What do you need to know when buying a reflector for your growroom? Well firstly you should know you need one. Light spraying indiscriminately over your ceiling and walls is a waste of electricity, and worse – your plants are being denied a chance to grow to their full potential.
The purpose of a reflector is to channel as much light as possible from your lamps in the direction of your crop. Attempting to grow hydroponically without reflectors is akin to driving a herd of sheep without a sheep dog; or trying to impregnate the wife from ten paces. All theoretically possible but thoroughly improvident and ill-advised.
The ideal reflector will not just redirect light but will uniformly distribute it. It will allow your plants to be sufficiently close to your lamp so as to gain maximum benefit from the light, but will also prevent shadow patterns, hotspots – and a raging bushfire in your growroom. Newcomers to hydroponics might release a disheartened sigh when confronted with the plethora of different reflectors and options available, but fear not – let Uncle HYDROMAG step in to take you by the hand, bounce you on his knee, and tell you that it’s all going to be alright (we have been CRB checked, we promise).
The most obvious points to consider when deciding which reflector to buy are firstly your budget and secondly the size of your growing area. Prices vary wildly (from under £20 to well over £200), and an inexperienced grower may not always benefit from an expensive reflector if his set-up is less than perfect. And different reflectors have different footprints – if you’re planning to grow in a 75cm x 75cm tent, you’re really not going to need Sun System’s Magnum XXXL with its metre-long length. A bit of basic research and some common sense will carry the grower a long way. So, onto the main reflector types:
1. Basic Winged Reflectors
The cheapest reflectors on the market tend to come in this form, as they’re essentially just moulded light aluminium with open ends and low production costs.
However, unlike at Primark, cheap doesn’t necessarily equate to "shit". Even the lowest-priced reflectors on the market these days are generally built out of decent-quality, dimpled aluminium (allowing for a nice, even disbursement of light). They’re also known as "open-ended reflectors" owing to the fact they have just two sides reflecting light downwards, leading to a slight loss of light focus and intensity. This is offset by the fact that this design allows for heat to escape, meaning the reflectors can be placed much closer to your crop without scorching your canopy. Plenty of seasoned growers still swear by such brands as the Euro Wing, ignoring the siren call of more elaborate, expensive suitors.
• Lightweight and versatile.
• Dirt cheap so having to buy replacements won’t hit you in the pocket.
• Heat can easily escape so lamps can be placed closer to crop.
• They’re open ended so a small amount of light intensity is lost.
• Cheaper reflective materials can mean a loss of light and uniformity of spread.
• Some brands are angular and will reflect light unevenly, leading to irregular plant growth and hotspots.
Examples: CFL Hobby Reflector, Euro Wing.
2. Adjustable Winged Reflectors
Sometimes called “Adjustable double parabolic” reflectors, these designs give the grower added levels of control compared with the standard winged design. The king of the adjustable reflectors is the Adjust-A-Wing, and it’s yet to see a lot of competition. Like Oprah Winfrey’s belt, it’s designed for a yo-yoing span. They tend to be particularly useful for large growrooms owing to their exceptional light distribution.
• Modifiable footprint width.
• The colour spectrum can be changed, reflecting the light of different seasons.
• A moveable lamp allows you to make small adjustments to avoid shadowing and hotspots.
• Open-ended so doesn’t trap heat.
• Parabolic curving creates an even diffusion of light.
• Open ended so a small loss of light intensity.
• Not suitable for small growrooms or tents.
Example: Adjust-A-Wing, Powerplant Mantis.
3. Closed-End Reflectors
Breadbox-like in appearance, this design has four sides (as you might have guessed), with the benefit being that the lamp’s light is intense, and focused straight downwards. Heat build-up is the main drawback although certain designs such as Hortiline’s Northstar are built with a “chimney” to negate this effect. The big hydroponics greenhouses tend to use lots of small parabolic closed-end reflectors at a high height (the loss of intensity being countered by the large amount of crossover footprints).
• High light intensity. Perfect for certain plant types.
• Maximum efficiency.
• Less crossover of light with multiple lamps, unless raised quite high or if used with parabolic models.
• Build-up of heat needs attention.
Examples: Gavita Hortistar, Hortiline Nortstar, Sun Mate Grow.
4. Vertical Reflectors
These are reflector designed to hold a bulb in a vertical position. Proponents swear by this system. With horizontal bulbs a good quarter to a third of the light goes straight up into the reflector before passing down again, so could be said to be less efficient than the vertical alternative. Although the light is less intense, this set-up provides a good even distribution of light over a wide area.
• Wide, even footprints.
• More points of light getting to the plants. Less diffusion.
• Mid and lower level leaves more easily reached.
• They’re open ended so a small amount of light intensity is lost.
• Decrease in light intensity.
Examples: Grostar Reflector, Sun King Silver
5. Air-Cooled Reflectors
Essentially a closed-end reflector its own internal cooling system. They’re usually – but not always – sealed with a pane of glass.
The chief benefit of using this system is there’s significantly less heat given off in your grow room, giving the grower more control of his space (although growers should ventilate and cool their rooms already). The lamps can also be placed very close to the plants – perfect if hanging height is an issue. On the flip side this means extra fans, extra ducting, and more vigilance over air quality as there will be a constant flow of it through your reflector. It’s worth noting too much cool air around your bulb will narrow the spectrum and reduce output (particularly so with Metal Halide bulbs), so choose your model carefully.
• Almost no excess heat generated.
• Perfect if there are space / height issues in your grow area.
• Between 3-5% of light gets lost through glass.
• Dirty air will degrade your lamp / reflector sooner.
• Cool bulbs = reduced output.
Examples: Maxibright Gold Star, Silverstar, Growlite OG
Other things to consider:
There are numerous factors to take into consideration once you’ve made your purchase. The first question you’ll ask yourself if how high to set your lamps / reflectors. Regardless of what kit you’ve purchased, you will need to raise and lower your lamps through the course of your crop cycle. Seedlings require much less light than flowering plants, but equally different plant types have different needs.
As with everything in this miserable world, reflectors don’t last forever. You may only get three or four crop cycles of use out of them – something to consider if you’re strapped for cash. The use of humidifiers will likely leave calcium deposits – especially if you live in a hard water area (tip: invest in a Reverse Osmosis machine). Eventually though, dust and deposits will make their presence felt on your reflectors – and they’re near impossible to shift without permanently scarring reflective material. (N.B. Some reflectors come with replaceable plates, saving you from replacing the entire reflector.) Any damage to your reflectors will reduce light intensity and ultimately uniformity of spread. Using a light metre or an IR camera can help you keep on top of this particular problem.
Ultimately the much science understanding behind lighting and reflectors is an ongoing process. Different growers will swear by their favourite reflectors and there’s not much consensus as to which is best. The novice grower is advised to pick what fits your budget, and can sufficiently cover your whole grow area (will you need to buy a second or even third lamp?)
But importantly, you need an even spread of light. An uneven distribution causes an uneven intensity of light over your crops, creating a frustrating Pushmi-pullyu scenario where the lamps are always either too near or too far. Too far and stronger stems will push through above the others – too near and your plants’ leaves will be toast. Use your eyes and learn to embrace the old method of trial and error.