I've had several people ask about how my DIY air separator works, so here is my attemp to explain it.
My CSD tank is in the room upstairs above my DT, making it about 8' above my DT. When I first connected it strait into my DT, it would push very large bubbles into my DT at the beginning of each surge. The falling water from my surge tank would basically force all the air out of the empty pipe and push it directly into my DT. Having your CSD tank 8' up gives you a really good blast of water into your DT, but it also has more air in the pipe to empty out on the way down. The large bubbles at the beginning of the surge would cause a lot of water to splash out above where the CSD water enters my tank. Anyone with familiar with a CSD probably knows this well.
I decided to try an air separator to take out these large bubbles and it worked even better than I had hoped. I no longer have any large bubbles splashing into my DT at all. Very small micro bubbles still however make it all the way through. The micro bubbles are not a problem at all and the salt spray/creep is now almost nonexistent. (my tangs splash out more water) It's basically the same idea/mechanics that most large commercial hydronic systems use. I just adapted it to fit my tank.
Here is my primitive hand drawing of my air separator.(sorry, don't have the fancy CAD on my puter)
The larger the diameter of the separator, the better it works. The idea being that the water will travel slower through a larger tank/pipe, giving the bubbles more time to rise up and out. I built mine out of 4" and 6" PVC pipe. I would have prefered to use larger diameter pipe, but it would not fit between my DT and the wall. I also went as tall as I could possibly make it, going from the bottom of my cabinet to the ceiling.
I used a hot air welder to build parts of mine, This was specifically to make it fit in a really tight space. Someone could certainly make one using glued fittings, if they have the room, and they aren't familiar with using a hot air welder.
The 1" check valve at the top was added to keep air from rushing back into the vessel. For some reason air would get pulled in through this vent and spray bubbles into my DT at the end of each surge, without this checkvalve.
I ran the "air vent" with a hose down into my sump, above the waterline, just to be safe. Although it does not flow water, it does carry alot of moisture.
I've once had a large Mexican Turbo crawl into the pipe where the water enters my DT and block the flow of the surge. He was strong enough to hang on, forcing the surge water to go all the way to the top of the separator, into the drain hose, and into my sump.
Was soooo glad I had decided to run that hose.