I did it! Finally replaced all gravel in my 125 g tank

[fish lover]

Thanks guys for the great advise. I did it in three days using the 2"
tube with my 40% water change. Hope everything is going to be OK. So
far the discus look happy. I know I may have cloudy water for few
days. I will watch the ammo level. The PH level dropped from 7.7 to
7.45, which is kind of bit too much for a day. I will have to watch it
for the next few days. I think the peat is going to kick in and lower
the PH in the next few days even more. Just hope it is not too much
too fast. I may have to use PH up for a day or two to slow down the
decrease. I hate to do that.

Thanks guys/gals again.