My sps tank is crashing

[BriansBrain]

I’ve been dealing with this rtn/stn event for over a month now. It’s so dang disappointing to watch years of hard work and passion get thrown in the garbage. Seems like every couple of days that I come home from work, another colony is pealing that had looked to be struggling.

I just don’t know if I should cut my losses and throw out the struggling colonies to maybe stop the spread if it’s bacterial or something?

All stn started from mostly burnt tips, but some have just rtn pealed away.

My culprits I can put a finger on:

• Very low pH lows for several weeks. Lows of 7.6 to 7.55. Normally 8.3-8.1.
• High phosphate 0.60 (Hanna ULR phosphate). My system always seemed to run high though at 0.3-0.4.

Things to note:

1. I’ve ran an ICP and nothing negative of importance
2. I have not noticed any rusting deteriorating equipment
3. Alkalinity normally sits around 8-8.5 and the highest I’ve seen it spike to was 9.4 over a few days because I adjusted dosing daily down
4. I ordered (waiting to receive) a phosphate checker standard to cross check the accuracy of the checker itself. Maybe my phosphate aren’t actually that high. I’m running GFO thinking it’s high, but it’s actually very low. Just a thought.
5. I have no algae for being such high phosphates.
6. Only sps affected

I have a new system currently being built and was looking forward to filling it with these corals.

The last nice picture I have of this tank 5/26/25.

 

[bubbgee]

I am sorry to hear that. Did you do your ICP yet?
I am also struggling with random RTN and STN and so far I think it's a gyre that needed to be cleaned (low flow even at 100%) and adding carbon may have contributed. Some acros have stopped but some are far too gone. I am dosing FM STN/RTN X as well.

 

[eggie]

I think your main problem is alkalinity spike and maybe your either running GFO to fast or the tank is strip of phosphate thats what burn tip signs could be and its exactly what you describing

 

[Dburr1014]

I’ve been dealing with this rtn/stn event for over a month now. It’s so dang disappointing to watch years of hard work and passion get thrown in the garbage. Seems like every couple of days that I come home from work, another colony is pealing that had looked to be struggling.

I just don’t know if I should cut my losses and throw out the struggling colonies to maybe stop the spread if it’s bacterial or something?

This is what it seems like *most of the time. Burnt tips, flesh struggles and spreads. It doesn't stop until it's gone or intervened by something. That something could be chemical and manually cutting.

All stn started from mostly burnt tips, but some have just rtn pealed away.

My culprits I can put a finger on:

• Very low pH lows for several weeks. Lows of 7.6 to 7.55. Normally 8.3-8.1.

Has something changed in the house? IE; closed windows, more people/animals in the house, ect.

• High phosphate 0.60 (Hanna ULR phosphate). My system always seemed to run high though at 0.3-0.4.

Things to note:

1. I’ve ran an ICP and nothing negative of importance
2. I have not noticed any rusting deteriorating equipment
3. Alkalinity normally sits around 8-8.5 and the highest I’ve seen it spike to was 9.4 over a few days because I adjusted dosing daily down

A spike of 1dkh shouldn't do any harm in a healthy system. I think what happened here is your coral were suffering from something, that drives down building structure, and that drives up alk/cal/nutrients because the coral stops using it. Seems like you caught that it time to have such a low spike.

1. I ordered (waiting to receive) a phosphate checker standard to cross check the accuracy of the checker itself. Maybe my phosphate aren’t actually that high. I’m running GFO thinking it’s high, but it’s actually very low. Just a thought.
2. I have no algae for being such high phosphates.
3. Only sps affected

I have a new system currently being built and was looking forward to filling it with these corals.

I would definitely keep an eye on your alk and definitely turn the lights dimmer. I think 15 or even 20% is on order for a week or two.

 

[BriansBrain]

I think your main problem is alkalinity spike and maybe your either running GFO to fast or the tank is strip of phosphate thats what burn tip signs could be and its exactly what you describing

I’m not disagreeing at all, but I haven’t noticed a huge Alk swing this whole time. The most I’ve seen is around 1 dkh gain over a few days then I back off or shut down dosing.

I have brs gfo and run 1/2 the suggest amount in a media bag in the bubble trap of the sump. Before gfo (8/20) 0.60 and after (9/3) 0.39. But still, seems this is the issue

 

[eggie]

ALk spikes with low PO4 could be an issue
I have had higher Alk when I started my tank with low Po4 and had this issue burn tips and coral look burn
I run my tank at 7-7.5 the most and I have had Po4 @ 0.30 no issues
But Running GFO with low PO4 assuming it could be low corals start peeling and ALk that high is not good IMO

 

[BriansBrain]

Has something changed in the house? IE; closed windows, more people/animals in the house, ect.

Yes, it was the end of June/early July and very hot and the house was closed up. We had a newborn in that time, so maybe that’s it JK!

I would definitely keep an eye on your alk and definitely turn the lights dimmer. I think 15 or even 20% is on order for a week or two.

I did actually turn my light down but only like 10%.

What you described makes sense. Thank you. I usually have some issue during the summer it seems!

 

[BriansBrain]

ALk spikes with low PO4 could be an issue
I have had higher Alk when I started my tank with low Po4 and had this issue burn tips and coral look burn
I run my tank at 7-7.5 the most and I have had Po4 @ 0.30 no issues
But Running GFO with low PO4 assuming it could be low corals start peeling and ALk that high is not good IMO

yea I was thinking perhaps my Hanna checker was giving inaccurate readings and I ordered their standard for cross reference. I had .6 phosphate and maybe it’s actually lower and stripped it away.

On a side note, I called Hanna to ask them an estimate on how long/how many tests their checkers are good for/hold calibration. They said they don’t know. I understand the checkers are hobby grade but honestly pretty ridiculous response from them given Hanna’s background in the professional chemistry world.

 

[eggie]

yea I was thinking perhaps my Hanna checker was giving inaccurate readings and I ordered their standard for cross reference. I had .6 phosphate and maybe it’s actually lower and stripped it away.

On a side note, I called Hanna to ask them an estimate on how long/how many tests their checkers are good for/hold calibration. They said they don’t know. I understand the checkers are hobby grade but honestly pretty ridiculous response from them given Hanna’s background in the professional chemistry world.

I find them to be pretty good I use the Phosphate ULR and get 0.10 in my tank lately
just make sure the glass cuvet is clean no finger prints or water on the outside

 

[spsick]

Sorry to hear friend.

If it helps your confidence: when I ordered standards for my Hanna phos ULR it was dead on like 3-4 years in.

My recommend whenever someone is having stn/rtn is change RO carbon blocks and flush adequately before carrying out big water changes. It’s cheap insurance and can eliminate unknowns. Many people don’t realize how fast they get depleted and many others don’t flush them properly which fouls RO membranes.

 

[Z Burn's Reefing]

So sorry to see this. Hang in there. Happens to all of us and I know saying that doesn't really help.

9 times out of 10, I'd say this reflects alk swings, just my opinion. It is good to look for the rarer culrprits (i.e., stray voltage, leaching magnet, bad RODI filters/membrane, phosphate, rotting turbo snails, ICP with bad results, bacteria, double check temperature against another probe, etc.)...but if those check out, alk may have swayed on you more than you realized a few weeks back. Or even a month back...takes time for the damage to show, which I'm sure you know.

You clearly know what you are doing and have been at it for a while. All you can really do (I think)...is stop dosing all extras, keep alk super stable, make frequent but small water changes with a good salt, and make sure your RODI is running at peak performance (I don't care if the TDS is 0, change em out if its been a while). With time, small frequent water changes, and stable alk, you should start to turn the corner in a few weeks (crossing fingers).

 

[Dburr1014]

Yes, it was the end of June/early July and very hot and the house was closed up. We had a newborn in that time, so maybe that’s it JK!

It no joke, lol. High co2 in the house will drive down pH. If you don't already, have your skimmer pull fresh outside air.

I did actually turn my light down but only like 10%.

What you described makes sense. Thank you. I usually have some issue during the summer it seems!

Oh, and congrats on the baby!
I see you know how to frag yourself.

 

[BriansBrain]

Sorry to hear friend.

If it helps your confidence: when I ordered standards for my Hanna phos ULR it was dead on like 3-4 years in.

My recommend whenever someone is having stn/rtn is change RO carbon blocks and flush adequately before carrying out big water changes. It’s cheap insurance and can eliminate unknowns. Many people don’t realize how fast they get depleted and many others don’t flush them properly which fouls RO membranes.

Thank you. Good to know.

I did just change out all of my rodi filters two weeks ago. That was my initial thought of issues that chloromines were getting in from a city line flush or something.

 

[Dburr1014]

yea I was thinking perhaps my Hanna checker was giving inaccurate readings and I ordered their standard for cross reference. I had .6 phosphate and maybe it’s actually lower and stripped it away.

On a side note, I called Hanna to ask them an estimate on how long/how many tests their checkers are good for/hold calibration. They said they don’t know.

I think they are being honest.
@Lasse has a thread about alk regent in the fridge. Lasts longer. I just used an expired Dec 2023 regent to check my alk in the tank, after dosing a booster and my calrx effluent. They all seemed to be right. That's 1 year 8 months expired.

I understand the checkers are hobby grade but honestly pretty ridiculous response from them given Hanna’s background in the professional chemistry world.

 

[BriansBrain]

I think they are being honest.
@Lasse has a thread about alk regent in the fridge. Lasts longer. I just used an expired Dec 2023 regent to check my alk in the tank, after dosing a booster and my calrx effluent. They all seemed to be right. That's 1 year 8 months expired.

Thanks. Well not so much the reagent being expired, but I was curious how long their Checker itself holds calibration for since they can’t be calibrated. My phosphate checker is probably at least 5 years old.

 

[BriansBrain]

It no joke, lol. High co2 in the house will drive down pH. If you don't already, have your skimmer pull fresh outside air.

Oh, and congrats on the baby!
I see you know how to frag yourself.

It didn’t help my Kalk reactor and c02 scrubber were depleted at that time too. Further driving it down. I will say my wife’s awesome and will open windows and jokingly but seriously (I think) ask “how’s your pH doing?” Lol!

 

[Macdaddynick1]

Does your Ph really dips to 7.55 instead of 8.1 at night? If thats actually the case and not an issue with the probe I vote that or whatever causing that is an issue. People underestimate importance of ph because 99% of the time tanks run at a decent ph, but it’s perhaps the single most important factor in a reef tank IMO(especially for acros). Just to give you an idea If I’m correct I think that at 7.55 ph your tank water is 3-4 times more acidic than at 8.1. So your acidity is 400% higher which probably caused your po4 to go up due to your corals not growing like they are used to. I dissolve reborn media in my calcium reactor at 7 ph. If you grew those massive colonies at perfect ph range of 8.3-8.1, if they won’t die at 7.55 they would at least be super stressed to be killed by all swings. Then the panic kicks in on your end, and you start tinkering with stuff causing more RTN. Phosphate is not your cause it’s the result. Get that GFO out and leave your po4 alone. What is are your nitrates at ?

 

[CHSUB]

Reef biology states that corals with growth are not necessarily of good health; it is well known science that high nutrients affects coral health. Introduce an unknown stressor to corals in a high nutrient environment will liking have bad effects.

Yes, the current trend is following “the guy” with some nice corals, a loud voice, and high nutrients vs known researched science. I’m thinking your high po4 is one of a few liking causes, including low pH.

 

[sjfishguy]

I would say the phosphate swing. This exact thing happened to me. Alk swing then added gfo, disaster. Turn the gfo off immediately. That was the only thing that helped me turn my problem around. Took a month but the bleeding stopped.

 

[BriansBrain]

Does your Ph really dips to 7.55 instead of 8.1 at night? If thats actually the case and not an issue with the probe I vote that or whatever causing that is an issue. People underestimate importance of ph because 99% of the time tanks run at a decent ph, but it’s perhaps the single most important factor in a reef tank IMO(especially for acros). Just to give you an idea If I’m correct I think that at 7.55 ph your tank water is 3-4 times more acidic than at 8.1. So your acidity is 400% higher which probably caused your po4 to go up due to your corals not growing like they are used to. I dissolve reborn media in my calcium reactor at 7 ph. If you grew those massive colonies at perfect ph range of 8.3-8.1, if they won’t die at 7.55 they would at least be super stressed to be killed by all swings. Then the panic kicks in on your end, and you start tinkering with stuff causing more RTN. Phosphate is not your cause it’s the result. Get that GFO out and leave your po4 alone. What is are your nitrates at ?

Nitrates are currently 14. Attached are my trends for nitrate, phosphate and alkalinity over a year. The up and down phosphate spikes are clearly bad and that from GFO usage trying to bring it down from going up.

I did totally remove gfo today. I added gfo 8/27 and today another colony RTN. Like you, I’m thinking it’s part of the issue.

The pH graph shows the low for a week of the lowest 6/30-7/7. The lowest low was 7.58, I mistakenly put 7.55, but regardless very low. I calibrated my pH probe 6/20.