I am not sure what corals you have but nitrates measuring 0 is not healthy for any of them depending on what you are stocking SPS, LPS, ect that will ultimately determine what level you need. Its really a trial and error but 0 is not good, try for something near 3- 5 and see if your coral improves and similarly for phosphates, you need a little in the system like 0.02-0.03. If you starve it completely they will waste away. Sometime even sever algae growth can affect coral growth as they can strip nutrients fast. But your water chemistry looks good.
I have a toadstool leather, and a couple of small frags: candy cane, zoa, favia, plating montipora and pocillopora.
Toadstool and montipora seem happy and are growing well, candy cane appears healthy enough, but not really growing, favia looks like it's bleaching slightly at the moment, and the pocillopora appears to have pretty much died overnight
what is your lighting like? what are you using and what is your lighting duration. When i had a serious algae problem I cut back my light and then also moved the spectrum more towards the blues and it helped quite some what in slowing down its growth, the corals did sulk a little and I even lost one or two but it helped with the rapid growth.
I'm using 2x Kessil A160we, 09:00 - 19:00 period peaking at 60% intensity at midday
I'll try lowering the white level and drop the intensity, see if that makes a difference
where did you get your live rock and sand from? were they second had or used before? how long did you cycle your tank before adding live stock. I usually recommend to everyone cycling a new tank with live rock to use a protein skimmer and regular phosphate remover and testing. If phosphate is not properly dealt with it will attack to rocks only to leech out later, even though test kit will show good phosphate level the algae get to it quick, specially if you have lots.
Live rock was a mix - most of it was dead & dried from someone who had broken down their tank - scrubbed, and then soaked in RODI for a couple of days before sticking in the tank. Also a couple of bits from the LFS to seed the rest of it. Sand was dry aragonite, can't remember the brand, but from the LFS, thoroughly rinsed, first in tap water then last rinse with RODI.
I would also test your DI water for nitrates and phosphates and see what they are, those hand held TDS meters are not always accurate. Sometimes changing salt can cause system imbalance and outbreaks of things like cyano and it could be a potential cause.
Tested it, both plain RODI and freshly mixed salt, and both are 0 on nitrates and phosphates. I'm using the same brand salt as my LFS were using, so unless I have a bad batch I don't think it's that - only difference is I have increased the salinity slightly - theirs was at 1.023sg
Also this is a new tank by marine standards and algae and cyano outbreaks are almost given and they will burn themselves out eventually in most cases and I had a similar phase when starting out, with both cyano and hairs algae and from time to time get outbreaks that burn out. So don't give up just be patient and keep water parameters good and try not to dose your display tank too much with miracle cures. Give it few months and see how it goes and if it does not work then you can try other things more drastic.
I guess at the moment I'm more concerned about it smothering my corals than appearance - I'm realise it's not going to be a quick fix, but feels like a losing battle constantly trying to keep the frags clear!!
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