I have a seahorse tank for the past two years. I do not have any mechanical filtration on it such as skimmer, hob filter, nothing. All I have is 20 lbs of live sand, 20 lbs of live rocks, and a CPR HOB refugium with DSB and Macroalgae. My readings are 0 ammonia, 0 nitrite, and 0 nitrate. On top of that, my DT is always full of Pods. I used to once a month, I would just blow the detritus from the sand bed with a small powerhead and then I put on a cheap hob filter from walmart for 12-24 hours to remove all the detritus then remove it. Now, I have no sign of detritus at all on the sand bed since my tank is now mature with bristle worms and nassarius nail doing the cleaning. All I do now is to do a water change once every two weeks. Have my seahorses for two years and still going strong.