Hydroasis carries a wide variety of Metal Halide (MH) and High Pressure Sodium (HPS) Replacement Bulbs. We also carry a great selection of specialty gardening bulbs, with enhanced output and color for plant growth. Metal Halide Grow bulbs and High Pressure Sodium Blooming bulbs  belong to the HID (High Intensity Discharge) family of lights and are used for garden lighting because of their high light output per watt and their spectral distribution of light. 

HID bulbs are system specific and should be burned in the fixture that they are designed for. Except for  conversion bulbs, MH bulbs  can only be burned in a Metal Halide fixture and HPS bulbs  can only be burned in a High Pressure Sodium fixture/lighting system of the same wattage.

Metal Halide (MH) bulbs  produce an abundance of light in the blue spectrum. This color of light is excellent for green leafy growth. 

MH Bulbs are available in Horizontal (H)/(HOR),  Base-Up (BU) or  Vertical and Universal (U) burning configurations for optimum performance. The Horizontal and Base-Up bulbs can burn only in these respective positions, while Universal bulbs can burn in any position. 

MH bulbs are available in 175, 250, 400 and 1000 watt sizes.

High Pressure Sodium (HPS) bulbs produce more light in  the orange/red area of the light spectrum - the range that stimulates flowering in plants. They are used for flowering/ fruiting and typically last longer than MH bulbs. HPS Bulbs are all Universal (U), which means they can be burned in any position. 

HPS bulbs are available in 150,160,250,270,400,430, 600 and 1000 watt sizes.

How many watts do you need?

In order to determine the wattage of the lighting system to use,  you must consider the size of the growing area, the light requirements of the plants you're growing and whether HID light is the primary source of light or a supplement to natural light.

*HID Lighting is the Primary source of light
**HID Lighting is the Supplemental source of light

How often should you replace your HID light bulbs?

HID bulbs will keep your plants productive only as long as the light intensity remains strong. It's a good idea to monitor light intensity periodically with an accurate light meter. When lamp intensity has decreased, replace the bulb. A good rule of thumb: both halide and sodium bulbs should be replaced after 12 months of use if the bulb is used for 12 hours+ a day.

Lighting Terms

Lumen is a measurement of light output. One Lumen is equal to the light emitted by one candle that falls on one square foot of surface located one foot away from the candle. 

PAR Watts While the lumens measurement is based on the sensitivity of the human eye to light, PAR Watts objectively measure the total watts of Photosynthetically Active Radiation (PAR) emitted by the bulb. It accounts for the nutritional value and is a direct measure of light energy available for all-important plant photosynthesis.

Color Rendering Index (C.R.I.) is a measure of lighting quality. It is measured on an index from 0-100, with natural daylight equal to 100. Bulbs with a high color rendering index make objects appear more true to life.