C-man is right on with the water changes. It is better to do more frequent, smaller water changes then larger less frequent changes.
But your tank is really overstocked. It will probably work out fine for a while, but once the rams start to mature, my guess is that you'll end up with one male at best, and maybe a female or two. There just isn't a lot of room in a 29 for all to get a good teritory.
Heven forbid if you get two pairs actualy breeding at the same time. I would say they would darn near kill everything else in the tank if this were to happen.
If you can keep a close eye on them as they mature and either pull out the extra's before they get killed, or remove the pair then you'll be better off. Or just give them a much larger tank.