Breeding tank set ups

Just interested in what people use as breeding tanks set ups.
I've got 2x 2ft tanks bare with sponge filter and 2.5ft tank with under gravel. I find that the bare tanks Ph have been fluctuating so recently changed the 2.5ft tank to under gravel to see if this keeps it more stable.
I was thinking about painting the back and sides of the tanks, just to stop the pairs seeing each other and other reflections spooking them. Any experiences of what colour works the best or avoid?
The tank decor consists of a large plastic amazon sword and spawning cone to provide a suitable suit and a bit of privacy.

I use air driven foam filters with fine quartz gravel on the base, plants & spawning cones (aka flower pots) in my breeding tanks.
for more information about my set up see this thread ....
http://www.uk-angelfishforum.org.uk/t384-robs-fish-room-tales

For more information about several fishrooms try this link...
http://www.uk-angelfishforum.org.uk/f21-tales-from-our-fish-rooms