Why are ammonium ions reabsorbed in the thick ascending limb during acid secretion?
Isn't it all to do with the reabsorption of water, i.e. everything gets flushed out in the Bowman's capsule and then some stuff is reabsorbed to lower the water potential of blood, so water is reabsorbed as well.

I guess I figured it was easier to have a leakier sieve at the Bowman's capsule than try to only release the waste products via facilitated diffusion.