I use regular hob filters that i make my own filter media for. I use regular blue media sheets that i cut to fit folded over into a roll, inside the roll i have stuff like carbon placed in a ladies knee hi panty hose with the top tied into a knot, then i take some filter floss (not too thick) and put it around the carbon and roll it up into the blue filter media sheet i made. I then stuff that down into the empty cartridge compartments. I stuff it so the open top and bottoom ends are on the sides of the cartridge space. Check it often after you make it the first couple times to make sure you have the right balance of media in the filter, too much or too dense and it could overflow (also make sure the hob is tilted slightly forward into the tank (rip up a old paper back novel if you need to and jam it inbetween the filter and the back glass. If your back glass is not painted you can tape a piece of black posterboard to the cover of book piece and it will match a black hob filter). I use the cheap HOB filters from walmart LOL.With the money i save i am able to over filter every tank i have, I put extra hobs on each tank, if one filter is rated for 75 gallons and my tank is 75 gallons then i put two of the hobs on it with a skimmer. I never have any trouble and my tanks are crystal clear. your canister filter might just have trapped air in it. Take it down, clean it out good and restart it. If it still makes the micro bubbles then try shutting the power off, close the valves, then open the inflow valve then the outflow valve (you will hear the water move into the filter. Then plug it in and start kind of shaking or tilting back and forth the top of the filter to help trapped water escape. I bought a new drilled tank last week that i hooked my canister to and had micro bubbles and intermittent low flow out of it. What i described for you to do is how i fixed it. I had to repeat the on /off and tilting /jarring the canister several times before it cleared. Took about 30 min of swearing and non stop work but all is good now. Good luck.