I have had similar problems on my tank. As you can see by my user I usually build/construct everything I possibly can, like stands, lighting and once an entire tank. But, a surface skimmer for a canister filter is something I would never trying to construct. Its not worth the expense of time and money.
I had an Eheim Ecco and I purcahsed a Eheim SSE from an LFS for like $30!!! I hated it, It was very tweaky and not worth the $ - Eheim.
Then I was at a warehouse type store and came across the Aquaclear surface skimmer for like $13.00. It is intended to attach to the input of an AQ HOB. But, with a little adapter I had lying around, I got it connected to the odd sized Eheim tubing. It worked like a dream. It is almost infinitely adjustable and has input on the bottom of the tube, so it can always be pulling the right amount of water into the skimmer with out making noise. I now have one on three tanks. ONe is hooked up to a mag 350 and no problem with noise and it easily handles the flow. I think there is Fluval version that may fit canister filter tubing better. Best of all it is $7.99 at Bigals!!!
BTW - I sold that Ecco to an "Eheim guy" for $40, then bought Rena Filstar XP1 for $45 on sale and I am much happier with it.