Trouble in Paradise - SPS Bleaching

Charlie the Reefer · May 29, 2024

Hey everyone. I have 65 some different acropora frags/mini/colonies in my collection at this point. Everything has been going great for the last few months. Not one coral death, awesome growth on most pieces. Keeping everything from torts, montis, granulosa, speciosa, tenuis, etc. Normally my polyp extension on basically everything is great, with the filamental tentacles or w/e popped out too.

The other day I checked the tank at approx 3PM for the first time in the day (Tuesday). Everything looked significantly bleached. Polyp extension was VERY bad, worst I have ever seen it. Things just looked like they were dying (note nothing has actually died yet). Sorry don't have pics yet.

So... I looked at apex. The night before/Tuesday morning, at 1AM, I observed the below ORP drop. Super crazy! You can see for the last whole week prior ORP fluctuated within 320-340. Then dropped ~100 over the course of the next 24 hours. Note ORP was approx 300 at 3PM when I observed the bleached SPS.

Now... It was pretty clear to me something that could be wrong are nutrients. I tested nitrate/phosphate with Hanna immediately. Nitrate was bottomed out, 0. Phosphate tested at .04. I dosed some nitrate just to ensure it's not bottomed out ( I have done this before with no ill effects).

Also, I have been ramping up my lighting over the last two months. I have 2 AI blade glows with 4x radion XR15s over a 60" x 24" 20.5" tank. I have slowly been ramping to near 100%, things are at approx 80% at this point. Note I did not change lighting for at least the last week and a half, so if it has to do with the lighting ramp (definitely could) it's what I changed a week ago. So, I significantly turned down my lighting thinking I'm just burning the crap out of the corals.

I made those changes/tests at approx 6PM yesterday. Then, this morning at 7AM, I re-tested nitrate/phosphate. Nitrate 4.0, phosphate .13. I dosed a tad more nitrate. Since 6PM also, as you can see by chart, ORP has begun to climb back up to usual levels.

Weirdly enough, alk consumption up until this afternoon today has been very steady. I've tested alk every 3 hours or so. Alk JUST stopped getting consumed meaningfully a couple hours ago, and I've had to tone down my kalk dosage. I'm sure turning the lights down a ton had something to do with this. Alk consistently tests ~8.0. My alk has never fluctuated more than .3 in the same day, since I got SPS.

So... IDK why really I'm posting this. I hope things come back. I'm wondering has anyone ever seen this before? Basically all corals bleaching white at the same time! I think it's pretty clear what happened, although I can def be wrong and maybe I'm just presenting this narrative fallacy. The BIGGEST puzzle to me is why there was a sudden, rapid ORP drop at 1AM! Lights are out at 9PM. I have a fuge with chaeto with reverse night cycle in addition to frag tank with reverse night cycle. Nothing died yet though (at least to my knowledge). Definitely all fish are accounted for. It's just very interesting/puzzling. What caused the ORP drop and why....?

Would really appreciate any thoughts on the matter. Also open to criticism for how I reacted to this scenario or any random thoughts. I'll keep yall posted.

Formulator · May 30, 2024

Looks like something died or a deep sand bed was disturbed. Any chance of either of those things?

Charlie the Reefer · May 30, 2024

Formulator said:
Looks like something died or a deep sand bed was disturbed. Any chance of either of those things?

I don’t know what could have died, at least anything substantial in size. All fish accounted for (but could have been large snail or something.)

I do have a fairly deep sand bed but it has never been disturbed by me. I do have two yellow corris wrasse, nassarius snails, and a diamond back goby that regularly sift/sleep in the sand.

Thanks for your response/ideas. My ORP has returned to its normal level after testing nitrate/phosphate every 9 hours or so and keeping them detectable. I’m still very puzzzled at the orp drop!

ryanjohn1 · May 30, 2024

Strange occurrence. Bleaching could have come from bottomed out nutrients and high light levels. Corals weee hungry and ate all available or skimmer pulled everything. Do you feed the fish heavy or at least multiple times a day.

ryanjohn1 · May 30, 2024

I wonder if you had been flirting with really low no3 for a bit

Formulator · May 30, 2024

ryanjohn1 said:
Strange occurrence. Bleaching could have come from bottomed out nutrients and high light levels. Corals weee hungry and ate all available or skimmer pulled everything. Do you feed the fish heavy or at least multiple times a day.

Low nutrients and high light doesn’t bleach corals overnight. And acropora love high light and lower nutrients. I’m convinced something nuked the tank as evidenced by the sharp ORP drop.

Lavey29 · May 30, 2024

Are they bleached with visible polyp extension or RTN and dying off?

Charlie the Reefer · May 30, 2024

Exactly guys, that's what makes me so puzzled. Like 10 dif acros got near completely bleached, and near everything was retracted/low polyp extension (except LPS). Thankfully I reacted so rapidly so nothing has actually died yet. But I suspect in a few days things will start to go because we know how SPS is.

I suspect that I WAS flirting with low NO3 for a bit, and even PO4. I feed on average 2 spirulina mysis cubes at dif times of the day to my main display, and one spirulina mysis cube to the other frag tank. Since dosing NO3/PO4 into good ranges it appears things are already taking a turn for the better. However, just how rapidly things deteriorated, and the rapid ORP drop at 1AM, leave me with some questions. Here is the latest ORP graph, it's back up which seems to be coinciding with better looking stuff.

What's really fascinating to me... is like.. actually what biological process and mechanisms are behind this. I have read the RHF articles on ORP, etc. What's going on! It's just a puzzle I want an answer to, but I understand these things are complex.

Charlie the Reefer · May 30, 2024

Lavey29 said:
Are they bleached with visible polyp extension or RTN and dying off?

At first they bleached with very bad polyp extension/retracted polyps. No visible die-off, that I can notice at least.

Now, they are just bleached with slight polyp retraction, but polyps appear to be coming back out. Some are definitely bleached a lot more than others, but again, it appears they are taking a turn for the better. We will see.

Charlie the Reefer · May 30, 2024

What am I doing - let me take some pictures! Lol.

Charlie the Reefer · May 30, 2024

So looking at these pics - it might seem I'm over reacting. But just such a sudden rapid brightening in color scared me. Really they used to be a lot darker and more colorful, especially these four pieces here. And polyp extension was MUCH better.

TSA Bill Murray

RR Bleeding Avengers

Greg's Unicorn (used to be shaggy, you can barely see polyps here IMO)

Monti. Hard to tell but this thing is way bleached compared to what it was a few days ago. Used to be much darker, rich color.

Sorry for quality of pics. Thanks for the discussion. I thought such a meaningful/interesting event warranted documentation and could result in some interesting thoughts.