if your staff is getting competitive, then that means they are aware of what others are making. This is a good thing in terms of trying to set up a "pooling" system, and more importantly, for motivating your employees. Having said this, when dealing with someone's money, never ever ever touch it without talking to the them first. If you make a change to how people earn their money, you are messing with their livelihood, and this will blow up on you.
I assume you are talking about your bar tenders, and not the wait staff. i would suggest sitting the bar staff down and ask them how they think they can best resolve the competitive, and therefore deleterious, spirit that is evolving.
Competition can be one of the most incredible, natural motivators for human behavior. It's not about money per se, but about winning...whatever that might be. Perhaps you can creatively use this natural motivator to your advantage?
For example, lets say you decide to try pooling tips. For some, this can drive the wrong behavior, say someone being lazy and skating. So, perhaps you can do something fun, and create a competition for pooling. For example, ...whoever puts $X in the tip pool first, does not have to X items of 'side work'. The one who contributes the least, has to do more of the 'side work'. Natural deterrent, natural motivator.
Most of the major restaurants and bars in the states pool tips, however, we can all agree human behavior and what motivates people is different from one country to the next. For this reason alone, not to mention just good basic people management, ask for feedback. Point out the concern you are seeing, and ask your all-adult staff how they think best to solve it.
It is, according to my experience, customary for wait staff to tip out the bar, and for both wait staff and bar staff to tip out the kitchen. The percentage has varied. Ask the team what they think is fair.
just my two cents