Play with the water level. It's not milking as good as it should (assuming you have a diffused downstem). When I got my RooR beaker it took a while to find the right level. Starting at :12 your bubbles are too rapid. Start with the water right below the bottom where the joint meets the beaker. Inhale with bud in the bowl -BUT DONT LIGHT - and you should see the bubbles come to the surface, rest on the surface for a moment and then "pop." You may have to slow down your pull considerably as well as fluctuate water levels. Once you have that dialed in light the bowl and enjoy!
This guy has it PERFECT before he lights the bowl:
:35 - Notice how the bubbles are slow and they sit on the surface for a moment and then POP compared to how rapid your bubbles were.
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When you get it right that smoke will build in a concentrated "ball" in the beaker. Watch out! That Illadelph is going to hit like a champ!
I feel it could be a little smoother if you could build the smoke more efficiently and light the bowl without using the lighter for :12. You should be able to light the bowl in a second and tamp the bowl with your finger to ensure smooth even burning. Besides destroying the THC by roasting the bowl; the butane taste alone would have ruined the hit for me - I use a ceramic tipped soldering iron because it allows me to light the bowl without butane taste and I use the end of it to tamp the bowl so that it burns smoothly / evenly.
Notice how your smoke seems to fill the bottom chamber almost immediately with thin pale smoke @ :05 and gradually gets more "milky" as you pull; reaching a full milk at :13? It tells me that you are pulling too fast / your bowl isn't burning properly. Smooth your hit out and get that bowl burning properly and I can promise that you will get better hits.
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The popping of the bubbles is very important because when the bubble pops after sitting on the surface for a moment the smoke is deposited right on-top of the water level and it remains there relatively undisturbed by the slow velocity of the air - until another bubble pops and displaces it upward. Basically it builds smoke directly on top of smoke. This video is not perfect (I only searched utube for 2 minutes) but it shows the smoke "stacking" as opposed to "filling in" like your hit.
[youtube]4SoJbx8KWKM[/youtube]
Which brings us to the water level. You are trying to match the water level to your pull. There is no "right" level - it is preference to what you want a hit to feel like while being able to efficiently stack the smoke. I know and measure EXACTLY how many mL of water I like in my piece to give me the drag I like and get the perfect dense milk. You can maintain low water levels - but you are going to have to pull VERY gently to control the agitation of the water / air / bubbles so they do not pop prematurely and create thin smoke. I'm not saying it can't be done - With low water levels I find there isn't enough resistance / drag to get a slow even hit to a point where the bubbles rise, rest, pop to my liking. Just play with it figure out how hard you want to inhale and then match the water level till you see the bubbles rise, rest, pop. If you feel too much drag - lower the water level and hit softer; if it feels too delicate - raise the water level until it feels right. Once you have it dialed in, mark it on your bong or pour into a measuring cup and remember the volume so that you can enjoy the same experience again.
Feel free to ask any questions. I am more than willing to answer any question(s) that will help enhance your smoking satisfaction.
wish I had a bong,,I bought one,,used it twice,,set it down,,and the bottom cracked all the way around,,it was then I figured bongs are not for me,,still Zig-Zaggin it,,but nice one Kered