Autos or Photos?

[Surfer Joe]

http://marijuanapassion.com/forum/showthread.php?t=54867

Its a bit long, but a pretty good discussion and information on light choices

Thanks. I just read the link and you seem to be saying that one 400 watt hps would produce more lumens and draw less power than my total of 700 watts of cfls. This is good news.

I have two considerations about my power usage.

One is that my garage in on a circuit that is 32 amps and already has several kitchen/laundry room appliances on it, so I have to be mindful of the total amps being drawn to avoid tripping the circuit. I have already told my wife that we must adopt the habit of not running the dryer and the washing machine at the same time because it could overload the circuit (dryers draw a huge amount of watts, which add up the amps).

The other is how to deal with the heat of a hps light. I can't really attach another exhaust fan to its reflector housing because I don't have the space, but I could let it vent passively through the reflector hood vent hole and up and out of the tent with some ducting. Heat rises, so would this cooling method be enough or would the heat in the tent get too high or maybe make the bulb break?

I need to study the options a bit more and see what would work for me. I realise that the growing qualities of the hps is better than the cfls, but I may have to accept the lower yield if I can't handle using a hps lighting setup.

 

[The Hemp Goddess]

By my calculations, I currently have about 40,000 lumens in there from the cfls and the grow tent has about 7 sq. ft., so I am getting roughly about 5000 lumens/sq ft.

A 400 watt hps is about 48000 lumens and a 600 watt is about 95000 lumens, so it seems that one 400 watt hps would provide a bit more light than all of my cfls, and a 600 watt hps would give me more than twice the lumens.

I don't know if the 600 would produce too much heat for my grow tent.
Could it be passively vented? That is, just connect the exhaust hole in the lamp reflector to some ducting and stick the other end out of a top tent vent so that the heat rises naturally through the vent duct and out of the tent.

Is it also correct to assume that the amps used by either lights are the same in term of total wattage? So 600 watts of cfl bulbs is the same drain as 600 watts of hid lights?

You can see how much more efficient HPS is lumen for lumen. And you will find that 400W of HPS will run cooler than the 700W of CFLs you have going now. The exhaust fan does not need to be inside the tent--I have mine in the crawl space.

A 30 amp circuit will hand quite a bit. I tend to believe that you should have no problems running a 400W, a fan or 2, and several kitchen appliances. However, if your breaker box is in your garage, you might want to run a dedicated circuit.

No, it cannot be passively vented. Your intake can be passive, but you are going to need a good quality centrifuge type exhaust fan to extract heat and bring in fresh air to your plants (a requirement for proper photosynthesis). You will not get rid of enough heat if you do it passively. In addition, like pcduck mentioned, you are going to want negative pressure in your space to contain odors.

I recommend T5s for vegging rather than MH.

 

[Surfer Joe]

Forty thousand lumens from CFLs is a whole bunch of CFLs. That would be somewhere around 650 actual watts...15 42W bulbs. Do you have that many? That many bulbs are going to be putting out a whole lot of heat. So, I am wondering if you figured your lumens correctly. What wattage (actual wattage, not equivalent wattage) CFLs are you using and how many?

No, it cannot be passively vented. Your intake can be passive, but you are going to need a good quality centrifuge type exhaust fan to extract heat and bring in fresh air to your plants (a requirement for proper photosynthesis). You will not get rid of enough heat if you do it passively. In addition, like pcduck mentioned, you are going to want negative pressure in your space to contain odors.

I recommend T5s for vegging rather than MH.

I think it's right.
I have a 250 watt red (2700K), a 125 watt blue (6500K), 5 x 35 watt reds (2700K) and 5 x 30 watt blues (6500K). The 250 is rated at about 12,500 lumens, the 125 at about 5,500 lumens, the 35s at about 2300 lumens and the 30s at about 2000 lumens.
This totals 700 watts and 39,500 lumens.

The tent has a carbon filter with an extractor fan drawing the tent air out the top. The air comes in through a bottom vent hole passively. The 250 cfl is in a reflector but not vented in any way, and the 125 cfl and all of the other smaller cfls just hang around the plants.

The tent never gets above 30C with all those lights on, and when the weather gets a bit cold the inside temp is about 25C. I worry about it getting too cold at night when the lights are out so I put in a little 55 watt tube heater next to the pots to keep them a tiny bit warmer.
If it gets really cold, I have a small 700 watt oil radiator that I can place in the tent to run when the lights are out.

The lights are all less than a foot away from the plants on the top and sides and there is a small oscillating fan that sweeps back and forth over the plant tops and the space above where the 250 cfl hangs.

I would still use the carbon filter and extractor fan in the tent for air exchange as well as odor control, but was hoping that I could put in a 400 watt hps in a vented reflector hood and just connect the reflector vent hole to the top vent hole in the tent with some ducting and let the heat rise through the reflector vent hole by natural heat rising convection.

I realise that I have spent more on the cfl bulbs than I would for a hps bulb and reflector setup, but I was worried about the heat buildup of a hps light in a small tent. But if I can manage the heat issue with my current air circulation setup, I would like to try hps lighting.
Do you still think that the heat issue would be a stumbling block without actually connecting an extract fan to the hps reflector hood?
I could easily place the hps ballast outside the tent if it was also a heat producer.
Could my extractor fan be rigged to run both the carbon filter and the heat ext ration from the hps light?
I have attached a sample plan to show my current setup and to visualize my new idea. How would the setup, sucking the hot air from the hps light out through the carbon filter, affect the filter or the potential odors.
Would hot air going through the carbon filter create any problems?

 

[ross]

If you have an air cooled hood I think the best set up is carbon filter>>>>ducting>>>>hood>>>>ducting>>>>fan>>>>ducting>>>>out

 

[Surfer Joe]

If you have an air cooled hood I think the best set up is carbon filter>>>>ducting>>>>hood>>>>ducting>>>>fan>>>>ducting>>>>out

Thank you. I see what you mean. The problem will be whether I can actually rig that up in my tent.

 

[Locked]

Any chance you coould vent the tent out your roof? This would do away with the need for a carbon filter and would be less stress on your fan. I vent out a 2nd floor window. Like I said before, the negative pressure created in the tent keeps odors at bay in my room.

 

[Surfer Joe]

Any chance you coould vent the tent out your roof? This would do away with the need for a carbon filter and would be less stress on your fan. I vent out a 2nd floor window. Like I said before, the negative pressure created in the tent keeps odors at bay in my room.

Unfortunately, no. The tent is in a small garage and vented air can't be channeled up through the roof or out a window.

 

[Locked]

Unfortunately, no. The tent is in a small garage and vented air can't be channeled up through the roof or out a window.

Gotcha.

 

[Hushpuppy]

If your tent is too small for you to connect it with the filter inside, then you can place it outside and run the air through it backwards. It won't be as efficient but it will work, and for a 400w hps, it should do fine unless the filter is very small. But you will have to use an extractor fan as convection will not be nearly enough even without having a filter on it

 

[The Hemp Goddess]

Actually, lumen for lumen the CFLs generate more heat than an HPS. This is one of the reasons that it is important to research before you buy anything. CFLs cost more to purchase initially, they put out substantially more heat and they produce a lot less bud. I understand that you are going to have to use them now that you have purchased them, but be sure to run all your growing purchases by someone who is knowledgeable about this. Virtually all of us have a storeroom of ill-conceived purchases.

A passive exhaust out the top will not work. You do not need to have your fan in the tent. I have ducting connected to by reflector and then to the fan which is located in my crawl space. You are better off pulling the air through the fan. The filter (if you need one, I don't use one) can be located on the other side of the fan.

You are going to have to have some kind of air exchange in the garage. You cannot just keep recycling the same old air. Your plants need a continual supply of fresh air all the time the lights are on. You are going to need some kind of fresh air intake and somewhere to exhaust the stale, hot, moist, CO2 depleted air. You do need some kind of oscillating fan in your space.

Sometimes we have to alter things if we want to grow. IMO, you are going to have to have some kind of opening from the the garage to the outside air. Can you take ducting up through the top of your tent and into the attic area? If you are in a garage, you must be near a gable end that you could exhaust out of. About the dark period....are you flowering already?

 

[Surfer Joe]

Virtually all of us have a storeroom of ill-conceived purchases.

Lol...I already have!

You are going to have to have some kind of air exchange in the garage. You cannot just keep recycling the same old air.

You don't know my garage. It is like a sieve. It's falling apart. You can see through the single brick walls and there are gaps of 1/2 inch or more throughout the brickwork. I'm surprised that it's still standing. It's full of fresh air.
I didn't mean to imply that it was a sealed space, and it does have a window, which doesn't even close, but it's not in a location that I can just vent outside without other people smelling something so I do need a filter.

I understand the consensus that the hps light will need some active cooling, and I think that I can rig the single extractor fan to suck air through the filter then go through the light and then out of the tent.

I think that if I am cooling the light, then I can go to a 600watt to really pump out the lumens in my little tent.
I think that 95000 lumens in a 7 sq ft space should be quite helpful- or can you overdo it?
Would a 400watt hps be a better choice for a 7 sq ft space? That's only about 48000 lumens.
I saw a few ballasts that are dimmable, so I could set it lower for the veg state and then to max for the flower stage.
Thanks for your advice.

 

[The Hemp Goddess]

I found that when I get over about 7500 lumens per sq ft, I do not see much if any increase in growth or bud size. Without CO2 enhancement, there is a finite amount of light the plants can utilize. I had a 600W in a tent the same size as yours, but ran it at 400W for flowering. I used T5 fluoros for vegging.

And about ventilation, you need to exchange the air regardless of heat or the type of lighting you use. I like to exchange the air in my space a couple times a minute, but doing it once every 2 minutes or so will be sufficient. I would run ducting to the attic area, put the fan there, and run ducting out the gable end near the peak of the roof. You may not even need a filter.

 

[Surfer Joe]

I found that when I get over about 7500 lumens per sq ft, I do not see much if any increase in growth or bud size. Without CO2 enhancement, there is a finite amount of light the plants can utilize. I had a 600W in a tent the same size as yours, but ran it at 400W for flowering. I used T5 fluoros for vegging.

And about ventilation, you need to exchange the air regardless of heat or the type of lighting you use. I like to exchange the air in my space a couple times a minute, but doing it once every 2 minutes or so will be sufficient. I would run ducting to the attic area, put the fan there, and run ducting out the gable end near the peak of the roof. You may not even need a filter.

Thanks.
So do you think that for a 7sq ft space a 400 watt hps that provides about 48000 lumens would be a good choice?
Or should I go for a 600 watt with a dimmable ballast or simply set it further away from the plant tops since light intensity falls off quickly as the distance increases?
Just what sort of distance is recommended for the hps lights from the plant tops?

I know that the cfls need to be kept as close as possible while also avoiding burning the plants, and that some should be placed around the plants to illuminate the sides as well, but the photos of hps light setups all seem to show just the one light hanging above the plant tops at a greater distance.
Is the lumen output of a hps light calculated based on a particular distance from the plants?
Does the light tend to reach down into the plant better than cfls? Or do you try to create a topped or fimmed plant to make better use of the single light from above?

 

[sunakard2000]

distance the HPS is usualy kept if in an air cooled hood is about 18 inches to 2 feet away from the canopy, close enough to prevent too much stretching yet far enough to keep the tops from burning, as for all the other questions i think i can sum it all up simply, HPS is better all around hands down, uses less energy per lum, much higher intensity light. either way you slice it your better off with High Output T5 fixtures for vegging plants and a HPS for flowering, both have high outputs with a smaller draw on electricity then CFLs, both T5s and HPS while they do put off heat will run much much cooler then CFLs.
CFLs put out a ton of heat, have low intensity light, meaning weaker energy photons so they must be kept close and in large numbers, draw more power per lum and in the long run will cost more with electric usage. remember your end product is going to reflect in your setup, and a good setup for growing quality bud is gonna cost a bit of money but in the long run youll be comming out ontop, not only paying less on electric bills, temps will be far easier to control and youll be producing much higher quality bud then with CFLs, granted iv seen good quality product come from CFL grows but its usualy whispy airy buds because the light strength is just too low, the plants dont get the quality light they need. if your serious about growing quality product, nice fat dense nugs, then your going to have to invest in this hobby a bit more, i know its hard to swallow dropping large chunks of a few items but quailty in is quality out.

 

[The Hemp Goddess]

The distance HPS lamps should be kept from the canopy is as close as you can get them without burning or bleaching the plant. I keep my HPS a foot or so away, depending on how crowded the space is. A 400W should work just fine for that tent. I doubt that the plants will be able to utilize more lumens than that. However, if you think that you want to go with a larger tent later down the line, you may want to get the 600W.

The lumen output is measured like all other light bulbs. The are measured as output at the bulb. Yes, the light reaches down into the plant better than CFLs.

 

[Surfer Joe]

Thanks a lot for all the advice.
Is there any difference between the lamp reflectors for 400 or 600 watt lamps?

The bulbs are not so expensive and if the reflectors are the same connections, it should be possible to buy different wattage bulbs.
Or do different watt bulbs require different watt ballasts or plugs?

Can a 600 lamp reflector also run a 400 watt bulb or vice versa?
If I'm locked into a single choice, it seems the best choice would be a 600 watt reflector with a dimmable ballast. It would be the most flexible and future proof.

Also, you all keep talking about hps lights but I thought that you should use a mh light for the veg growth and a hps light for the flowering stage.
Is it ok to use a hps light for the whole grow?
Do lamp holders accept either type bulb or is that another holder/reflector that you would need to get?

 

[The Hemp Goddess]

No, the wattage of the ballast must match the wattage of the ballast. This is why dimmable ballasts are so popular. You have the versatility of being able to use different wattages. Electronic ballasts will run both MH and HPS.

I used to run MH for veg, but now use T5 fluorescents. They put out about the same lumens per watt as a MH, but spread the light better and run cooler. You can use a HPS all through the grow, but vI prefer a blue spectrum for vegging if I have a choice.

 

[Surfer Joe]

No, the wattage of the ballast must match the wattage of the ballast. This is why dimmable ballasts are so popular. You have the versatility of being able to use different wattages. Electronic ballasts will run both MH and HPS.

Thanks. I was looking at dimmable ballasts and noticed their power usage and was confused.
The ballast is rated at 600 watts and uses 2.7 amps. Does that include the lamp it is running, or does a 600 watt bulb use any additional amps in addition to the ballast?
This could influence my choice because I am mindful of the limits of my garage circuit load.

 

[sunakard2000]

ballast draws power to run the bulb, the bulb its self doesnt pull from your circuit it gets its power from the ballast. but the ballast can only run the wattage bulb its designed for, so a 600 watt dimmable uses a 600watt bulb, if the ballast pulls 2.7 then its pulling 2.7. your additional draw on your circuit would be from exhaust fans, circulation fans and anything else running like air/water pumps, timers, all the other necessities.
like THG said if your planning on or even think you might upgrade the size of your grow space defently go for the 600watt, dimmable if you like since your in a smaller tent you could drop it down a knotch and it should be perfect.

 

[Surfer Joe]

Thanks. I thought that might be the case, but you never know.
I have everything running ok with all the electrics now and I have 700 watts of cfls, so one 600 watt hid system should actually draw less amps than all of the cfls since amps are just watts divided by volts.
This pretty much seals the deal.

Do you consider the lumatek or the sun master brands of ballast good, or would you recommend other brands? I see them a lot in the online stores.

Thanks for all of the advice. This thread sure drifted away from autos or photos!