When and why to replace the Indoor Lamps
In indoor cultivation, the power and quality of your HPS lamps in the grow box are extremely important factors that significantly influence the results and performance of plants in terms of number of flowers and final fruit yield. They can really make a difference! As also happens during the life of a human being who ages with time, the light from high pressure sodium discharge lamps or metal halide lamps that are used continuously gradually become less effective over time and must be replaced at the moment. quite right.
Knowing exactly when to change your indoor lamp is the key to keeping your grow lighting at a light level that is as bright as possible. It will benefit the health of your plants and the final harvest they will return to you.Read the rest of our article if you want to know how to find out the most effective method for judging the decreases in light intensity of indoor lamps and the reflectivity of the reflector in the grow room.
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Hydroponics: how much harvest do you lose with your lamps?
If you are using high-pressure sodium lamps for the flowering phase or metal halide lamps for the growing and cutting phase, understanding when to replace is essential. How often should the grow light be replaced? Every 6 months every 12 months or at the end of the plant's life cycle?
Ultimately this is the total time they have been on, as usually all growers turn on the lamps for a different number of hours in each grow cycle in the grow chamber.
The yield of hps lamps in grow boxes
The Yield of High Pressure Sodium HPS Lamps
High pressure sodium HPS lamps produce in their efficient emission phase a light with a red / orange spectrum which is ideal in the flowering phase for obtaining flowers and fruit in abundance. To replace a discharge light, you must always consider the number of hours it has been operational and not the number of cultivation cycles in which it has operated.
The reason is that every grower manages the hours of their indoor lighting differently, for example:
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Grower A chooses to grow 4 large plants in a 2m x 2m x 2m grow box with 4 HPS discharge lamps. Grower A keeps these lights on for 18 hours a day in the vegetative phase for 6 weeks and then switches to the flowering phase with a 12 hour cycle for 10 weeks. In this case, a complete crop cycle will reach 1569 hours.
Grower B will use the same grow room and the same number of 400w lights, but will focus on 12 smaller plants instead of Grower A's 4. Grower B will follow an 18 hour vegetative cycle for 2 weeks to switch to flowering with 18 hours of light for 8 weeks. In this case the complete crop cycle will reach 924 hours.
The example shows us that 2 crops can have very different cycles, it is therefore necessary to adopt a separate strategy based on the choices of the grower and the type of plant.
After 12 months, Grower A will have completed 3 crops and Grower B will have completed 5. Both will keep their lamps on for approximately the same number of hours:
grower A - 3-crops x 1596 hours = 4788 hours
grower B - 5 crops x 924 hours = 4620 hours
This supports the thesis that in order to evaluate the lamp replacement times, it is necessary to understand how many hours it is used.
By evaluating the published data of one of the most famous high pressure sodium horticultural lamps, the Sylvania Grolux 600W AGRO, it can be seen how during the first 6,000 Hours of use the total light output (which tells us the stability of the lumens) , drops by 1% every 1000 hours of lamp use. In our Example the 2 growers will lose about 3-4% of the yield
So how often should hps lamps be changed in indoor growing?
Ay Hydroponics.eu we recommend changing the lamps every 4000-5000 hours
Yield of mh metal halide lamps
MH Lamps are very different from HPS. In fact, metal halide lamps produce a spectrum of blue light and are very suitable for the vegetative growth phase of plants.
The lumen output of this type of lamp decreases over time much faster than an indoor HPS lamp. If an HPS lamp drops by 2% after 2000 hours of use, an MH lamp will drop by 9%!
As can also be seen from the graph, the reduction at 4000 hours is 15% for MH and 4% for HPS.
The question is: How often should MH lamps be changed?
If you are using metal halide lamps exclusively for vegetative growth and changing to a HPS at the beginning of flowering, you need to change them every 2000-3000 hours of operation.
The graph shows how the luminous flux yield varies for both Sylvania HPS and MH after 8000 hours.
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How much do the reflectors make in the grow box?
When it comes to indoor lighting kits, reflectors are also very important. They help reflect light from the top and sides. If the reflector has an acceptable quality they could guarantee 50% more light than a lamp alone.
The problem with reflectors is that over time and through exposure to the heat of the lamp, these reflective surfaces begin to slowly oxidize resulting in a significant drop in reflection.
From the data of Gavita Holland it can be seen that aluminum (even if of high quality) will lose about 1% of reflection every 1000 hours of exposure to the light of the lamp in the greenhouse where the environment is clean.
In the case of the grow room the situation is a little different because in this case the environment would not be so clean. In grow boxes, the spotlights end up near the plants and are often covered with dust and dirt (foliar sprays, etc.). For growers using humidifiers or nebulizers, this problem increases enormously. Using a humidifier with tap water will form a white dusty deposit on most of the equipment in the grow room (and also on the leaves) due to the calcium in the tap water and unfortunately all of this makes the reflectors not very reflective.
After 12 months in a clean grow box it can be expected that the reflector will lose about 5% of its original yield. In the presence of a humidifier or using a vaporizer the loss can be up to 10% or more! A 10% loss of reflection translates into 5% less light.
The solution if you use a humidifier is to install a reverse osmosis system to filter the salts and generate pure water. The second thing to do is to clean the reflector with a soft microfiber cloth to remove the patina that has formed even if it is really impossible to return the reflector to its original state.
Experienced growers keep this reflector problem in mind and replace it every 12-18 months or so, although amateur growers usually do not replace it as often due to smaller budgets.
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