Recovering From Acropora Damage Due to Nutrient Instability

george9 · Sep 30, 2023

Hello everyone,
Unfortunately dealing with one of my first “big” acropora issues since delving into keeping these finicky corals in my 32g Biocube.

All summer I had kept my alk between 7.4-7.8 and things had been taking OFF. Added a airstone Co2 scrubber in July as I had co2 issues in the morning with ph bottoming around 7.6. Ran this alongside my crappy Biocube protein skimmer than really hasn’t been running too efficiently lately. this brought pH into the 7.9-8.2 range. Anyways, growth had further taken off after this scrubber addition and things were fantastic. I was dosing All for Reef once per day, and as the alk demand kept creeping up, this became somewhat of a sizeable dose for my small tank. I went from around 3ml daily before the co2 scrubber to around 15mL daily over a couple weeks. Fantastic. For whatever reason I decide I want to run alk closer to 8.3 to give me more of a buffer. I run PO4 in the .06-.08 range and NO3 around 5-10PPM so thought this wouldn’t be an issue with a slow raise. WRONG. This is where my issues began. Alkalinity slowly rose from in the mid 7s (7.5-7.8) to the low 8s (8.0-8.2) over about a week and a half, and by mid September I was topping out at 8.5-8.6, which is the highest I was comfortable taking it. It took me until a month later after this change, to realize my Bill Murray colony wasn’t getting larger white tips from growth, it was actually a slow bleaching. Hmm, this was odd to me because I had a decent level of nutrients for this alk level, so what was happening? Well, I tested alkalinity every 24 hours. This appeared to be stable, BUT I failed to account for my massive AFR dose which spiked the alkalinity a few points after I dosed. This meant when I tested alk at 8.5 and dosed, it actually increased to around 8.8 to even 8.9 with a one time daily dose before dropping back down again 24 hours later. THIS was the heart of my issues began I believe, but not where the damage stopped.

September 19, I do my normal 10% water change and test the params about 30 mins after. Phosphate was .1PPM…just as I like it. I come home around 4PM, around 4 hours after the water change to a monti cap shedding skin, a closed stylo, and the bill murray had less polyp extension and was noticeably lighter. Somehow, PO4 had dropped from .1 to .03PPM, which has caused me HUGE issues with RTN in the past and this time was no exception. I dose Po4 back up to .1PPM and immediately the polyps on the stylo come back out, and the damage stops on the monti cap. I attribute the slow damage on the bill murray that was almost imperceptible for a period of time due to too many water changes leading to lower nutrients (nitrate also lowered to around 3PPM) at the higher alk level, so it was slowly starving. When the po4 rapidly dropped, since the colony is in high light and alk that potentially spiked to 8.8 after dosing, it took a substantial hit. It has reduced polyps during the day now, but does have more polyps out at night as well.

Now I am dosing both All for Reef and phosphate on a doser and this has kept things very stable for the last 5-6 days. Po4 remains .1 PPM which is what I am targeting, and I am very slowly dropping alkalinity back into the mid 7s. I’m taking it extremely slow and am running 7.9-8.0 right now. Yet things still are slowly getting worse it seems, although nothing is going downhill too rapidly.

Another of my best growers in high light started showing slow STN from the base a few days after the PO4 event, which makes sense. This acro was also growing into zoanthids, which I think exasperated the issue so I placed a rock between the zoanthids and the acro to avoid them touching anymore. You can also see lightening on the encrusting base of this acro on the areas receiving the highest light. This area has also gotten slightly larger between Sept 19 and today.

At this point, I am holding the line, feeding a lot, keeping parameters as stable as I can and hoping for a full recovery. Despite regaining stability for a week, things have still gotten slightly worse. I have removed activated carbon and turned off my skimmer since I am always running on the low end with nutrients, I don’t think I need the skimmer right now. Especially since I get better aeration from the air stone co2 scrubber. What else can I do to mitigate damage? The bleached colony cannot be moved to low light as it has been established for a while and has encrusted. I also have minor burnt tips on an oregon tort. All of my other acros in lower light been unaffected,
I am only seeing damage on the 300+ PAR areas.

MY BIGGEST QUESTION NOW - Should I lower my entire tank lighting intensity and risk putting everyone else in jeopardy? And if so, how much can I lower lighting at one time? Or is there a chance for recovery in its current place with stable parameters since this wasn’t lighting induced in the first place.

As always, thankful for any advice!

george9 · Sep 30, 2023

Ended up lowering the peak intensity by 3% and hopefully that helps at least a little bit with the (now) stable parameters. I’m so nervous to do anything drastic because largely, things are looking pretty nice other than the acros.

Lavey29 · Sep 30, 2023

I would have just opened a window or added a room fan to get fresh air circulation to help the PH drop. Nothing you can do but hope now and keep everything as stable as possible to see if recovery occurs. I had a spike to that killed off a nice acro colony some months back. I removed the whole piece. Now a miniature tiny piece of the same acro is basing out and sprouting up. It's like it's DNA remained on the rock or something.

george9 · Sep 30, 2023

Lavey29 said:
I would have just opened a window or added a room fan to get fresh air circulation to help the PH drop. Nothing you can do but hope now and keep everything as stable as possible to see if recovery occurs. I had a spike to that killed off a nice acro colony some months back. I removed the whole piece. Now a miniature tiny piece of the same acro is basing out and sprouting up. It's like it's DNA remained on the rock or something.

In south florida opening windows is not an option in the summer :/ I think the co2 scrubber has done nothing but help the tank, it was me foolishly thinking I needed to run alkalinity a little higher that caused this (coupled with too many water changes and Rox carbon AND my runaway PO4 lol)

The scrubber really hasn’t led to any sort of instability on its own but did require I increase my dosing. Prior to the scrubber with low pH, my tank was consuming less alk than even the recommended starting dose for All for Reef!

Dom · Sep 30, 2023

george9 said:
Ended up lowering the peak intensity by 3% and hopefully that helps at least a little bit with the (now) stable parameters. I’m so nervous to do anything drastic because largely, things are looking pretty nice other than the acros.

I think you have the right approach. And I would suggest:

Make one change at a time. Success after multiple, simultaneous changes makes it impossible to know which change or combination of changes were effective.
Be patient and keep your changes gradual.

george9 · Sep 30, 2023

Dom said:
I think you have the right approach. And I would suggest:

Make one change at a time. Success after multiple, simultaneous changes makes it impossible to know which change or combination of changes were effective.

Be patient and keep your changes gradual.

Will do. I think my ultimate goal is to return to the alkalinity to the mid 7s back where everything was happy with my nutrient levels. Things weren’t too too bad in the mid 8s until that rapid PO4 drop…just awful timing. Starting this tank with dry rock has been the bane of my existence keeping PO4 elevated. I have been slowly adjusting my doser down a couple tenths of a mL each day so it slowly nudges towards the mid 7s.

Now that my dosing won’t spike the alkalinity with my doser, I think that is a huge part of the equation solved.

Dom · Sep 30, 2023

george9 said:
Will do. I think my ultimate goal is to return to the alkalinity to the mid 7s back where everything was happy with my nutrient levels. Things weren’t too too bad in the mid 8s until that rapid PO4 drop…just awful timing. Starting this tank with dry rock has been the bane of my existence keeping PO4 elevated. I have been slowly adjusting my doser down a couple tenths of a mL each day so it slowly nudges towards the mid 7s.

Now that my dosing won’t spike the alkalinity with my doser, I think that is a huge part of the equation solved.

I think you would be most successful doing water changes.

Remember:

Water changes help our tanks thrive. And they do this by exporting the buildup of nitrates and phosphates.

But water changes also allow you to keep stable water chemistry as it replaces elements consumed from the water column by the tank's inhabitants.

FAITHFUL, WEEKLY 20% water changes will go a long way in getting and keeping your tank on track and thriving.

So on a 32 gallon tank, you're looking at 6.4 gallons per week.

I would do 10 gallons every 10 days.

george9 · Sep 30, 2023

Dom said:
I think you would be most successful doing water changes.

Remember:

Water changes help our tanks thrive. And they do this by exporting the buildup of nitrates and phosphates.

But water changes also allow you to keep stable water chemistry as it replaces elements consumed from the water column by the tank's inhabitants.

FAITHFUL, WEEKLY 20% water changes will go a long way in getting and keeping your tank on track and thriving.

So on a 32 gallon tank, you're looking at 6.4 gallons per week.

I would do 10 gallons every 10 days.

I agree with this but I have already been religious about water changes, doing about an average of 4 gallons per week but am going to back off doing them since my nitrates were also on the lower end of what I prefer. My acros looked best at 10-12PPM NO3 with alk at 7.5 dkh and PO4 .08-.1PPM.
Maybe going to do every 10 days to 2 weeks rather than every 7 days. I do this primarily to keep nitrates down, and I have to add PO4 to the water to prevent rapid PO4 drops like I recently experienced. If I don’t match the PO4 in the water change water to the tank, that upsets the balance between what’s soaked in the rocks and water column and leads to PO4 instabilities. This most recent PO4 drop, I did a water change, cleaned the sand a bit, changed the ROX carbon and did not add enough PO4 to the water change water which sent the PO4 plummeting within hours of the water change. I don’t even use GFO (or wouldn’t even dream of it). This tank soaks PO4 up like a SPONGE!!

Prior to this issue, everything had been thriving and really coloring up with twice weekly trace element and iodide dosing. I use regular purple IO and drop the alk to match the tank prior to the water change. according to my last ICP in July, I was lacking in some smaller trace elements and iodine despite increased AFR dosing. Dosing a few drops of Iodide a week and about a capful of Reef Trace per week (which coincidentally contained all of the traces I was low on) has been a game changer for coloration…until now. Hopefully I get this issue behind me and we can get back to those colors lol.

This is a classic case of a reefer (me!) thinking they need to make changes when there is absolutely nothing wrong…and it backfiring in their face lol

Dom · Sep 30, 2023

george9 said:
I agree with this but I have already been religious about water changes, doing about an average of 4 gallons per week but am going to back off doing them since my nitrates were also on the lower end of what I prefer. My acros looked best at 10-12PPM NO3 with alk at 7.5 dkh and PO4 .08-.1PPM.
Maybe going to do every 10 days to 2 weeks rather than every 7 days. I do this primarily to keep nitrates down, and I have to add PO4 to the water to prevent rapid PO4 drops like I recently experienced. If I don’t match the PO4 in the water change water to the tank, that upsets the balance between what’s soaked in the rocks and water column and leads to PO4 instabilities. This most recent PO4 drop, I did a water change, cleaned the sand a bit, changed the ROX carbon and did not add enough PO4 to the water change water which sent the PO4 plummeting within hours of the water change. I don’t even use GFO (or wouldn’t even dream of it). This tank soaks PO4 up like a SPONGE!!

Prior to this issue, everything had been thriving and really coloring up with twice weekly trace element and iodide dosing. I use regular purple IO and drop the alk to match the tank prior to the water change. according to my last ICP in July, I was lacking in some smaller trace elements and iodine despite increased AFR dosing. Dosing a few drops of Iodide a week and about a capful of Reef Trace per week (which coincidentally contained all of the traces I was low on) has been a game changer for coloration…until now. Hopefully I get this issue behind me and we can get back to those colors lol.

This is a classic case of a reefer (me!) thinking they need to make changes when there is absolutely nothing wrong…and it backfiring in their face lol

4 gallons on a 32 gallon tank is is only 12.5% and not big enough in my view.

If this problem has developed suddenly, I'd look at external events. Have you used scented candles in the room? Any aerosol use in the room (air freshener)? Did an exterminator make a visit to your home recently? Any children? You would be surprised at the things kids do.

I call your attention to my signature, line item 3: "don't fix what isn't broken".

george9 · Sep 30, 2023

Dom said:
4 gallons on a 32 gallon tank is is only 12.5% and not big enough in my view.

If this problem has developed suddenly, I'd look at external events. Have you used scented candles in the room? Any aerosol use in the room (air freshener)? Did an exterminator make a visit to your home recently? Any children? You would be surprised at the things kids do.

I call your attention to my signature, line item 3: "don't fix what isn't broken".

I am pretty sure I've narrowed it down to how I was dosing alkalinity, plus the raising alkalinity, plus the PO4 issue. With growth taking off, my AFR dosage was increasing and despite raising to almost 15mL a day, I continued to dose once per day. This meant I'd test alk in the morning, and then dose 15ML immediately after. When I tested alkalinity prior to dosing and then a couple hours after dosing, I discovered that this one time 15ML hit of AFR spiked the alkalinity of the tank about .3DKH which is not a huge deal if my alkalinity was below 8. But, at this time, I was also slowly pushing alkalinity upward. So when I would test at 8.6 one morning, which was the highest it got to about two weeks ago, I then dosed the 15mL, this could have spiked my alkalinity to 8.8dkh before returning to around 8.5 by the next morning when I'd test again. This gave me a false thinking that alk was remaining stable when it wasn't. This repeated yoyoing at the higher alk led to the beginning of the bleaching, but the nail in the coffin was the rapid po4 drop. I didn't catch this issue until last week when I installed a doser. Looking back at my data, I didn't see a noticeable lightening of the bill murray mini-colony until a few days to a week after I initially pushed my alkalinity above 8. As I continued to hold alk above 8, and continued once daily dosing, things slowly got worse. I didn't even realize I had a problem UNTIL the PO4 also bottomed out which caused RTN in a monti, and led to a more rapid lightning. To be quite honest, the bleaching was so slow up until the PO4 drop that I thought it was just larger growth tips due to the higher alkalinity.

My doser now doses 6x daily and after testing alk multiple times through the day, it has remained stable.

edit - Also wanted to add that I think I am on the right track with this reasoning because the monti cap is pretty rapidly improving now with the changes,

Dburr1014 · Oct 2, 2023

I'm pointing the finger at po4 dropping rapidly.
AFR is supposed to release slowly. An alk spike of 0.3 is not to bad. I have spiked 1dkh multiple times. My po4 runs at 0.1 and no3 is still undetectable with hanna since April. (upped my feeding tremendously since)

Is this a dry rock start and how old is the system? The rock will soak/store/release as needed and if it's a dry rock start I would understand. But if an old system I don't understand how that would happen unless it was po4 depleted for a while.

george9 · Oct 2, 2023

Dburr1014 said:
I'm pointing the finger at po4 dropping rapidly.
AFR is supposed to release slowly. An alk spike of 0.3 is not to bad. I have spiked 1dkh multiple times. My po4 runs at 0.1 and no3 is still undetectable with hanna since April. (upped my feeding tremendously since)

Is this a dry rock start and how old is the system? The rock will soak/store/release as needed and if it's a dry rock start I would understand. But if an old system I don't understand how that would happen unless it was po4 depleted for a while.

That’s kinda what i’m scratching my head at, maybe I have been PO4 depleted for a bit. Although I have been testing PO4 daily, so I am not sure.

I went though a period dosing crazy amounts of neophos last year when the tank was newer and It stabilized around early 2023 but I think with weekly water changes and only dosing PO4 once per day, coupled with not dosing enough po4 into my water change water, it has led to me being lower in po4 over time than I imagined.
I will say, to maintain my PO4 at .1PPM using my doser for the last week, i have had to dose 5-6ml of neophos per day which is around .04-.05 PPM of PO4 in my water volume if their dosage is correct. That is far more than I ever dosed in a day the past couple months. I am starting to notice my po4 stabilize the last 2 days and I’ve decreased the dose to around 3-4ml per day to maintain .1PPM now.

As for the AFR alk spike, I agree and it wasn’t an issue for me when I dosed all at once while running alk in the mid 7s. As soon as I hit 8.5, doing a one hit of AFR hypothetically could lead to a spike to the upper 8s, which coupled with lower nutrients (no3 was getting below 5ppm as well) and a severe sudden drop in po4, caused the rapid decline I saw over the last 2ish weeks. The decline was slower and almost unnoticeable through the beginning of September (before my rapid PO4 drop) but I bet the repeated spikes into the upper 8s while dosing once a day is still part of my issue while the rapid PO4 drop while they were already slightly stressed made the damage evident almost instant.

My 15mL dose of AFR is “supposed” to supplement around .8-.9 DKH, So it makes sense that I only saw a smaller spike instantly rather than a .9dkh spike right away. The rest of the alk was slowly released over the course of 24 hours I suppose.

It was a full dry rock start, in November 2021. Now that I have po4 on a doser, I am a lot more relaxed knowing it cannot bottom out as easily. I am totally fine if it gets a bit higher than .1PPM, because that is WAY better than letting it get below .03 which is where issues for me begin.