Why did my acros suddenly bleach? ( detailed documentation)

[odyssey350kc]

As the title says I am trying to figure out why my acros bleached suddenly. Here is everything that has happened past week. Please let me know what you think was the most likely culprit so I don't make the same mistake again. FYI. I tested everything I have test kits for, I know I am missing some important stuff.

Friday 7pm : Added chemiclean to try and get rid of red cyanobacteria. Removed purit (carbon mixture) and let skimmer overflow because directions call for increased aeration.

Sunday 5pm : water test
Nitrate - 1ppm
Phosphate - 04ppm
Alk - 7.9
Calcium - 420
Temp 77.2
Ph 7.96
These numbers are very steady with where I have been keeping them for the past few months.

Sunday 6 pm: performed a 20% water change as per chemiclean instructions.
5 Gallons of the change trying to suck algae from rocks and 5 gallons siphoning 90% of the sandbed.
Skimmer still going crazy can't stop it from overflowing. Also replaced wetside of mp10 with a brand new unit. Rinsed off before adding.

Monday morning: I notice all 3 of my acropora are almost neon colored and their polyps fully extended farther than I have ever seen. Most of the other corals are at least partially closed or not looking good.

Monday noon: acroporas are turning a lighter shade. Everything else still looks bad
Replaced purit mesh bag with fresh stuff in case of chemical contamination.

Monday 7pm: 80% of the color is gone on acropora Everything else still looks bad. Frogspawn is breaking off little pieces and looks very strange.


Monday 8pm: setup skimmer to drain into 5 gallon bucket and use ato to put fresh mixed saltwater back to make up for water drained. Essentially performing a 2 hour 5 gallon water change using the skimmer.

Monday 10pm: water test to figure out what is out of wack.

Nitrate - 1.5
Phosphate - .03
Alk - 8.7
Calcium - 425
Temp- 77.5
Ph - didn't check.

Tuesday night: Acropora is 90% bleached, most other corals looking slightly better including frogspawn. Fish seem unaffected by the whole thing.

Possible causes:

Siphoning the sand bed - I have done this 3 or 4 times before without issue.

Alk swing of 0.8dkh - most likely from the water changes with a higher alk level and auto doser

Chemiclean - not likely but maybe

Microbubbles from skimmer?

If you made it this far thank you for reading everything. I think this is as detailed as I can get, hopefully I can figure it out. It is really disheartening when the tank has been doing good for months and this sort of thing happens.

 

[vetteguy53081]

Either a spike in ca/alk levels, lights too bright or swings as I see your alk numbers up and down, ph low and salinity should be 1.025 at 77-79 degrees
Mag 1300
Ph 8.1-8.3
Ca 440
Nitrate < .8
Moderate light and water flow

 

[Spare time]

What do you feed the tank and how often? My concern is that, if you stopped feeding what those corals need, they would easily be starved of nitrogen given you have realistically 0 nitrate.

 

[TheDragonsReef]

Ive heard of chemiclean wiping out some tanks. It is an antibacterial product and can cause some shifts in the microbiome of the tank. Ive used it on quite a few occasions and never had an issue though. I try to avoid using it cause unless you fix the nutrient issue the cyano will just come back after the treatment.

Aside from that id say nearly a 1dkh shift instantly could very well do it as well. Theres a couple possible causes here but i think its the combination of all of the changes that caused it. With my sps dominant tank i always make sure my newly mixed water is within 0.5 dkh of the tank water before doing a water change. I would not be using something like red sea coral pro that mixes at 11-12dkh on a tank i keep at 8 dkh.

 

[odyssey350kc]

What do you feed the tank and how often? My concern is that, if you stopped feeding what those corals need, they would easily be starved of nitrogen given you have realistically 0 nitrate.

I was feeding probably about 1/8 teaspoon of reef chili, coral frenzy and reef roids on an auto feeder 3 times a day. And a half cube of frozen mysis every other day. I reduced the auto feeder to once a day about a week ago.

 

[odyssey350kc]

Ive heard of chemiclean wiping out some tanks. It is an antibacterial product and can cause some shifts in the microbiome of the tank. Ive used it on quite a few occasions and never had an issue though. I try to avoid using it cause unless you fix the nutrient issue the cyano will just come back after the treatment.

Aside from that id say nearly a 1dkh shift instantly could very well do it as well. Theres a couple possible causes here but i think its the combination of all of the changes that caused it. With my sps dominant tank i always make sure my newly mixed water is within 0.5 dkh of the tank water before doing a water change. I would not be using something like red sea coral pro that mixes at 11-12dkh on a tank i keep at 8 dkh.

I had been working my alk up slowly over the past few weeks. Trying to bring it up about .1 per day up from about 7dkh. I actually have alot of issues going on, but the corals were all looking great. I had cyano and still am having what I think is a severe diatoms outbreak. And I have hair algae. I did have dinoflagellates a few months ago and this doesn't look exactly like that.

 

[Spare time]

I had been working my alk up slowly over the past few weeks. Trying to bring it up about .1 per day up from about 7dkh. I actually have alot of issues going on, but the corals were all looking great. I had cyano and still am having what I think is a severe diatoms outbreak. And I have hair algae. I did have dinoflagellates a few months ago and this doesn't look exactly like that.

Cyano may be due to very low nitrates