I have a through hull pump going into the bottom of the livewell.

Do I need to plug this after I fill up the livewell?

Also, will it drain back through the pump when I pull the boat out of the water??

Sorry if it's a dumb question

Last question, I have plenty of this tubing around. It's made for bildge and livewells but I usually see everyone here using the clear tubing. Anything wrong with this tubing?

Yes it will drain back through the pump if not plugged. Plug it if you want it to hold water.

Nothing wrong with the tubing mechanically I just don't really like it because the ribs can hold water and debris and you have to buy it in predetermined lengths, its not recommended that you cut it. I prefer the clear braided tubing, its thicker and more ridgid than the clear so it won't collapse or kink as easily.