A bong stem is a water pipe addition through which the user increases the bubbling inside the bong and/or adds an extra water pool to the bong for better smoke filtration. A bong stem can be an ash catcher, a diffuser, downstem or even a bowl. Each of them is an addition to your water pipe, each of them having a different role in providing that cool, crissp, smooth hit you are dreaming about.
The most powerful bong stems are the ash catchers. They are known as bong precoolers because they connect on the outside part of the bong and are precooling the smoke before getting into the water pipe's water pool. In general an ash catcher has more diffuser slits then any other bong stem and they also have the capacity to retain any resin or tart from getting into the bong thus a user will maintain a cleaner water pipe for long periods of time.
The downstem is not a bong precooler is a bong stem and it slide into the bong's water chamber where it increases the number of bubbles, mixing the smoke with the water for additional purification. The more diffuser slits a downstem has the more bubbles you will get.
The ash catchers also known as bong precoolers come in different shapes and designs but all of them have two main goals: add an extra water pool to your bong where the smoke will be purified for the first time and prevent ash, herb leftovers, resin or tart from getting into your bong. What is important when buying an ash catcher is the number of diffuser slits it has since this number affects the bubbling inside the water pool. The more bubbling you get the more purified and smooth your smoke will be.
In this picture we connected an eleven arm tree ash catcher to the water pipe and added a glass bowl on top (where the herb is placed). The eleven arm tree ash catcher is one of the most powerful bong precoolers due to its 33 diffuser slits and its ability to catch the ash and prevent it from getting inside the bong. The 18.5 mm glass on glass connection piece slides inside the bong. On top place the glass bowl. When the herb is lighted the smoke will travel through the ash catcher's water pool and then move into the bong's water pool so the user will have a double smoke filtration system.
A downstem is a bong addition design to increase the bubbling inside the bong's water pool. However a downstem can also be connected to some ash catchers thus will increase the bubbling in the ash catcher's water pool too.
Downstems come in different shapes, sizes and prices but like in the case of ash catchers the number of diffuser slits counts. The more the better. Unlike ash catchers, downstems don't have the ability to retain ash from getting inside the bong chamber, they are designed only to increase the bubbling inside the bong's or ash catcher's chamber.
In this picture we connected a six arm downstem to the water pipe. On top of the downstem the glass bowl is placed. The six arm downstem is one of the most powerful stem on the market because it has 6 arms, each arm having 3 diffuser slits. 33 diffuser slits working together to mix the smoke with the water for a perfect, crisp and smooth hit. See more about the six arm downstem by clicking the link.