I am not sure how to solve your problem, but I use a manual mini vac on my 10g and 20g, I control the flow by putting my finger at the end so I don't suck up the gravel and can stop the flow. Then I pull it from the gravel and suck the debris through. Tip if sucking the tube to get it started. Hold end of tube above water line. When it gets close, keeping your finger close to the end, slowly lower hose (while keeping the head in the tank water), once the water reaches your finger you can cover end with finger and control what you clean. Avoiding the clogging.