Provided your plumbing is correct and you’re not pumping in more than what you’re withdrawing then you’ll be fine.
Why only 12 gal again?
You can put a 27 gal black and yellow HD tote in there and whatever you want on the outside and make it work. Just that easy.
All you need is
One 10ft x 1 1/2” pvc,
Two 1/12” bulkhead unuions
1-2 1 1/2” elbows pending how you connect it.
1 1/2” ball valve or two
3/4” black tubing
3/4” bulkhead union
3/4” hose clamps
1-2 3/4” elbows
1-2 3/4” cutoff valves.
950 gph air pump w/ 6 way splitter.
Six 2”x2” air stones
1/4” black tubing
400 gph water pump
Pvc glue
Pvc cutters or saw and put it together.
Easy peasy! 
