Best opening to force positional play?

Exactly what the title asks, when I'm playing white which opening move or set of moves would be best when trying to play in a positional rather than tactical way? That's the style of play that I'm best at and I'd like to find an opening that would work well.

So far I've had pretty good success with the English Opening but I'm thinking there are probably better options.

Our club recently had top GM Nigel Short visit for a lecture and simul. He was asked what is the best way to improve. His response immediately was to work on your tactics! Your question is thus irrelevant if you want to improve, as I believe you obviously do. By the way it's more fun as well. I currently play sharp openings looking for positions with tactical opportunities. I never however forget to consider the positional nature of the game. Indeed often I win by simply applying lots of pressure then swapping off into a winning endgame! Along with tactics if you work on your endgame you will see a dramatic improvement in your results.

When I think positional, I think the Catalan.

For the black pieces, prolly the Petroff, and the QGA

The Petroff and the QGA are almost always going to be among the most tactical openings possible below master level.  Wide open centers with really active piece play, and a lot of leeway on when and how to alter the flank pawns.

I'm no expert, but from talking to experts, I got the impression that the Catalan, Reti, and English openings are the most positional ones.  For an approach that mixes these two openings with related (but more tactical) ones like the Queen's Gambit and Slav defenses, see the book "Wojo's Weapons" (warning: Aleksander Wojtkiewicz was a genius, and his approach is riddled with subtle transpositions, so it's difficult for a sub-expert to mimic).

I play a few other places besides this site, I've mostly used e4 here but that's not the case on some other apps and websites I've used to just play around with things. The people I play against here are so much better even at my low rating.

Yes, the English is good for positional play as White.  As Black it would be worth looking at the Benoni and Modern Benoni.  The main reason that this opening beomes positional is because the pawn structure that the position assumes is one that makes it very difficult to determine just exactly when to execute a pawn break.  Because of the complications both White and Black risk being tooo early or too late with a pawn break. 

If you would like to know more please let me know. 

The problem you will run into is that a player may choose to play an unsound opening (e.g. Englund gambit) for the sake of him/her to play a tactical position. So really, a positional game can't be forced from White. If you play  the English (1. c4) and black responds 2...d5, there is going to be some messiness.

You could try the Carwashy System though even here things may get tactical later:

You're not winning or losing games based on the positional nuances of openings. All that choosing a "positional" opening will do is delay the occurrence of tactical blunders a few more moves for either you or your opponent. At this stage of your chess career, you should be looking for opportunities to engage tactically rather than trying to avoid them.

This might work at his level with the opponents he will be facing.  However, this is the Hippo defense.  It saddles the player who chooses this opening with a pronounced space disadvantage that against a player that knows how to exploit it will prove disastrous. 

Sometimes it is better to allow people to learn from the school of hard knocks.  After a while they discover that strategy and tactics are one and the same.  Tactics are the culmination of the corrrect strategy.  Eventually they see that just like all ants are insects, but not all insects are ants.  They discover that all tactics are really strategy.  But not all strategy are tactics.

An ancient Greek Philosopher by the name of Socrates discovered this and came up with a teaching method known as the Socratic method.  He would answer his student's questions with a question.

I don't personally like Hippo systems but know it can be hard getting some tactics going against them.  As white I'd develop classically (two center pawns, knights on c3 and f3, kingside castling, the whole nine yards) and carefully try not overextending, especially a center pawn prematurely.  Though Hedgehogs (c5+b6+d6+e6/c4+b3+d3+e3 perhaps with a6/a3 thrown in) are quite flexible without such a drastic disadvantage.   I like using Hedgehogs in either a Paulsen or Reversed Paulsen, and certain 1...Nf6 2...e6 systems (when I can't go into a mainline Nimzo-Indian such as 1.d4,Nf3 2.c4,e6 3.Nc3,Bb4 4.f3,d5) against 1.d4 or 1.Nf3. 

The Austrian attack w/ bishops on d3 and e3 can lead to immediate tactics against the hippo. It's a handy setup because White can't be move ordered with 1.e4 b6 2.d4 b6 3.Bd3! e.t.c and it can be used against the Modern and similar positions. It's not winning or anything but Black can't just sit there either.  

Anyway I guess you can play the Reti or English and get quiet games. Some people like to play 1.e4 e5 2.Nf3 Nc6 d3 type setups against everything.

Try the Colle as white and the Pirc as black.