Tank Crashing

[theguy67]

Hello everyone. I am experiencing some sort of ‘crash’ that I’m trying to sort out.

System: 13 gallon softy tank. Set up last summer from an existing 10 gallon.
Inhabitants: colt coral, sinularia, several mushrooms (over 30) 2 toadstools (small) and a frag of acans (only non-softy). Everyone has been doing great, with excellent polyp extension. One sexy shrimp and one emerald crab plus various small nerite snails.
Filtration: weekly water changes and HOB filter along with vacuuming of sand (crushed/large grain). I ran the nano before this one the same way without issue.
Feeding: alternate between reef chili and coral cuisine 1x per week

Parameters on 1/18/2026

Nitrate 0​

Alk. 8.6​

Cal 330​

Mg 1260​

Sal 1.025

Phos 0

pH 8​

Temp is 77-79 through the day
Ammonia 0

I noticed the alk and cal were drifting down compared to 3 months ago, so I dosed to increase a tad. I dosed over the course 2 days via the top off water fed by drip. Alk increased to 9.3, but calcium jumped to 560 (sailfert dilution test). Mg was also increased a bit to 1400.

Everything was ok until a couple days later when everyone was not opening as much, and each day it was just more and more closure until now everyone is closed.

Parameters on 1/23/2026

Nitrate 0​

Alk. 9.3​

Cal 560​

Mg 1420​

Sal 1.025

Phos 0

pH 8.12​

Temps the same 77-79
Ammonia 0

Since the reaction was slow, and I was gearing up for an ice storm, I didn’t test right away (another mistake).
I definitely overshot on the calc, rookie mistake. And I understand my alk is a bit high; however, it was running in the low 10s last fall so I let it drift down a bit. I wanted to raise alk to the low 9s and cal a bit as my acans were growing well until things dropped. I did a water change, Calc dropped to 485 after the above testing was done. Alk was 9.3. I didn’t test anything else that night.

Parameters on 1/26/2026

Nitrate 0​

Alk. 9.6​

Cal 475​

Mg 1400​

Sal 1.025

Phos 0

pH 8​

Temps the same 77-79
Ammonia 0

Above was a few days ago. Things didn’t look great but not awful. I figured I would just let things sit and hope it was a mild reaction.

I haven’t touched the tank, other than adding pure distilled water, as I didn’t want to shock it again. Just let everyone settle to the new numbers.

Today I sit as my mushrooms melt, my colt coral is sulking and my small toadstool melted at the base. I haven’t rested, but I did check ammonia, it is 0 still.

I’m very confused as to what’s going on. I don’t see precipitation (although it could be mixed with the algae bloom). It looks like a full system crash, but everything I read says a calc spike wouldn’t cause a huge stress event. And an increase of 1 unit of alk over 2 days shouldn’t be a big deal? Especially for softies? Ammonia is also 0. Was it a compounding of events? Ionic shifting in water chemistry causing global stress?

I’m doing a water change tonight. Just looking for possible theories at this point.

 

[wvned]

Could the power have gone off while you weren't there. I would suspect something like a temp swing over a slight shift in water paramaters for so many things to be affected and some hardy ones melting.
Carbon, water change and stability and hope it stops is your best course.

 

[griss]

Could the power have gone off while you weren't there. I would suspect something like a temp swing over a slight shift in water paramaters for so many things to be affected and some hardy ones melting.
Carbon, water change and stability and hope it stops is your best course.

This^

FWIW I’m dealing with a similar situation and my tank has been running since 2017 and I’ve been in the hobby since the 1980s. Unfortunately, these things sometimes happen.

 

[theguy67]

Could the power have gone off while you weren't there. I would suspect something like a temp swing over a slight shift in water paramaters for so many things to be affected and some hardy ones melting.
Carbon, water change and stability and hope it stops is your best course.

That’s what it looks like and ironically what I feared with the storm. I started seeing issues last week (like 1/20), and it was a gradual decline since. If I did lose power, I would have noticed my light’s timer being off schedule.

My only thought was maybe I set the tank’s heater in the mixing water bucket too long? But why would it be such a delayed reaction if temp did dip for a couple hours (max).

It’s sad, the Colt was so pretty.

 

[theguy67]

This^

FWIW I’m dealing with a similar situation and my tank has been running since 2017 and I’ve been in the hobby since the 1980s. Unfortunately, these things sometimes happen.

Thank you. I’m hoping I can discover what went wrong so I can move forward with this tank.

 

[griss]

Thank you. I’m hoping I can discover what went wrong so I can move forward with this tank.

That’s the tough part of this hobby, everything is going great and suddenly disaster. Years ago, I had a breaker trip and I ended up filling a 30 gallon trashcan with SPS skeletons. Almost all I had grown to basketball size from frags or small colonies.

 

[wvned]

I had an extended power outage. My tanks got down to about 73 by the forth day then the power came back on. 3 days later 90% of my xenia died and a few other things.
I think it is the extent of the deviation and not how long it happens that matters to some things.
And I could be completely wrong. I hope it never happens again to find out.

 

[theguy67]

I had an extended power outage. My tanks got down to about 73 by the forth day then the power came back on. 3 days later 90% of my xenia died and a few other things.
I think it is the extent of the deviation and not how long it happens that matters to some things.
And I could be completely wrong. I hope it never happens again to find out.

That’s fair. I also burned rice accidentally in the kitchen, although it was like 3 weeks ago. I also used a coffee filter to measure out the magnesium and calcium supplements. Maybe I stuck my hand in there after touching something toxic. I suppose a contaminant could have been introduced at some point.

 

[theguy67]

That’s the tough part of this hobby, everything is going great and suddenly disaster. Years ago, I had a breaker trip and I ended up filling a 30 gallon trashcan with SPS skeletons. Almost all I had grown to basketball size from frags or small colonies.

Ahhhh that’s tough. I couldn’t imagine dealing with that loss. This hobby is not for the weak. I do appreciate your support.

 

[wvned]

Over the years I have read many posts like yours. The truth is there are an almost infinite number of things that could do it. Many no one would ever think of.
thus my original post
Carbon, water change and stability and hope it stops....
A long time ago I had a heater fail and burn. I thought all I had to do was replace the heater. It decimated my tank.
No. Not a hobby for the week. 3 weeks ago we walked in and one of the eels was laying in the floor not moving. I pitched him back in the tank.
Dog hair and all. And waited.
He lived. You never know. Sometimes you get lucky.

 

[griss]

This is a good conversation for people new to the hobby to read. Stuff happens, things die, you either quit or forge forward.

 

[theguy67]

I have just completed a 2 gallon water change. I may schedule another in a few days as my theory is now leaning toward contamination, even if an increase in nutrients.

 

[griss]

I have just completed a 2 gallon water change. I may schedule another in a few days as my theory is now leaning toward contamination, even if an increase in nutrients.

As my friend @BrianD used to say, “dilution is the solution to pollution” or something like that.