Lighting Questions

Low intensity light is fine in the very beginning (until the plant grows its second set of leaves). You are not getting the maximum benefit until your plant is in a similar environment to what it will be flowered in. I suggest keeping a light period above 18 hours. For the fastest transition to full growth, I would leave the grow light on 24 hours.

Not everyone needs one, but the more tools you have the better your knowledge and in turn, results. If you buy a light meter always check the lumen output and write it on the box when you buy a new bulb. That way you can take a reading every 6 months to gauge when to replace the bulb for a newer, more efficient one.

Digital lighting has given the indoor gardener a great advantage compared to their old magnetic coil ballast counterparts. The new Digital Ballasts weigh less, run MH and HPS bulbs, use both 120v and 240v, run at cooler temperatures, have a higher lumen output, greater power efficiency, and some models even have dimming functions. The only advantage I’ve seen with the older magnetic ballasts is that the majority of them are still running. If you’re old school, you might even have a Diamond magnetic light still powering a grow.

This helps to ensure the light turns on and off when they are supposed to. You can manually flip your lights on and off, but what if you become sick? Or what if you are away unexpectedly? The light cycle will be interrupted. Light cycle interruptions will adversely affect your plants.

An HID bulb can lose up to 30% of its efficiency over two years; up to 10% after the first year. The spectrum can also change over time, due to the intensity change. A frugal grower might replace their bulbs every two years. A commercial grower will change the bulbs annually. The (type A) overly conscious grower might replace them every 6 months.  (Fluorescent, LED, and Plasma lights, do not apply- these bulbs are good until they burn out.) If you buy a light meter: When you get a new bulb check the lumen output and write it on the box. Then you can take a reading every 6 months to gauge when to replace the bulbs for newer, more efficient ones.

Yes there is! If you are noticing the leaf tips closest to the light are burning then you should raise your light up more although if your room is regularly over 80 degrees, it’s not the light you need to decrease it is the air exchange. Here is a good rule of thumb for light footprints (max lumen benefit). 1000 Watt: 5’x5’ Footprint, 750 Watt: 4’x4’ Footprint, 600 Watt: 3’ x 3’ Footprint, 400 Watt: 2’x 2’ Footprint

Though your hood is made to spread the light footprint, the most intense light is still in the middle.The simplest solution is to move the plants around to help balance the footprint of light. Move the large plants to the outside and the smaller ones to the middle. You can also purchase a light mover. I do not recommend having the light mover move more than 18” in each direction (over 18” in movement and your max benefit of light dwindles).

Different ballasts can have varying temperatures depending on the design. Some of the newer ballasts are air cooled so that they will always run cool. If your ballast is running higher than 150 degrees, you might need better air exchange around the ballast to keep it cool (so that the equipment does not become damaged).

18-24 full hours of light is best for seedlings. You do not need high intensity light until your seedling grows its second set of leaves.

The vibration noise you hear is usually caused by bolts coming loose over time. I would go through and tighten all of the bolts inside and out. The magnetic coil ballasts vibrate during normal operation. You could have loose bolts inside the ballast compartment (holding the capacitor, magnetic coil) or it could just be the hood cover. Magnetic coil ballasts might not be as efficient as the digital lights, but they do last a lot longer.

The maximum light spreading benefit a light mover will bring to you is 12-24”. Anymore movement than 24” and you’re just diluting the light over a longer distance. I believe light movers bring a higher yield (although not a huge difference but enough to notice). Light movers will also safe guard you from hot spots.

The white haze is due to the color of the gas. The metal pieces are residual parts of the MH bulb and are very common. If the bulb lights up with no flicker, you’re fine. If the bulb flickers or cuts out, take it back. Before you take it back (if you can), try to spark the light with another ballast to ensure it is the bulb and not your ballast.

Clean the glass monthly. The glass already decreases the light off the bulb by about 8%. If the glass is dirty the inefficiency becomes much worse. If you have air-cooled hoods with one side of your hood open to the room, try puttin a fabric filter on the open end to keep dust or pests from entering in the hood.

Clamps work well, but they can occasionally slip off when you raise or lower your hoods. I strongly suggest using duct tape. The best I’ve found is the silver tape that stretches (it usually has black writing all over it). If you use clamps, use duct tape as well to ensure long term effectiveness.

Hot spots occur when the light being reflected is unbalanced. This is often caused by the hood being too close to your plants. Some hood types will always create hot spots. I have played with light diffusers, and they do NOT work as well as you might think, at the very best they might decrease hot spots up to 70%. The best solution (other than raising your hood) is to have a fan blowing right over the hot spot to lower the temperature between the plant and the light. A more expensive way to fix a hot spot is to implement a light mover into your system. Light movers work great. The maximum benefit you can get out of a light mover (to keep the maximum light intensity) is a movement of 12”-24”. The ONLY folks that really need Co2 are the ones with a “Closed Room System”. This means you have NO outtake or intake fan. The systems are really only utilized where it is desert HOT. For most of us when we think of Co2, we are really trying to bump up our yield and veg times. But think about this, if your grow room is connected to your living space by the roof; you have a suffocating gas building up where you are.  The one variable that keeps that gas out of your sleeping or hanging area is an outtake fan. What if a bearing fails in the fan, or the motor, or the breaker for some odd reason? I myself have become sick from Co2, just from working inside the room with the lights on. I have seen and read about adverse reactions when there is use of Co2 in warm indoor environments. If you have a room that tends to get warmer than 80 degrees, or if you anticipate your grow room being above 80 degrees when you cut your fans off (to allow the Co2 to build up), be careful! Also, what benefit do you get out of Co2? You will notice more vegetable matter than potency. So if you are growing botanicals think about that. Lastly, Co2 is ultimately a matter of style and desire. Keep in mind it becomes one more variable to monitor and can possibly harm you if not properly managed. If you feel the gain is worth the management, then give it a go!

Think of this: in Alaska, growers have the advantage of a 24 hour natural light for a month or two straight. The growers I know from Alaska love this time because they could take twice as many cuttings as in the late summer when the cycles swing back. So 24 hour light obviously works. But for best results over an extended period of time, giving your mother 2-4 hours of darkness ensures healthy tissue production (which means hardy clones).

A good rule of thumb is a minimum of 18 hours of light to keep your plant in the vegetative growth state. I would strongly suggest using a 24 hour light cycle for the fastest vegetative results.

Here is what you can do to control heat because of your lighting: Are you using air cooled hoods? Not everyone needs them- if you have a 12 foot ceiling you are blessed. In my opinion air cooled hoods are well worth the extra cost. If you want to have the best possible efficiency buy an air cooled hood AND a hood cover. Check out Hydro Innovations Heat Shield Reflector Hood covers. I’ve seen these covers drop the temperature in a room already air cooled (with hood and insulated ducting) by 8 degrees! Is your ducting Insulated? If you have non-insulated ducting (the silver stuff, single layer), and it runs in lengths longer than 5 feet, you are losing most of the heat right off the ducting. You can actually feel the heat that emanates off the non-insulated ducting. If you run ducting at ALL, you must use insulated ducting. Put in the extra dollars, since you are already putting in the effort, and see 75% better efficiency! Is your ducting running efficiently? Every time you add a 45 or 90 degree angle, the air flow is dramatically decreased. Run your ducting in as straight of a line as possible to maximize efficiency.

It depends. If you have another fan bringing fresh air into the room with the correct CFM rate then you will be fine. If you need your “grow light” fan to keep the air movement optimal, then I suggest running it all of the time. HERE IS A RULE OF THUMB FOR AIR MOVEMENT: If you do not know what the CFM rating is, (you need this for the correct air exchange) use this method: Multiply your room length by the width. Then, multiply by the height of the room. This is your air volume. Divide the air volume of the room by the CFM rating on your fan. You want a complete air exchange atleast every 5 minutes.

If a power outage occurs a few times during a cycle it will not cause a dramatic difference. TIP: In your Mother room you never want the lights out for too long. Buy an LED light with an emergency battery backup. Place it high up in the Mother room. If the power goes out the emergency units sense the power interruption and will turn the light on until the power is restored. Some of these emergency power light backups can run for up to 2 days (or until the battery dies). The great thing is that the power is usually not off more than a few hours. Once the power is on the emergency light units will automatically recharge the battery in the unit.

In defining how bright something is, we have two things to consider. 1. How bright it is at the source- where the light is originating. 2. How much light is falling on an object a particular distance away from the light. Foot Candle: Why Candle Foot? Well since we are in the USA, its more patriotic to use the Candle Foot vs. the Lumen (they are both essentially the same thing). Here is a good example. Get a cake candle. Grab a ruler or tape measure. Stick the candle on one end of the ruler. Light the candle. Turn the lights out (so that the room is dark). One foot-candle of light is the amount of light that candle generates one foot away. That’s a useful unit of measurement. Why? Say you have a light bulb. You are told it produces 200 foot candles of light. That means at one foot from the light bulb, you will receive 200 foot candles of light. But here’s where it gets tricky. The further away you move the light from what you want to illuminate, the less bright the light appears! If you measure it at the light, it’s just as bright. But when you measure at the object you want illuminated, there is less light! LUMENS is a unit of measurement of light. It measures light much the same way. RADIANCE is another way of saying how much light radiating from the light itself. The heat is usually measured. ILLUMINANCE is what results from the source of light. ILLUMINANCE, is when you shine a light in a dark space therefore lighting the space up. ILLUMINANCE is a measurement of the total light being seen in the dark space. LUX, is the metric version of ILLUMINANCE. Candlepower is a rating of light output at a bulb source, converting with English measurements. Foot-candles, is a measurement of light on an illuminated object. Lumens is he metric equivalent of a Candle foot. Divide the number of lumens you have, by 12.57 and you get the candlepower equivalent. LUX is the metric version of ILLUMINANCE.