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Fire Pit Media: Lava Rock & Fire Glass

Everything you need to know about fire pit media!


Media takes the place of traditional wood logs in a gas fire pit and is used to create a natural flame appearance.

If you’ve ever looked at a gas fire pit burner without media, you’ve probably noticed that the flames are concentrated to areas where the gas exits the burner, rather than being dispersed throughout the burner area. But, once media is added, the flames are distributed evenly and look very realistic.

This is because media helps to distribute the gas flow from the burner, creating a natural flame pattern while disguising the burner and pan from view. Fire pit media includes lava rock, fire glass, ceramic gas logs, fireballs, and river rocks.

wrench icon Pro Tip:

DO NOT use regular stones or river rocks in your fire pit. Regular stones may contain water that, once heated, will produce a build-up of steam and cause the stones to explode.


Typically, with proper gas pressure, media should only cover your gas fire pit burner by one-inch. The placement of media can vary from burner to burner, so make sure to check your owner’s manual for the correct depth and amount to use.

For example, If you're using a burner with raised jets, like a Torpedo or Bullet Burner, you'll cover only the burner tube with media and leave the jets exposed (the media can sit flush with the jets, or the jets can stick out a little above the media).


Lava rock is an organic material that’s naturally formed from volcanic magma. As the magma cools, trapped gases are released and burst through the surface, creating lava rock’s signature porous look.

Due to its volcanic composition, lava rock is guaranteed fire-safe, can withstand long-term exposure to extremely high temperatures, and is completely maintenance-free.

Lava rock is a naturally beautiful filler for fire pits on its own, but it can also be used as a base for more expensive fire pit media, such as fire glass and river rocks, to save you money.

Since it’s an organic material, the size, shape, and color will vary from batch-to-batch, so if you’re going for a uniform look throughout your fire pit or fireplace, it’s best to buy lava rock in bulk up-front.


For safety reasons, always wear a pair of sturdy outdoor gloves while handling lava rock and be sure to check your owner’s manual before getting started:

  1. Pour lava rock out onto the ground to remove dust particles and broken bits (dust can clog the burner ports and will negatively affect burner performance).
  2. Pick up individual pieces of lava rock and place them into the fire pit, starting with smaller pieces for the first layer and adding larger pieces on top.


  1. Follow steps 1-2 above, but this time only fill the lava rock up three-quarters of the way.
  2. Top off with a layer of fire glass or river rocks.


Lava rock is porous and will absorb water if it gets rained on. Turning your fire pit on high while lava rock is wet will cause the water inside to boil, leading the lava rock to pop or potentially burst.

Here’s what to do to use your fire pit safely, if your lava rock is wet:

  1. Turn the fire pit on low for approximately 15-30 minutes to safely burn off any water (If you live in a naturally humid area, you may need more time).
  2. Once the fire pit has been on long enough for the lava rock to dry, slowly turn the gas up until you reach your desired flame-height.
  3. Enjoy!


One way to prevent your media from getting wet is to keep your fire pit covered when not in use. Covering your fire pit will also prevent unnecessary damage from daily exposure to the elements, ensuring it stays in good working condition.

In some cases, not using a cover may even void the warranty of your burner. If possible, you can always store your fire pit away during the winter or off-season to keep it safe from harsh weather conditions.

Make sure your fire pit is COOL to the touch before covering; otherwise, the cover may melt and ruin the burner.


Fire glass is made from color-infused, tempered glass. Tempering is a process that increases the strength of glass through heating and quickly “quenching”, or cooling, the glass.

Tempering can also be achieved through chemical processing. Both processes create compression on the surface and tension in the interior of the glass, resulting in four times the strength of untempered glass.

Fire glass is tumbled and polished to remove sharp edges, making it safe to touch. It’s designed for high-heat applications, and will never discolor, burn, melt, or produce toxic fumes, soot, ash, or smoke when used properly.

Fire glass generates more heat than gas logs and lava rock and will radiate 3-4 times more heat with its reflective surface, making it more efficient.

wrench icon Pro Tip:

DO NOT use regular, untempered glass in your fire feature. Regular glass can pop or burst, sending sharp shards flying through the air.


Fire glass is available in small, medium, and large sizes, along with an array of color options. Sizing isn’t always consistent throughout a single batch of fire glass, and you may find that you have a mix of small and large pieces.

You have a choice between accent, reflective, and smooth glass.

Accent Fire Glass

Accent fire glass is made up of smaller, non-uniform pieces of glass that are chipped off large glass bricks, then tumbled to remove sharp edges.

It’s recommended to be used as an accent on top of larger fire glass. You can use a single color or mix and match colors to create a unique look that fits your personal taste and outdoor decor.

Reflective Fire Glass

Reflective fire glass features a mirror-like finish and intensified coloring. Both sunlight and flames dramatically reflect off the mirror-like surface for a gorgeous display both day and night.

Smooth Fire Glass

Smooth fire glass consists of smaller, irregularly-sized glass pieces with polished edges that resemble marbles or jelly beans. The coloring is consistent throughout with a slightly translucent finish.


Compared to lava rock, fire glass can get pretty pricey, depending on how much you need.

To get the fire glass look without the added expense, you can use lava rock as a base layer, then place fire glass on top, effectively reducing the amount of fire glass you need by half to fill your fire pit.

Using lava rock as a base layer will cause some soot build-up on your fire glass, as well as using liquid propane gas as your fuel source.

To avoid a sooty appearance, choose darker colored fire glass. If you plan on going with a lighter color, you’ll need to clean the fire glass periodically to remove any soot (see below for cleaning process).

Instead of using lava rock as your base layer, you can always start with a layer of less expensive fire glass, such as a clear color, then top it off with your choice of colored glass.

This won’t reduce the cost as much as using lava rock, but it will prevent soot build-up and save you from having to clean your fire glass.


For starters, fire glass can break, so make sure you wear gloves during the entire cleaning process to protect your hands from sharp shards:

  1. Remove the fire glass from the fire pit and place it into a bucket of soapy water. Wash clean.
  2. Rinse off soap with clean water.
  3. Lay the fire glass out on a towel to air dry.
  4. Place the dry fire glass back into your fire pit.
  5. Enjoy!


  • Fire glass and lava rock should only be used in gas fire features fueled by Liquid Propane or Natural Gas. Never use either media in a wood burning unit.
  • Never place another type of fire pit media on top of fire glass. Doing so can cause damage.
  • The bottom layers of your fire pit media will continue to radiate heat even after you’ve turned off your gas fire pit. Only handle media after it has cooled completely.
  • Although some soot build-up can occur on fire glass, especially when used with Liquid Propane, an excessive amount may be a sign that your air mixture is incorrect. Soot build-up is never a result of the media. You should contact your installer to verify that your unit is burning cleanly and efficiently.
  • Your gas fire pit should be properly ventilated on at least two sides. If heat gets trapped inside the fire pit, it has the potential to crack or melt your fire glass. Contact your installer if ventilation or heat build-up is a concern.
  • Make sure to keep your fire pit covered when not in use to prevent moisture from entering the unit. Heated water, even condensation, will cause a build-up of steam, which can negatively impact the performance of your media and even lead lava rock to pop or burst.
  • If dropped, fire glass has the potential to crack or fracture, creating sharp edges. Always use caution when handling your media and be sure to wear a sturdy pair of gloves.


Do you have more questions for us? Call our NFI certified experts at (800) 919-1904 today!


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