Random STN?

[alten78]

Hello all, I need to step back for a second and let some other minds look at this and see what I'm missing. I'm getting some random what I'm assuming is STN on different coral, mostly on newer frags.

The current tank has been up and running for a few years now, 2x250w MH (one phoenix one radium, both bulbs less than 4 months old) 2x54 T5's (3mo old bulbs), I only dose potassium nitrate to keep up to 5ppm, kalk (2tsp/gal) in top off for the past 6 months or so.

No real colonies, just frags from the past year or two, almost everything that has been there awhile seems to be ok, maybe a spot or two, but the newer frags seem to be suffering the most. I do dip new pieces in Bayer, after floating in bags to match temp...

Current parameters

Alk (hanna)- 8.8dkh
Calc (API) - 440
Mg (Nyos) 1260
Po4 (hanna 713) 0 - Only algae is the fine dust that immediately goes back
NO3 (Salifert) 5ppm
SG 1.025

Some time back I really realized I was running things too clean, which may be the case here? Things certainly got better and more colorful. I think I feed heavier daily (cube mysis, oyster feast, rods food, formula 2 flakes, new spectrum pellets) to fairly stocked 75g (2 clowns, 2 bangaii cardinals, 6line, foxface, tomini tang, 2 lyretails, orchid dottyback). I took the carbon offline, run the nwb150 2/3 of the time.

Ive had this for awhile, starting to finally color up but theres a few white spots towards the bottom
<a href="http://s4.photobucket.com/user/alten78/media/DSC_0057_zpsglc3jue0.jpg.html" target="_blank"><img src="http://i4.photobucket.com/albums/y139/alten78/DSC_0057_zpsglc3jue0.jpg" border="0" alt=" photo DSC_0057_zpsglc3jue0.jpg"/></a>

Newer frags (previously under 400w MH), you can see the dead spots on the milli, that's a red planet behind it, and a random frag to the right


Red dragon has new growth, but its hard to tell that there is a few spots on the right as well


A few pics of other pieces that appear to be unaffected

 

[Galaxyreef]

Having the same issue right now with STN. Seems to have come out of nowhere. All parameters have been in acceptable ranges and stable. Have yet to find the root cause. I upped my water changes to weekly vs bi weekly and may run a little carbon and see how things respond. I know swings in alk are a common culprit for STN at the bases.

 

[alten78]

It can be frustrating when things go well for an extended period of time and then suddenly change, especially as some thrive and others die.

Everything I have started as a small frag, had a green milli that finally started getting big when it took a turn for the worse and eventually died, meanwhile everything else did well. Two of the 6 frags I put in the tank recently are millis that aren't doing well while others are ok. I had to ship my apex to Neptune a few times over the past couple months so maybe something isn't as stable as I think it is (still waiting for it to return, I am not impressed by their troubleshooting fwiw, although, I am very critical of it because I troubleshoot in IT all day long.)

For myself, I took off the carbon and cut back on water changes to try to dirty up the tank some and see if lack of nutrients is my issue.