Are those real reef rocks with fake corraline or real corraline? Tank looks pretty new and sterile. I started SPS in my tank after 7 days and those I first put in are still alive and kicking and are biggest ones I have now 9 months later. I don't change water on my tank and I dose CA, ALK, MG, and Fauna Marin color elements . I used to have GFO and Carbon and change water all the time and had no success with sps, they floundered along and were pale and eventually would stn never growing a MM. Now, every 45 days I take a reference pic and these things are growing significantly with minimal maintenance work required. Best of both worlds, try dosing Fauna Marin color elements and take off any carbon or gfo if you are running any. Let me know if that works, I bet it does.
They're actually not turning brown first, they receded from the base and had normal coloring most of the time.
I've seen tanks stayed for week with sps that are doing well, but maybe there is something going on with the sheer of the tank i guess.
The green one center right is either a sunset Monti or psammacora. I have a few chalices doing well on the other side of the tank but you can't see them from the picture.
The center right sps is unfortunate totally dead now, it was a copps cali cali.
Center bottom left is struggling im pretty sure because it's infested with aptasia in the skeleton underneath.
Nothing is getting direct flow, my power heads are pointed at the glass and bouncing around the tank from there.
I've heard similar stories about Po4, that's why I'm hesitant to call that the issue, i am trying to lower it with phosguard though.
Haven't tested my rodi, i will.
Both monti's polyps are still out, rainbow Monti with red polyps and sunset Monti with green ones.
Ive been doing water changes monthly, my nitrates never read more than 5 though. I am thinking about starting to do them more.
I'll split up the dosing more and see if that helps any, they've been set to add at 15 minutes apart. Thanks!
Based on your picture, your skimmer is pulling a lot of stuff out of the water. If you skim aggressively enough you can have no algae even with Phosphate and Nitrate in the water. I would back the skimmer off to dry skim(gunk mostly collects in the neck) and lower the level of light by at least a third.
If you are concerned with something leaching from the sand, a polyfilter in the sump is good insurance and its a cheap way to give you peace of mind.
Your tank is not too young. You can grow SPS in a 3 week old tank. The age bit is outdated urban lore. Your tank will support more SPS in time but there's no reason it shouldn't now.
Your black sand has the same buffering ability as white sand, which you're not relying on anyway.
It sounds like you have sufficient light and flow.
Your phosphate level isn't a problem though it can't hurt to lower it with water changes. Phosguard is an aluminum based product that's outdated and no the best solution. It potentially can introduce problems.
Only changing water once a month and not feeding or supplementing any coral foods means the only food sources for the SPS are light and detritus from the fish.
I'd change a significant amount of water and start doing water changes at least every 2 weeks. You also don't mention any dosing of aminos or feeding the corals. Monthly water changes are not sufficient for many SPS.
I only see 1 clown fish and I see what looks like cyano on the sand.
How many fish are in the tank ?
Have you siphoned/cleaned the sand since you set the tank up ? The sand be looks pretty deep and if that's cyano it may be holding too much detritus and that's where your nitrates are coming from.
I've been keeping SPS for 25+ years, been in the hobby for 40+ years. I have a pretty good idea of how to run a reef tank :dance:
Are those real reef rocks with fake corraline or real corraline? Tank looks pretty new and sterile. I started SPS in my tank after 7 days and those I first put in are still alive and kicking and are biggest ones I have now 9 months later. I don't change water on my tank and I dose CA, ALK, MG, and Fauna Marin color elements . I used to have GFO and Carbon and change water all the time and had no success with sps, they floundered along and were pale and eventually would stn never growing a MM. Now, every 45 days I take a reference pic and these things are growing significantly with minimal maintenance work required. Best of both worlds, try dosing Fauna Marin color elements and take off any carbon or gfo if you are running any. Let me know if that works, I bet it does.
When you say receded from the base, are you saying they thin slowly there then die off a little at a time, or are you seeing the pieces of flesh slough off the skeleton from the base up? If it s the first It's similar to what Ive seen in my tank. The cause seemed to be a combination of too much light and too aggressive skimming. Based on your picture, your skimmer is pulling a lot of stuff out of the water. If you skim aggressively enough you can have no algae even with Phosphate and Nitrate in the water. I would back the skimmer off to dry skim(gunk mostly collects in the neck) and lower the level of light by at least a third.
If you are concerned with something leaching from the sand, a polyfilter in the sump is good insurance and its a cheap way to give you peace of mind.
What do you calibrate your refractometer with? I had this same issue with my sps until i realized my tank was sitting at 1.022 because i was using ro water instead of a calibration solution. i picked up a bottle of 35ppt solution, corrected the issue, i haven't had a problem since. Might not be your problem, but just a suggestion.
I'd say do weekly wc simply because that's standard for a tank that size. Then I'd say just because, you should get that gfo rollin and get that p04 down. But before all that I would calibrate my refractor and make sure it's right...
What salt brand are you using?