How do you seed coralline algae? I have a 24g nano cube with a ton of coralline algae in it but I have a 12g that barely has any. I was wondering if its possible to see my 12g with the coralline from the 24g?

take one of the rocks with coraline on it and scrape it into the other tank.

Scrape some of the coralline off the back wall in the 24g and put it into the water column of the 12g. If the water parameters are in favor of coralline growth, you'll see it!

try and do seed the tank right after your water change.. that way you don't suck out what you just seeded.

Right now I have a hair algae problem so I was thinking maybe I should wait until after I get rid of the hair algae to seed it?

Hair algae wouldn't affect the seeding of coraline one way or the other, but it owuld probably be best to address the issue before doing to much else.

coraline loves plastic, put some pvc inside the tank that has an abundance of it...let it go...scrape the coraline off in the tank you want to seed. simple as that