2 things we noticed when watching the USA SSC raid stream

1. Hydross aggro range

Hydross aggro range should be huge. If you would normally pull by walking up to him, you would pull him so early that he would switch to poison form when you got to him. People even used invis pots so that they would cancel the invis and start the fight where he stands.

http://wowwiki.wikia.com/wiki/Hydross_the_Unstable#Starting_the_Fight

https://youtu.be/sqjCkoQxxLU?t=8
In this video you can see that the tank is already in aggro range and that the moment he becomes LoS of Hydross, he runs towards the tank.
http://i.imgur.com/S8qpZnp.jpg

2. Lurker's Geyser ability.

We noticed that during the whole fight, we did not see him use his geyser ability. He should use it on a random person that is not a tank dealing 3-4k frost damage that is resistible and deal a 10 yard knockback to the person and people within 3 or 5 around him.

http://www.worldofstrats.com/LurkerBelow/tabid/56/Default.aspx
http://www.tentonhammer.com/guides/serpentshrine-cavern-guide-the-lurker-below
http://wowwiki.wikia.com/wiki/The_Lurker_Below?oldid=1617527