lol, some of the questions here are odd. Akpsdvan, do your calculations please. Assuming the gravel will displace 1/10 of a cubic foot (gravel generally weighs approximately 100 pounds per cubic foot), the additional increase in resin height of 2.1" on a 54" tank, that will have no affect on wether the resin will exit out the top of the tank during backwash. Seriously, if you dont like my comment on the turbulator, keep it to that. Unless you know your calculations, a 10" diameter tank has a .045 cu. ft. capacity per inch of height, and before someone says something absurd, the gravel height will be approximately 4", plenty enough to cover the lower distributor, the gravel displaces the resin from the domed portion of the tank which would have to be figure as a sphere, not a cylinder. The calculation for that is .9 Cu ft for the dome for a standard 10" tank.
Re:the turbulator, they are not bad, just completely overstated in their ability to remove iron or other contaminants from resin. If they worked even close to their stated ability, upscaling them to larger commercial systems would be a high priority. Obviously, nobody is going to invest in the tooling up a 1-1/2" turbulator for a market that does not exist. I have worked on enough of them to know there drawbacks and there advantages. When speaking with the engineering team who develop these, even they admit they are more of a marketing item than a functional one. That being said, I am all about marketing. I develop and sell Alkaline filtration systems, hydromagnetic water conditioning modules, ALkamag filters, and I do the marekting for our overseas office and we make wild and ridiculous claims about the health benefits of the miracle filters we sell. in the US market, we can only market to the truth so no health claims are allowed. I know marketing, and the turbulator, while it has no disadvantage other than cost and complexity, it has very little true benefit. A little citric acid in the brine tank every 6 months is the cheapest and best solution to keeping resin clean.