Goldfish will turn right around and eat the eggs they just laid so keep them well fed and provide some very dense place for them to lay their eggs. I have a tank right in front of the window that has eloda growing thickly all through the tank. When I see two goldfish getting amorous I move them to this tank to spawn and when there done I move them back. You don't have the option of moving your fish so I would put some thick spawning material (or plants) in the center and after you know they have spawned place a barrier around the area. You will need to provide places for your fry to hide while growing up otherwise they will become food for their parents. Spawning will happen when the temperature of the water reaches 72 degrees consistently for several days in a row. What part of California do you live in? I'm in Cloverdale, about 4 hours north of San Francisco. Here in our micro climate we can grow citrus. Hence the Citrus Fair and Citrus Fair Drive (my off-ramp name). You might also want to try kokosgoldfish.com. They have some very smart people there and the are goldfish only. I wish you the best of luck,
Glenn