I use 1 Clear Big Blue { Dimensions: 23-3/8" x 7-1/4" (594 mm x 184 mm) } Whole House filter with BIO balls and 1in intake/out put , with the Eheim 2262 I get 100% dissolve co2 . Have a pvc in the center go all the way down the bottom then the water will run up thru the bio balls and out .
I have the co2 inter thru intake before it inters the reactor guess I can add a shut off ball valve and slow down the out put just a bit.