Montipora are bleaching after water change!

[Eggpaul]

Hello everyone, I have had my tank for 2 years and my montipora have been growing like crazy. Everything was perfect. Last week I noticed a gonipora was closed up so I decided to do a large water change. It's a 150 gallon tank. I usually do 30 gallon changes.
I did a 75 gallon change, and the next few days I noticed a lot of my montipora bleaching. I shut off the gfo and carbon, and the bleaching continued. I changed my gfo and carbon, and the bleaching continued. Help!!!!

Only changes I made recently are... purchased a 65 gallon Norwesco tank for water changes (that's how I did the large water change).

Salinity 1.025
Nitrates 10
Calcium today 465
Kh. (This was around 6 after the water change, and I moved it up to 8.15)
Phosphates 0

I use instant ocean salt. I dose calcium and alkalinity.

Can it be from the large water change which dropped the KH very fast??

I washed the norwesco tank with vinegar and water before using it.

Another possibility... I took out 75 gallons by mistake, and then put in 65. So I had to mix salt water and added some within 30 min and more in the morning. Maybe the salt wasn't fully dissolved and it hurt the coral? But all the other coral are fine.

 

[Auquanut]

It may be a combination of things. Hopefully we can get some more eyes on it.

 

[hyprc]

You say your alk went from 6 to 8.15dkh? In what span of time? Nutrients seem a little low, water change would drop them further (undesirable).

 

[HB AL]

Params in new water were probably quite different than the old water and the large water change was enough to stress the corals, that’s the simple explanation.

 

[Dragon8736]

Could be something in the water it didn't like.

 

[DSC reef]

You say your alk went from 6 to 8.15dkh? In what span of time? Nutrients seem a little low, water change would drop them further (undesirable).

Nailed it, if this was instant then that would be the source IMO

 

[HB AL]

Params in new water were probably quite different than the old water and the large water change was enough to stress the corals, that’s the simple explanation.

And was about to do my 1st water change in 2.5 years next week just because, well you helped me change my mind.

 

[Bryce M.]

+1 to the sudden change

 

[Eggpaul]

You say your alk went from 6 to 8.15dkh? In what span of time? Nutrients seem a little low, water change would drop them further (undesirable).

I moved it up in 2 days. from 6 to 8.15

 

[Eggpaul]

Nailed it, if this was instant then that would be the source IMO

But it's not the first time I have done a large water change. One difference is I calculated the pump output and removed 75 gallons when I only had 65 gallons. So I had to add a few gallons of RO water (which wasn't heated), and then quickly mixed some salt and added that. Temperature dropped fast a few degrees because the new batch wasn't heated. Dumb mistake. hope they can come back. The red Monti is all white now, and the green Cap is getting there too.

 

[Eggpaul]

Params in new water were probably quite different than the old water and the large water change was enough to stress the corals, that’s the simple explanation.

I guess I have to start matching DKH in my water change too?

 

[hyprc]

I moved it up in 2 days. from 6 to 8.15

That'll tick a lot of stuff off... Last time I had a drop that low I brought it back up to 8.0 over the course of 5 weeks.

I guess I have to start matching DKH in my water change too?

Everything in your salt mix should be at least close to tank params.

 

[LAReefer4Life]

Sorry to hear about your troubles. Your nutrient levels are very low, specifically phosphates. You really should NOT be using GFO if your PO4 levels are at 0. GFO in combination with the abrupt raise in ALK is a for sure bet on why you experiencing bleaching issues. How often are you feeding? Do you target feed any corals?

 

[gtrider]

i agree with @pathot984

I also agree that the change was too drastic. Does the salt you use match your parameters?

 

[vetteguy53081]

System shock from:
Salinity too high/low
Alk swing
Temperature swing

 

[BeejReef]

I can empathize. Sucks when u pump out more water than you have on hand. If it were to happen again, I would just turn off the return, move the heater to the dt, and let the ph'ds provide your flow for 12 hours while you mix more salt.

 

[Neoalchemist]

Any alk swing in a tank with zero po4 likely will cause this. Alk swings are bad but survivable, very low po4 is bad but survivable.
But combine the two conditions and, well you can see the result.
In my experience very low nutrients cause corals to be significantly more sensitive to parameter shifts.

 

[Neoalchemist]

I can empathize. Sucks when u pump out more water than you have on hand. If it were to happen again, I would just turn off the return, move the heater to the dt, and let the ph'ds provide your flow for 12 hours while you mix more salt.

I always leave my last bucket of waste water hanging around until everything is up and running in case something happens or I miss calculated. I just pour some old water back in if I come up short.

 

[kidrobotny]

def shocked the system, maybe the temp change

 

[Eggpaul]

Sorry to hear about your troubles. Your nutrient levels are very low, specifically phosphates. You really should NOT be using GFO if your PO4 levels are at 0. GFO in combination with the abrupt raise in ALK is a for sure bet on why you experiencing bleaching issues. How often are you feeding? Do you target feed any corals?

I use a Hannah test kit for the P04, and it's always 0. I feed 2 frozen cubes at night, and if I have live worms I throw a bunch in there also. I need to target feed the corals more often. I hadn't fed the corals in a few weeks. it's a 150 gallon tank with 15 fish (blue jaw trigger, fox face, copperband, blue star wrasse, yellow banded wrasse, flame hawkfish, 2 clowns, diamond goby, mandarin goby, blue pygmy angelfish, firefish, purple firefish, bicolor blenny, resplendent anthias). how much should I be feeding to make P04? I have a refugium in the sump. I turned off go4 and carbon a few days ago.