They've always been low because I've rarely had many fish in the system...sometimes no fish at all. But after so many years, including the last 3-4 with some neglect, a bit of PO4 had accumulated...nothing tremendous (maybe 0.8? I kinda forget.) but still enough to make the situation ripe. In a nutshell, NO3 was persistently low and I ended up with an outbreak of #chrysophytes.
I can't remember the exact date where the polyp blew out (I need to go back through photos) but looking back at my testing diary, the peak readings I had were:
0.63 ppm PO4 along with 2 ppm NO3
Then three weeks later of 10 mL of KNO3 + 5 drips of amino acid per day...
0.05 ppm PO4 along with 25 ppm NO3
I did find the post where that happened in my system thread: post
#59
I'm not sure if I posted a pic of this Favia though...I have one from September on there where he was still fine. And that post I just linked is from October. So it'll be interesting if I can dig up the date on the photos with the "emploded polyp".
That's what I was saying about the zoox....they went past brown to nearly-black though!
I failed to mention that this polyp was also the least-lit on the colony (facing away from the lights), and the flow back there probably isn't what it was either.
