So I just started trying to keep sps in my tank. I started by getting my parameters where i wanted and maintained them stable by dosing using seachem fusion. My cal is 440 alk is 8.6 and mag is 1440. Nitrates is 5 and po4 is reading as zero. When i bought these sps frags they where fully colored but now im noticing white tips on only a few branches and not all of the sps have them. Is this normal?