Welcome SpeedGP! Your'e off to a good start. What you have built is referred to as a wet cell. (A cell that has the electrode plates submerged in a tank). I started with a similar cell and soon discovered that it is one of the most inefficient electrolysis devices out there. It will boil within a 1/2 hour. The goop on the plate edges wont do much to stop current leakage and over heating either. Also, your plate gaps need to be evenly spaced. Between 1/16 and 1/4 inch apart. The reaction will be concentrated at the corners that are closest to each other. But, the closer they are, the more important flatness becomes. And, the plates may warp with heat and short out. (Yes, it matters if your bi-polar plates touch). Plate proximity also depends on the concentration of electrolyte you are using.
I couldn't really tell how the plates are connected. If you are using a 12 volt battery charger, it should be something like this: (BP stands for the unconnected Bi-Polar plates).
+/BP/BP/BP/BP/-/BP/BP/BP/BP/+/BP/BP/BP/BP/-. This will keep the plate gap (the /) voltage to around 2.4v and will minimize heating.
Use the search function on this site to learn about dry cells. (A cell that only has fluid between the electrodes. The electrode edges are dry). You will discover that gas production is much more for the same power you are using now. Good luck!