I can not suggest a vendor for Matala equipment because I use Vertex diffusers I bought from Hoosier Pond Pros, but Matala is listed on the PB resource page...
https://www.pondboss.com/Resources?lid=271&lci=1Keep in mind that any time you put 2 diffusers on a single line, one of them will probably suffer from lack of air flow especially if they are in series and/or at different depths...the last one in the line and/or the deeper one will be weaker.
I use flow control valves on each line leaving my pump manifold and only have one diffuser for each line. This allows me to adjust the flow to each one and balance (or imbalance) the flows.
This is ideal, but not entirely necessary. Should you chose to put 2 difussers on 1 line...run the 1 line from the pump out to a "T" (connected to the bottom of the "T") and then run 2 lines from the tops of the "T" out to the diffusers. Keeping the diffuser lines similar in length and keeping the diffusers in the same depth of water should allow them both to flow at very similar rates. I, personally, would want to put the "T" at the pump. This helps maintaining the system when it comes time to move the diffusers around or trouble shooting, but comes at a cost for more line.
