Before we can really offer you any advice we need to know what you plan to use the lights for. "indoor growing" is just far to broad of a subject.

With more information we can better offer advice.

SCG

Herb, leafy greens, peppers and small tomatoes.

Apparently the only difference is lumens per watt, which means about 10% more lumens per watt from T5

Yes, that is pretty much true. T5's are about 12% more efficient.

Your question is going to be how much light you want to provide. You can grow them under 2 T8 bulbs or 1 T5 or you could go better and use 2 T5's or even better go to 3 T5's and better yet 4 T5's...you get the point.

While I find 2 T8 bulbs over 2 trays adequate for seed starting I prefer to grow under T5's. I have several 8 bulb fixtures that will fit 4 trays underneath each. You can't get T8's close enough together to provide that much light.

IME, my plants did better with more light, especially when I wanted them to bear fruit or flower.

You will have to see what works for you. IMHO the more light the better.

SCG

If you buy a florescent fixture for t5 or t8, are they interchangeable for the bulbs? So you can upgrade the bulb you're using?

T5 and T8 are not interchangeable, unfortunately.

T5s and T8s are suitable for growing leafy greens, herbs, and other non fruiting or blooming plants. The highest efficiency gain in T5s vs T8s is that the bulbs are more compact allowing more of them to be used in the same space. Thats still not worth it in my opinion. Light from these sources dont penetrate the canopy at all, and thats critical. I know lots of lettuce is grown under fluroescents, but it doesnt grow 1/10th as fast as under metal halide for example.

Im currently building a vertical indoor leafy greens growing system made up of over the door show organizer, with a 1000w metal halide hung vertically in the center with no reflector. This system is designed to churn out over 300 salad heads per month (from seedlings). Yes im selling the produce, so my figures are very serious, realistic, and backed by 5 years of research.

The challenge with metal halide and high pressure sodium comes in the form of light distribution, as point source lighting isnt even at various distances from the bulb.

Youre gonna find me annoying, but I must tell you that NOTHING comes close to metal halide and high pressure sodium. Seeing is believing.

Bite the bullet and get a kit, youll thank me for it later.

Khaled

I will have to disagree. I gave up HID systems for T5HO's. While every year I grow different things they always include leafy greens and flowering and fruiting plants. My growth rate is the same with HID as it is T5's.

The advantage, for me, of HID systems was they cast a slightly larger footprint than my fluorescent set up.

The problem with HID systems is the heat they produce. I don't like, or like the expense and electricty, to totally rely on fans or exhaust systems to dissipate the heat. Therefore the lights must be farther from the plants than with T5HO's. Since light attenuation is exponential (quadratic) the extra distance the HID systems had to be away from the plant to avoid scorching negated the extra intensity they produced. Thus the light penetration is exactly the same for both T5HO's and HID systems. The only way the HID systems 'penetrate' better is if they are closer making use of cooling bulbs, fans and/or exhaust systems critical. If you can not get rid of the heat HID is NOT for you.

The other benefit, again for me, is that my grow room only has 7' ceilings so with HID I could only vertically grow one rack while with T5's I can stack 2-3 high increasing my growing footprint without increasing the physical footprint.

While HID systems are great they are not for everybody.

I would be very interested to see your setup. 300 plants a month is a lofty goal under one light and I would love to see you succeed.

SCG

Heat and ventilation are easily dealt with if you have large enough volume of air to work with. Putting a 1000w hid systems in a 5X5 room is calling for problems.

They are, for growing purposes, vastly superior. Thats why you never seen greenhouse growers using T5 lights. A 1000w HPS puts out up to 155 000 lumens. This floods a 4X4 square with as much light as the summer sun. Fluorescents, no matter what kind, don't even come close, and they do not penetrate canopy, so forget any plant taller than a few inches. Yes, your plants will grow under T5s, but theyll never reach their full potential like they do under HIDs.

Youre right that they arent for everyone. Its gets expensive very quickly when you get setup with professional grow equipment. It also gets more complicated as accelerated photosynthesis/metabolism brings about its own set of problems.

Im just a sucker for HIDs lol

Khaled

The ability for fluorescents not able to penetrate is a bad internet information regurgitation and really has no basis on fact.

To not scorch my plants I had to keep the 1000w HPS 36" away from plants and the 600w 24". Here is how the numbers crunch based on lumens which is measured 1' from the light source. These measurements where with the plants I grew, some more tender to heat than others, and my room characteristics. YMMV

1000w 160,000 lumens, 40,000 at 2' and 17,000 at 3', 10,000 at 4'
600w 100,000 lumens, 25,000 at 2' and 6,250 at 3'
8 Bulb T5HO 40,000 lumens

Now if your plants are 1' tall and the 1000w is 3' off the canopy, the 600w 2' and the T5 2" at the base of the plant you would have the following lumens.

1000w 10,000 lumens using 1000W+ power
600w 6,250 lumens using 600w+ power
T5's 40,000 lumens over area (~15,000 spot) using 432w power.

The ability to keep the T5's closer gives them the advantage of providing as much, if not more, light.

Where the HID shine is when you have cooling systems or extra fans that allow you to keep the lights closer. They now "penetrate" or provide more light deeper due to a more intense source. This comes at the cost of equipment, sometimes specialized, and electricity. The compensation with fluorescents on tall plants is to simply add side or mid fixtures. The other bonus to HID was the footprint was larger than my T5's, the 1000w being the furthest away had the largest.

While T5's are not conducive to the greenhouse application many "pro" growers of the largest cash crop in North America are now using fluorescent fixtures with no drop in yield. The technology has been out long enough they have figured it out.

Good luck with your grow and I hope to see pictures of your setup and yield.

SCG

Use a photometer and youll see just how true this regurgitation is. A T8 bulb puts out 3000 lumens and distance drops according to the inverse square law just as quickly as other lamps. 3000 lumens spread over 4 foot of length isn't much light. It takes 50 of them to equal one 1000w hps. Plus youll have much more heat as fluorescents are less efficient at converting electricity into PAR lighting, so they put out more heat per watt. Fluorescents grow puny, leggy, stretchy plants. As for scorching your plants, a gradual exposure to more light everyday will allow you to keep your tops as close as 3 inches from the bulb. I do it all the time. You cant argue with real life.

You telling me that the growers of the biggest cash crop have switched to T5 with no drop in yield tells me you're either following closet growers or havent very much tested around with grow lighting. T5 do have their benefits, but youll pay for it heavily in yield. Plus its an ultra biaised statement as a very very small percentage of the use T5 lighting.

As for price, I get my lights from a place that resells equipment seized by the police from cannabis growers and pay 95$ for a complete 1000w system, either hps or mh ( just got 2 lumatek 1000w digital ballasts for 160$ a few weeks back.

Pro growers use the light that replicate both the suns spectrum and intensity as closely as possible. Those lights are mh and hps.

Khaled

Yeah, all of which is moot (and silly to boot) when you don't have the electrical infrastructure required to run all of that. EG, most residences are wired to have a single 15A circuit per bedroom. Not to mention startup costs.

If you've got the money to retrofit a room or an entire workshop area with fans, ventilation, and multiple circuits, I contend that you also aren't worried about the expense of the equipment nor the expense to run it. The payback given the initial expense won't be seen for decades, if ever.

As for fluorescents generating the same amount of heat as a HID or sodium lamp or what have you - it is to laugh! I can lay hands on any or all of my T8 bulbs and not get burned or even suffer discomfort. Temp at the (non-overdriven) bulb is about 100F tops. There's no way I'd try to touch a HID or similar bulb with a bare hand unless it had been off long enough to cool to room temp.

Sure, the more fluorescents you have, the more heat will be generated under the lamps - which is why you still need (nowhere near the same amount of) fans. 'Sjust physics. So?

I'm growing tropical citrus with T8 fluorescents alone in my bedroom. I'll be adding some edible gingers as well, after I overdrive my fixtures. I'm looking to replace - or rather augment - my old Lights of America fixtures with some newer fixtures that will allow me to stack more of them in the same space - hence increasing the light.

Currently I get sufficient cooling from a single oscillating fan - that will likely change once I have a full shelf-load of overdriven T8s in banks of 8 to 10 per shelf. As it is I have to run a heavy duty extension cord (intended for construction use for things like table saws etc) under the doors and into the laundry room to get access to a different 15A circuit.

Given I'm currently in a desert climate I don't even have the issues of humidity that some folks might have to deal with, but you still need proper ventilation, cooling, and you have to consider and conform to the available power given the load you need to put on the circuit.

It is not only possible, but eminently practical, to have a grow area in a conventional residential home with fluorescents alone, WITHOUT having to rewire or knock holes in the walls, ceilings, floors, and roof to get enough ventilation and cooling that you don't burn down the house by overloading circuits or failing to properly cool/ventilate, or (in non-desert climes) ending up with black mold on your walls from the improperly vented humidity because you couldn't afford to knock holes etc (or because you are renting).

Even if I thought it was warranted to go to HID or any of the other high-heat generating options, I literally do not have the space such a set-up requires.

My fluorescents do not grow puny leggy plants. If yours do, you're doin' it wrong.

As for the OP: I use T8s because they are much easier to find locally - both fixtures and bulbs - and still way cheaper than T5s. I do not find that the T5s justify the extra expense or trouble to find the fixtures and replacement bulbs. I can still get plenty of T8s into the area where I need them and if I overdrive them, I can eke even more light-per-square foot out of them in the same space.

The trick is to use narrower profile fixtures. I have the old Lights of America fixtures (they ran about $6 to $8 when I bought them) but I can only hang 2 per shelf currently because they are so wide (about 7" to 7.5" each).

Both Home Despot and Low's carry narrow profile 2-bulb fixtures in the T8 flavor - be careful because a lot of the cheaper fixtures are T12. The range in price is about $15 to $30. Last time I checked ballasts between lesser and more expensive models (not these particular lights though) the ballasts were either exactly or practically the same.

I don't know if you have Low's (Lowe's) or Home Despot (Home Depot) in Canada, but you must have similar big box hardware stores. Menards is another US source of cheap fluorescent strip lights.

I don't worry too much about the ballasts because as they die, I expect to replace them with better ballasts anyway - plus I intend to overdrive. My LOA fixtures have pretty cheap ballasts in them - one of them never worked properly out of the box in fact - but 3 of the 4 I bought are still functioning after about 7 years. I should have exchanged the non-functional one but never got around to it - so I'll just buy a new ballast for it when I get ready to go into overdriving mode.

I don't know what you are planning to grow - but 8 T8 bulbs will grow an awful lot of stuff. My citrus seedlings are currently under 4 T8 bulbs and they are doing extremely well. They will need more light as they grow but for now - up to about 5" tall - they are getting plenty.

If you then turn around and overdrive your T8s, you'll be getting another 50% boost to the light output, per bulb. Your ballasts will actually run cooler, though your lamps will run slightly warmer.

Not all ballasts can be overdriven, but most modern T8 ballasts can be. No magnetic ballasts can be overdriven. If you're interested, I've got a ton of links about overdriving fluorescents that I'd be happy to share.

Even without overdriving, double the T8s will out-light half the number of T5s. Just look for narrow profile lights, if possible, so you can squeeze more of them over each shelf.

MisterK - Only picking your brain as you are the self proclaimed expert.

I do have photometers and quantum meters. T5HO's can produce nearly, and often more depending on the bulb, PAR values.

While not to call you out I suggest everybody take their hand and hold it 3" away from the incandescent bulb in their house, probably a 60 or 100w. I bet in a few minutes it would be warm. Typically that is how we judge temperature for grow lights... if you can't hold your hand there for 3 minutes it is too hot. Now Imagine over 10X that heat for a 1000W....nope...no way plants can be this close.

HID while it works, is old technology.

If I wasn't so lazy I would overdrive T8's, yet with the slim fixtures I can get for T5's the benefit of over driving T8's is slim. Probably at a slightly higher cost but oh well...

BTW I would love to see a video of your plants 3" away from a 1000w HID....even better your hand. You hold it there for 3 minutes and I will bow to you.

Internet information regurgitation sucks.

And btw zensojourner my experiences, although somewhat different, mirror yours.....I have produced citrus under T5-T8 setups as well. I have had larger yields under lights than I have outside (cherry tomatoes).

have a great night.

Oh, Khaled if you want some more HID's I will trade you for T5HO's, so cheap

SCG

Enjoyed reading the replies pertaining to gardev's [T5 vs T8 and equivalent] post, and truly respect the different opinions/experiences of the various light sources that were mentioned.

In regards to ("Pro growers use the light that replicate both the sun's spectrum and intensity as closely as possible. Those lights are mh and hps.")... might be really hard to convince the pros that have switched from MH/HPS over to LED.

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Yeah, definitely do not have the money or space for that, LOL!

Wow!! that is some serious lighting....I can't wait till it comes down in price enough that I can afford it.

zensojourner you have convinced me to get off my lazy butt and overdrive the armful of T8 ballasts I have. I would be interested in your links.. TIA.

SCG

OK, I'm just going to throw these out there. Forgive me. I haven't sorted them yet and I have a terrible awful hateful cold. At my age a cold is just not the same experience it used to be, LOL!

So here are ALL my links, in no particular order, and probably some repeats, in a giant noodly mess.

http://www.tomorrowsgarden.net/node/22
http://reocities.com/heartland/pines/7557/overdrv1.html
http://www.buylighting.com/T8-Fluorescent-Ballasts-s/616.htm
http://www.fatalii.net/Articles/Customized_fluorescent_lamp_system
http://www.acuitybrandslighting.com/library/ll/documents/specsheets/td-100.pdf
http://www.standardpro.com/ballasts-info/fluorescent-ballasts/faq#crest-factor
http://www.irf.com/technical-info/designtp/temp004.pdf
http://www.lightingassociates.org/i/u/2127806/f/tech_sheets/Basics_of_Ballasts.pdf
http://www.lrc.rpi.edu/programs/nlpip/lightinganswers/t8/03-t8-power.asp
http://forum.grasscity.com/absolute-beginners/564033-lighting-guide.html
http://forums.gardenweb.com/forums/load/lights/msg1023085115379.html?21
http://web.archive.org/web/20040629124310/http://forums.gardenweb.com/forums/load/lights/msg111229472000.html
http://www.geocities.ws/overdrive_lights/
http://forums.gardenweb.com/forums/load/lights/msg0200530730707.html
http://forums.gardenweb.com/forums/load/lights/msg0213125528645.html
http://web.archive.org/web/20060102052948/http://www.plantedtank.net/odno.html
http://www.plantedtank.net/forums/showthread.php?t=21257
http://www.lrc.rpi.edu/programs/nlpip/lightinganswers/t8/03-t8-power.asp
http://web.archive.org/web/20080103183037/http://www.geocities.com/teeley2/overdrv1.html
http://web.archive.org/web/20080223040411/http://www.plantedtank.net/forums/lighting/21257-odno-measurements-power-consumption-vs-light.html
http://www.plantedtank.net/articles/DIY-Light-Hood-Fan/10/
http://web.archive.org/web/20080220090814/http://www.lightsearch.com/resources/lightguides/ballasts.html
http://web.archive.org/web/20080223040411/http://www.plantedtank.net/forums/lighting/21052-comparison-lighting-types-lumens-watts.html
http://assets.sylvania.com/assets/documents/faq0042-0700.4cdec34c-d464-4f9e-a6cf-0b6ec9a934c0.pdf
http://www.donsbulbs.com/cgi-bin/r/d.pl/initial_lumens.html
http://reocities.com/Heartland/Pines/7557/overdrv1.html
https://www.icmag.com/ic/showthread.php?t=17260
http://www.oocities.org/teeley2/overdrv1.html

http://www.acuitybrandslighting.com/library/ll/documents/specsheets/td-100.pdf
http://www.standardpro.com/ballasts-info/fluorescent-ballasts/faq#crest-factor
http://www.irf.com/technical-info/designtp/temp004.pdf
http://www.lightingassociates.org/i/u/2127806/f/tech_sheets/Basics_of_Ballasts.pdf
http://www.lrc.rpi.edu/programs/nlpip/lightinganswers/t8/03-t8-power.asp

Parts and supplies:

https://p11.secure.hostingprod.com/@nextechlighting.com/ssl/product_info.php?cPath=1&products_id=93&osCsid=759ef60819b0f4e334968e847d419dc0
http://www.lowes.com/pd_420867-43921-MXL-103_4294565967__?productId=4013485&Ns=p_product_price:0&pl=1¤tURL=%3FNs%3Dp_product_price%7C0%26page%3D1&facetInfo=
http://www.lowes.com/ProductDisplay?partNumber=163719-337-SNF232RC&langId=-1&storeId=10151&productId=3335372&catalogId=10051&cmRelshp=req&rel=nofollow&cId=PDIO1
http://www.amazon.com/Sunpark-SL15T-electronic-multiple-fluorescent/dp/B005HQL0KQ
http://www.amazon.com/gp/product/B00ER7NYDM/ref=pd_lpo_sbs_dp_ss_2?pf_rd_p=1944579862&pf_rd_s=lpo-top-stripe-1&pf_rd_t=201&pf_rd_i=B005HQL0KQ&pf_rd_m=ATVPDKIKX0DER&pf_rd_r=1512MJV7X1SG1RSWWFBD
http://www.amazon.com/gp/product/B005HR0FPG/ref=pd_lpo_sbs_dp_ss_1?pf_rd_p=1944579862&pf_rd_s=lpo-top-stripe-1&pf_rd_t=201&pf_rd_i=B005HQL0KQ&pf_rd_m=ATVPDKIKX0DER&pf_rd_r=1512MJV7X1SG1RSWWFBD
http://www.panbo.com/archives/2013/12/3m_scotchloks_is_my_love_so_wrong.html
http://www.goodmart.com/products/halco-lighting-e232is-120-r-sl-50118.htm
http://www.homedepot.com/p/Lithonia-Lighting-2-Light-White-T8-Fluorescent-Residential-Shop-Light-1233-RE/202994372
http://www.lowes.com/pd_245546-58659-NXU-6001-B_4294857041__?productId=3168049&Ns=p_product_price:0&pl=1¤tURL=%3FNs%3Dp_product_price%7C0%26page%3D2&facetInfo=
http://www.lowes.com/pd_420867-43921-MXL-103_4294857041__?productId=4013485&Ns=p_product_price:0&pl=1¤tURL=%3FNs%3Dp_product_price%7C0%26page%3D2&facetInfo=
http://www.homedepot.com/p/Commercial-Electric-Rugged-2-Lamp-Hanging-Fluorescent-Gray-ShopLight-CESL402-27/203725928
http://www.homedepot.com/p/Lithonia-Lighting-All-Season-Shop-Light-4-ft-2-Light-Grey-T8-Strip-Fluorescent-1242ZG-RE/202052422
http://www.lowes.com/pd_163719-337-SNF232RC_1z0vgb3+1z0vjm2__?productId=3335372&Ns=p_product_price:0&pl=1¤tURL=%3FNs%3Dp_product_price%7C0%26page%3D1&facetInfo=In Store
http://www.homedepot.com/p/Lithonia-Lighting-2-Light-White-Electronic-Channel-Fluorescent-Strip-Light-C-2-32-120-GESB/100543144
http://www.homedepot.com/p/Commercial-Electric-Super-Bright-3-Lamp-Hanging-Fluorescent-Silver-Black-ShopLight-CESL404-05/203725921
http://www.homedepot.com/p/Lithonia-Lighting-2-Light-High-Output-Multi-Volt-T5-Compact-White-Fluorescent-Strip-Light-ZR-2-54T5HO-MVOLT-GEB10PS/203137160
http://www.homedepot.com/p/Lithonia-Lighting-4-Light-Grey-Heavy-Duty-Fluorescent-Shoplight-1284GRD-RE/202968125
http://www.homedepot.com/p/Philips-4-ft-T8-32-Watt-Daylight-Deluxe-6500K-ALTO-Linear-Fluorescent-Light-Bulb-10-Pack-422949/203466585?N=5yc1vZbm3zZ1z0twpmZ1z0vvri
http://www.homedepot.com/p/ViaVolt-54-Watt-4-ft-T5-Fluorescent-Replacement-Lamp-10-Pack-VT54B-10/203891792#customer_reviews
http://www.homedepot.com/p/ViaVolt-4-ft-T5-865-High-Output-6500K-Fluorescent-Grow-Light-Replacement-Bulb-VT54B/203124383
http://www.homedepot.com/p/Philips-4-ft-T8-32-Watt-Daylight-Deluxe-6500K-ALTO-II-Linear-Fluorescent-Light-Bulb-2-Pack-422963/203466587?N=5yc1vZbm3zZ2bcoyeZ1z0twpmZ1z0vvri
http://www.homedepot.com/p/Halex-3-8-in-Twin-Screw-Non-Metallic-Cable-Clamp-Connectors-5-Pack-20511/100133208
http://www.amazon.com/dp/B0051QKTRC/ref=wl_it_dp_o_pC_nS_ttl?_encoding=UTF8&colid=15S72TD6TYB1N&coliid=I2UG7LD6N0IEB8
http://www.amazon.com/dp/B002CYVGX2/ref=wl_it_dp_o_pC_nS_ttl?_encoding=UTF8&colid=15S72TD6TYB1N&coliid=I1BMFTJI3E3ISE
http://www.amazon.com/dp/B005CJBIPA/ref=wl_it_dp_o_pC_nS_ttl?_encoding=UTF8&colid=15S72TD6TYB1N&coliid=I214UIEMT2RDC0&psc=1

Here is a link that might be useful: Pulley system to raise and lower fluorescent strip lights

This post was edited by zensojourner on Thu, Nov 20, 14 at 2:02

One thing zensojourner mentions is growing citrus in the bedroom. I had to laugh because I am growing my various indoor plants all in my living space as well, so the quality of light, intensity, color, any sound and overall feeling/ vibe (warm/ cool) is important because of living around it. In my case, I want the plants and the set up I have to be at least "interesting" if not attractive to look at. it gets challenging, running cords, hanging lights... to not start having your home look like a garage/ shop. Right now, my indoor florescent lights are doing great for my three happy, madly flowering Meyer lemons (although fungus gnats and aphids are periodically showing up) as well as African violet and, lettuce, basil... My HPS sodium light in a horizontally hung "sun tube" is great in my little vestibule room between living room and outdoor but it's so extremely bright, I have to turn it off at dusk because the neighbors would go bat guano otherwise, over the obnoxious glare totally illuminating my whole yard and them in their nice hot tub... However, I can't leave plants in there because being a vestibule connected to the outdoors, it's getting very cold in there at night. Right now it's about 20 degrees here, so the vestibule is probably about 40. I didn't foresee this, and I don't have an outlet in that room or other easy way to warm it safely when the HPS lights aren't on.... during the day, the cord for the lights is run through the interior door cracked open which is not ideal. Any ideas? How to warm a small vestibule/ entryway room which is light filled and perfect for plants except COLD! Has no outlet, just a ceiling light, and prefer not to drill holes in walls

Can you put up blinds in the windows in the vestibule to block light from escaping? You'd have to remember to close them after dark every night.

Otherwise, can you manage to get an oil-filled radiant heater into the space? Some of them come with thermostats that are mostly sort of accurate enough (like within 5 or 10 degrees) to keep plants alive.

I grow leafy greens under t8s. The lumens per watt from daylight bulbs at Home Depot 85.9. T5 - 86.1 lumens per watt. this is why I went with t8s. I figure by the time these need replaced, LEDs will be half the price and better. T5s are for people that need tons of light in a small area. Most photos I see of t5s in use, have the light hanging a foot or two above the plants so the light can spread out. Seems like a waste.

Ps. If I want tomatoes to fruit, I may need to add a cfl, havnt gotten that far yet.

Just took a look at my grow area, my best growth seems to be under an led shoplight. I picked mine up at Costco for $40. 38 watts at 3700 lumens. 4100 k. Spectrum isn't the best, but it works. When I tested the lux (not the best light test but it is decent for a hobby grower) I was getting about 7000 lux from the led and 4000 lux from the t8.

So, a double t8 fixture (32 watt x 2 and 2700 lumens x 2) consumes 64 watts and gives off 5400 lumens but the 38 watt, 3700 lumens led out performs. I assume this is because LEDs are directional and fluorescents are not.

Flourescentt are only a few weeks old and are 4500 k.