keep the small one behind the rocks. If you plan on sticking with the 2 MJs place them in the back and angle them both towards the front center. For better flow I would replace the MJ's with koralias or tunze nanos for a wider more random flow. Also if your zoas are constantly reaching upwards and over stretching, that is an indication they are not reciving enough light. If they are open and not as outstrecthed that is a good sign.

HTH