Sounds like an interesting set up!

I'm now completely spoilt, having worked at public aquaria and having 2 meter and 1.5 meter tanks at home, I now regard any tank I can lift on my own as small

Breeding fish is all about letting them as opposed to making them (hope that makes sense!) and conditions in your nice biotope tank are obviously conducive to spawning.

Normally a male's territory and spawning site is governed by ongoing disputes with the neighbours. He'll probably use the same nest again but if they respawn I'd expect him to drive the older fry away (in a tank he'll probably eat them as they've nowhere to escape to). I'd suggest placing a mirror on the far side pane of the tank to give him another male to interact with which will make life easier for the females too.

As you can see, two tanks is the best way to rear these fish, with a rearing tank used for the first batch of fry to make room for the next. That's kind of how I ended up with over thirty-five tanks a few years ago..