need help with my sump

i have a 75g tank that i just took all my bio-balls out and put liverock in but i just dont know how much to put in. my sump is 30&half long 10&half wide 13&half high the box that is inside is 20 in the sump but out of the sump its15&half tall thanks

 

I'm having a hard time understanding Sorry, your 75G tank had bio-balls in it or in a filter area?
I assume you sump measurements are in inches so that would be about a 20G tank.(18.68)

OK so I think you want to know how much LR is needed in your sump? Do you have LR in your tank? if so you don't half to have LR in your sump but it can't hurt. The More LR the better.
if you have a picture of you set up or a link to the sump manufacture that would help

J

 

i also have a 75g with a wet/dry that has live rock. i put the live rock upto the water line, then bioballs on top of that to quiet it down. there is better media out there other than live rock that has more surface area to rid NO3. my live rock is there for the internal organisms that benefit the enviroment. in order to do that they need to stay under water. you can either just use the live rock upto the water line, or place a media on top of that to quiet the noise, choice is up to you. my suggestion is to keep the live rock under water.

 

Yes, as much as you can fit under the waterline of the sump.

 

if your into l/r filtration then you can never have enought filler up buddy to the waterline