Congratulations. Seems to be going well.
I'm going on observations more so than experience but I would suggest the following.
1. For the size of plants it looks like you are growing, a 250w HPS may not be enough.
2. The pots seem large for the available lighting.
3. You should probably build a wooden frame/box around the setup and coat the whole thing with mylar. Seems to be a fair bit of light loss going on.
4. Move the electrical equipment and wiring up off the floor. Even if its only 10cms.