Regarding T8 lighting...

[garysan]

I'm in the process of building a rack to house the growing collection and have zero'd in on a good, solid, metal rack with chipboard shelves (plants will be grouped together in shallow plastic trays to avoid damaging the shelves with water and to aid removal for watering, checking, etc.)

The rack measure 1525mm wide by 455mm deep and I'm looking at maximising light by fitting either a pair of single or a pair of double 5ft t8 fittings on the underside of each shelf (will likely do this one shelf at a time as and when needs must so I can monitor heat and airflow on each shelf before populating it with new plants). They'll also be a fan at each end of each shelf blowing across and most likely, a humidifier or two perched on the top feeding outlets along the length of each shelf to keep humidity up around 60%.

My question is this, I've seen lots of different fittings available with varying wattages and overall lengths; some of which extend beyond the 1525mm of the shelves and others which fall just inside that (don't want them extending beyond the width of the shelves TBH). What sort of tubes should I be aiming for? Do we use specific gro tubes or is it just getting the colour temp right? I realise I'm perhaps over simplifying but would appreciate some guidance. I'm in the UK so please bear than mind when pointing me at Best Buy or Home Depot....

 

[naoki]

Isn't 120cm (4ft, 32W) the common length in Europe? Since you'll need to replace bulbs, it is good to go with the common length (usually cheaper replacement). It should work for your shelf. The edge might be a little dimmer, but they usually don't have a sharp cut-off.

When you are going with T8, you might want to pay attention to the reflector. With T5, they usually seem to come with recent reflector. But quite a lot of T8 shop-lights have minimum reflector, so it waste lots of light.

Some of the purple plant tubes do seem to have higher efficiency. If you can get them cheap, it could be worth going with it. In my opinion (from some casual measurement), anything between 3000-6500K is probably good enough. Some people like so-called "daylight" bulb, but I haven't seen much advantage of that color.

For the width of the shelf, you'll need at least 4 tubes per shelf.

You might want to check he price of LED shoplight or T8 LEDs. With the recent price drop (at least here), it could be more economical than fluorescent.

If you are going to humidify and the ambient RH is usually low, you might want to consider a reflective grow tent. But I'm guessing that your place has high ambient RH.

I personally prefer metal shelves over chipboard shelves (I'm guessing that it is the kind with unfinished chipboard). Even if you are careful, you probably spill some water. Maybe you can paint the chipboard.

 

[fibre]

Gary, I use two bulbs of T5 HO 850 58W, for a shelf that is about 58 cm wide. The distance of the bulbs to the leaves is from 20cm to 40 cm. At the first time I used reflectors with every bulb but this construction proofed to be much to bright! So I removed the reflectors and evan one of the two bulbs at some shelves. Only P. niveum and P. helenae grow under T5HO with reflectors now.

 

[garysan]

All good advice - thanks.

Racking arrived this afternoon OMG it's sooo heavy. Will put it all together over the weekend and then take some detailed measurements (and figure out how to mount the lighting units to the underside of each shelf/support) before ordering a shelf's worth on Monday

I'm going to write up a proper collections/build thread I think to keep all this info in one place.

 

[phraggy]

Hi Gary. I know this is quite expensive but for my greenhouse set up, which also has lights for the winter months, I use the fittings and lights used for aquatic plant growth. which are obtainable upto 18000k. Worth having a look if there is a shop in you vicinity. For extra reflection you could always use tinfoil (or such ) on the underside of the wood.
Sorry I missed you at Harrogate.

Ed

 

[naoki]

Ed, corals (or zooxanthellae in there) have quite different photosynthetic action spectrum:

Compare that to that of land plants (this is based on bunch of full sun crop plants, see the red line):

That's why those aquarium fluorescent lights has high K (blue). The florescent bulbs for aquatic plants (purplish ones) don't have high K (I'm sure yours for aquatic plants are this kind). You can use high K for orchids, but it is pretty wasteful, and there is no point of using something with heavy blue peaks.

 

[troy]

T8s I've got 5 plants in bloom and 3 more that may or may not

Cost me 20.00 per light fixture with full spectrum bulbs, I am currently using only 1 bulb in each fixture

 

[phraggy]

Ed, corals (or zooxanthellae in there) have quite different photosynthetic action spectrum:

Compare that to that of land plants (this is based on bunch of full sun crop plants, see the red line):

That's why those aquarium fluorescent lights has high K (blue). The florescent bulbs for aquatic plants (purplish ones) don't have high K (I'm sure yours for aquatic plants are this kind). You can use high K for orchids, but it is pretty wasteful, and there is no point of using something with heavy blue peaks.

Thanks for the info naoki will make the adjustments. Ed