Quote from talontrading:
1. Dark pools are used for large customer orders. I sat on an institutional trading desk for a while and I know that we got better executions in the dark pools than we did in the open markets. It is only a question of whether there is someone in the dark pool wanting to take the other side of the trade. We were the CUSTOMER, the PUBLIC... dark pools are not some scheme designed to take money from the customer.
And achilles... who probes the market with a "large order" like you suggest?? Don't you probe with a small order? Like between the bid / offer to see if there's selling interest there?
Retail investors can access this liquidity and this information... it's not something special that no one can access. Again, I know this is true from experience.
gee... here's another thought: it's also possible for people to hide some of their order. For instance, you could enter an order to buy 100K of something on Nasdaq but only show buying 500. Maybe everyone should have to display full size on every order? Well if that was the rule wouldn't you just break the 100K up into 500 share lots yourself? In that case... we need a new rule saying that you have to enter the whole amount you want to buy / sell all at once. Then maybe I'll just wait until tomorrow to do some of it? Ok... then we need a new rule saying a trader can only enter an order once a week.
Do you see where this kind of idiotic intervention goes? You have people who don't understand the mechanics of markets (the vast majority of ET readers also fall here btw) trying to make rules. This cannot end well. Markets are not and never have been fair. That's an illusion. Realize if you want to participate you are playing against a stacked deck and deal with it.
FYI, I pop on ET once every few years and usually get irritated and go away within a few weeks. Just so you know what happens when I vanish! 
You agree equity markets are rigged, then act like nobody gets screwed. Which makes your argument (that it's all roses!), nonsensical.
By definition, when any game is rigged, one side is favored over the other. So which side is favored? And which isn't?
I'll take the time to answer that question.
The side that has access to and employs dark pools and HFT has a discernible advantage over the side that does not.
You may have worked for a large Pension Fund (aka "The Public"), as you say. But Not All Pension funds are Large, or have the resources to capitalize on HFT or Dark Pools. So, in that case, your Large "Public" Fund, would screw the smaller, less capitalized "Public" fund. Or, in reality, many of them.
You don't understand my point about large order probing or HFT. A large order (institutional size), gets broken into smaller pieces, which are still LARGE relative to volume sitting on the bid/ask. How it relates to HFT: large orders can't probe the market successfully, because HFT seeks hidden volume (market orders) and front-run it. The Big Guys can't get use limit orders for Big Orders. Retail will front-run that. And market orders broken into pieces (FOR BIG ORDERS), get front-run by HFT. So Dark Pools are used. Get my point?
You say that Retailers can access Dark Pool liquidity and T&S information? Could you please tell us where we can find that info?
The difference between ice-berg orders on the Naz and Dark Pools - hidden orders on the NAZ get front-run by HFT!!! There's no HFT in Dark Pools!
So, once again, the Big Guys trade in Dark Pools, so they don't get caught by their own traps laid to ensnare small traders.
It's okay if you get irritated, btw. I don't really care.
