I have refurbished some of my ponds and to have a flow-through setup (one pond to the other and then through the filter and back to the first pond), they are on average about 3ft deep..... will Corries breed at this depth?
yes, they should still breed, no matter how deep the water is.
my cory breeding tank is full to the top and they breed alot (but you gotta be quick to get the eggs as they will get eaten)