Gel Problem

I tried to do an SDS-PAGE gel but after pouring the separation gel, this is what I got:




When I poured the gel, I made sure that there were no air bubbles whatsoever and the top was a very smooth line. No air bubbles developed during polymerization either but for some reason it polymerized irregularly! What I've noticed is that 2-3 mm at the very top, there was a liquid layer, up to the bottom marker line (the image was taken after I poured out the liquid that remained to make the gel surface more visible for the pic). I'm sure I left it to stand enough because I left it for like 30 mins.

I tried doing another gel and adding water on top of it...I did get a smooth surface but the front was obtained very low down the plate as if the water I added diluted the first few millimeters of the gel and so the first 1 cm from the top didn't polymerize.

Any ideas? I've tried 2 recipes and got the same results when it comes to surface 'smoothness'.