check the irrigation section at HD or Lowe's. but consider that you'll lose less flow using a straight outlet fitting, despite increased head. canisters are closed loops, so vertical head has less of an effect on flow. friction from tubing and 90 degree bends decrease flow more than vertical head height.
just took a look at the elbow you're talking about. nice bend in that fitting, curved not, straight 90 degree. you'd have a same situation if you use a straight output because the tubing will have a curved 90 degree bend to get back up to the tank.