I want to back my baitcaster with some Mono before I put on 12# fluorocarbon. Should the mono be 12# too or can it be 8 or 10# Does it matter what pound test the backing is? 

I don't think it matters. I've used 8-15# mono backing for both 12 & 15# fluoro. I just use whatever mono I can buy super cheap at Wally World. 

depends, if you are around some big fish and think they might pull you to your backing, your backing should be same or higher lb just so you dont break off if you set the drag too high

For me I look at diameter instead of lbs. I match diameter with diameter.

If the lbs match up then even better.

for bass it doesn't matter alot, but the line to backing knots are stronger and easier to tie if the diameters are close to the same. if you have some 8# and some 10#, i'd use the 10, but i wouldn't go out and buy a new spool of 12 just to be exact.

Use what ever you got on hand for backing or buy something cheap. Really doesn't matter for bass fishing.

Whatever is cheap and close to the same size. Ideally that knot will never see the water so I don't think it matters what kind of knot or line you use. I usually do a one-sided overhand bend knot because it's simple and has a small profile.

Do you guys usually do like 1/2 and 1/2 for the backing?  Fill up half the spool with mono and half flouro?

Cover the knot with a piece of tape to keep the knot from messing with your cast.  This is critical with a spinning reel.

i'm probably putting a bit more than half mono, more like 2/3rds mono 1/3rd floro. i use a double improved cinch knot to connect - three wraps on each side. i do the same with braid, but more braid and not as much backing.

Match by Diameter

24 minutes ago, npl_texas said:

Do you guys usually do like 1/2 and 1/2 for the backing?  Fill up half the spool with mono and half flouro?

Depends what I plan to use the reel for. If I want to make long casts then usually half and half, if it's for something like pitching jigs then 2/3 backing is probably fine. 

13 hours ago, bigturtle said:

depends, if you are around some big fish and think they might pull you to your backing, your backing should be same or higher lb just so you dont break off if you set the drag too high

 

 

You'd be hard pressed to find any freshwater fish (outside of maybe a large catfish, carp, or striper) that would be able to spool you down to your backing knot. 

3 minutes ago, fishballer06 said:

 

 

You'd be hard pressed to find any freshwater fish (outside of maybe a large catfish, carp, or striper) that would be able to spool you down to your backing knot. 

 

Lake Ontario: northern pike, musky, king/coho/Atlantic salmon, brown trout, steelhead, carp, sturgeon, and a couple others can all make drag stripping runs on 12# bass tackle.  And yes, there are times of the year where these alternate species' location intersects with bass.

25 minutes ago, fishballer06 said:

 

 

You'd be hard pressed to find any freshwater fish (outside of maybe a large catfish, carp, or striper) that would be able to spool you down to your backing knot. 

Depends where you are and how deep your spool is, it can easily be done

I guess it also depends how far into your cast you are when you hook the fish.  I've never had a problem running 60-70yds of line for bass fishing only.    

I have been using some cheap 10 pound H2O express line for backing for every reel i own for over 5 years now.  Bought a bunch of it for .50 cent a roll and i dont like it.  so its backing until these next 4 rolls are gone.  FYI i never fish line over 17 pound.  Mostly 12 pound mono or co polymer line on everything