ASAP, do a large water change with dechlorinator to get ammonia levels down. the filter will work, as long as the turnover is adequate. Someone who knows about that particular filter can probably say more about how to add more biological filtration if you want it, but in the meantime, please do a large water change to get ammonia levels down. The problem may not be the filter itself, but the fact that you are still cycling and need to do frequent water changes until your cycle is complete.
joy to the fishes in the deep blue sea
55, 30, 30, 20, 10, and 10-gal. freshwater tropical tanks