Cories spawned again

I've had the same 6 cories for about 6 months and they were in a 55 gallon. But last week I switched out the sand that was in the 55 gallon back to gravel, so I took the cories out and put 2 in each of my 10 gallons that have sand. The next morning, the pair in 1 tank had eggs and they "hatched" on Tuesday. So I looked at the other pairs and found that I had 2 females in one tank, and a male and female in the other. So I moved the corys around so that I had 2 females and a male in 2 tanks. This morning, I have eggs again! My cory fry from Tuesday are 3 days old, they are albino so easy to see against the black sand, but still really tiny. But you can tell they are corys because they swim like them. Somehow 2 other fry made it into my filter even though I have a sponge on the intake, so I think I'll find a media bag and put that over the intake instead. I'll try and get pic's of the little guys today.

I had to take the female that wasn't spawning out because as soon as eggs were left on the glass, she'd come along and eat them. That isn't very nice of her!

Moving the one egg-eating female into the tank with 3 other corys did something because now in that tank someone is laying eggs! Now I just have to watch and see which female is laying the eggs and move the other 2 into the snowball tank. It seems that moving them into a new tank is causing them to breed.