Or... Just add a bag of Matrix to your sump. That's what it's made for. (Either a DSB or Matrix will require a few months to work...)All of the aforementioned advice above is great. My input on this is different and may or may not be applicable in your situation. There was a great PowerPoint on nitrates at aquashella recently by Sanjay and he mentioned an excellent example of exporting nitrates. We have our filters and our tech and aerobic bacteria does excellent but there's also anaerobic bacteria that could help. Essentially you'll need a very deep sand bed of at least 8 to 10 inches minimum and then alot more nitrates are removed by the anaerobic bacteria in the deep anoxic region of the sand bed. If a deep sand bed isn't possible then you can set up a separate system tied into your sump or a canister filter. Anything that'll hold the height you need to create a deep bed. Flow water through it and you'll have great results . Hope this helps I'm still a noob as well. But don't be scared to ask questions all the great r2r family have taught me so much in such a short time. Keep up the work and hope you find a solution