Not being critical just advising, but your engine drive chain is very loose. You want 1/2" to 3/4" of slack. More or less can cause you problems.
Have you tried running without the chain tensioner? It appears you would have no frame clearance issues that would require the tensioner. Your pedal chain tension is already taken care of by he derailer. You'll need to shorten the chain but running without the tensioner is a better option.
Tom