Bog filter advice

This is my first year utilizing a bog filter for a 250 gallon pond. I put 3-4 bags of lava rock and pebbles in the bog but last night my pond completely drained. I started filling it with water but I noticed water kept spilling out the overflow. Im under the impression I got a clog in the bog but I dont want to disrupt the plants or the set up I got going on. Is there a solution to unclogging it besides tearing everything apart?