heres how you tension your chain w/out tensioners--
start by pulling the wheel back so the chain is tight, then tighten both axle nuts. at this point you chain wont be tight enough. loosen you drive side axle nut and push the wheel towards the opposing chainstay, tighten the driveside nut. then loosen the non-drive nut to center the wheel in the frame, and retighten the non-drive nut. you may have to repeat this a couple times to get the chain tensioned where you want it. you dont have to fully tighten the nuts until you have the tension perfect, then tighten you nuts all the way, but dont tighten one side all the way then the other, tight one side a little, then tighten the other side a little, go back and forth till they are kinda tight, then really put you weight on them so prevent slipping.