My homemade system utilizes a magnetic stir bar and magnetic stir plate of my own design, and its constant current engine is an LM334Z. My electrodes have been set at about 1" apart. Perhaps I need to increase the distance between them? It does seem that at 1,000 uA of constant current it is taking far too long. I'm beginning to think that I need 1,000 uA per square inch of electrodes overall.
Did you actually measure yours at 1,000 uA (1 mA), or are you only assuming it to be at that value?