. I don't think their deficiency issue is too bad at the moment... I use biobizz nutes (just grow and bloom - none of the top max and heaven etc) in biobizz all-mix soil (each pot has about 15 or 16 litres of soil). I normally give them nutes most waterings. I'm thinking I should've upped the amount of flowering nutes by now though, so when the lights go on tonight I'm giving them the next step up the chart. Yeah, I probably will be uploading some pictures if the problem persists. For now though I'm waiting to see if my measures have worked
Based on max/min readings the temps are all good for now I think. However, the additional heat from the HPS is creating a fluctuation of around 20% in humidity between day and night (drier in the day). Not sure that that's ideal, but I don't think it's as troublesome as my other prioritised adjustments.
Been lowering the HPS slowly. Down to 28 inches now. Really want to get it to around 22. Will have to test the heat as I go though. It's peaking at around 85F with the thermometer at soil level. The weather is only going to get hotter as it gets closer to summer though. Put the carbon filter onto the fan which has made it quieter - allowing me to turn it up. But the filter obviously removes pulling power so I have to turn the fan up anyway... May take it off again if the smell is manageable. It isn't an issue a lot of the time.
Hi Joe I'm using a simlar size tent as you and wondered if I could pick you brains on controling temps etc? My temps maintain around the 30c, but as soon as I have the tent close rocket up. Since you've been using your HPS light, have you seen a major temp increase? Plus do you zip you tent right up ever?
The tent is zipped up all the time. Vent along the back is sort of open but the tent is backed right up against a wall so the airflow in could probably be a little better. It's quite drafty space though so I think that would help temps... Also I have to oscillating fans in the tent (one at each end) to blow over the plants to prevent any hot spots. It peaked at 32C today though and although the plants are fine, I'd really rather it didn't get any hotter... With the HPS on and the extractor fan running below full speed, pulling air out through a carbon filter the temps are around 30C most of the time. To make sure the HPS doesn't make the tent too hot it's on during night hours. This means it's off in the day with the warmer outside temperature so there's less of a difference between the light and dark cycle temperatures, which is nice for the plants. Do you extract air from your tent? It's the only way to keep the HPS heat under control.