need some advice

I've had my reef tank up and running for 2 years now 4ft long dont know litreage no skimmer plenty of flow live rock and a canister filter with rubble and gfo not had that many issues and canister is cleaned monthly tank parameters are good all ok on that front I know it's debate able about canisters but my setup works and is near silent which is a bonus as it's in my bedroom lol now I've added a hob refugium appx 15 litres and am planning on splitting my canister outflow pipe into 2. 1 direct out in dp other used to power refugium plus will run a ball valve to adjust flow to refugium. Has anyone done this before tips would be grateful???

 

Forgot to mention no sump led lighting pair of clowns dragonnet goby bicolour blenny hermits zombie snails other snails lots of brittle stars etc