I just can't seem to get ahold of my nitrates in my 35 gallon tank. All other parameters are perfect. I do a 5-10 gallon water change weekly and I am running an aquac remora Skimmer, half gallon refugium with chaeto algae, and a penguin 200 with carbon inserts. I have 2 fish (mccoskers flasher wrasse & ocellaris clown), a few of different types of snails (nerite, trochus, matgarite, & nassaris) and 2 shrimp (peppermint & cleaner). I wouldn't think the bioload would be too much on my tank. I have plenty of live rock and about 3 inch bed of sand. I also have corals including many zoas, mushrooms, polyps, and a Duncan. I just did a WC and my nitrates are at 18 ppm! Other params are calcium- 410ppm. KH- 161.1ppm. Phosphate- 0.10ppm (which is another thing I don't like). Salinity- 1.245. Temp- 79°f. Any ideas why my nirtrates wont go down and stay down and also the phosphates?