something is wrong with my SPS

[yajur]

On May 18th my dosing pump full dosed flourish nitrogen can be 200ml for sure.

i have not seen it for 18hrs then my digi for RTN so checked and found that my dosing pump went bad.

After that i check no3 and it less than 1ppm , so i done 160 liters of water change and for next 48hrs all went good and then on 3rd day my setosa got STN so fragged it can able to save few frags from it.

And today my lime in the sky stag getting brown in colour so i again tested No3 i can able to see 0.5ppm of no3 only .

Alk : 9
Ca : 350ppm
Po4 : 0 in hanna 0 in salifert also
no3 : 0.50 in salifert and 0 in api
mg : 1300

so today i done another 160 liters of water change cant figure out the exact issue is.



My no3 and po4 is zero used two different kit to confirm it but my calcium is low 340-350ppm but iam not sure is this cause brown in sps.

What cause browning of sps ?

 

[yajur]

Here the photo of lime in the sky

Top image is before the incident and bottom is after it.

Sent from my SM-N9208 using Tapatalk

 

[71xlch]

Not sure what your tank size is, but changing that much water without parameter matching is just another stresser to the coral (I'm guessing you didnt parameter match, if you did disregard). Second your Calcium is on the low side which is a stresser as well. Last but not least having 0 nitrates and phosphates is not a good thing. Do some reading there are a ton of people who are dosing nitrates now improve colour. No food and a lot of stress = a coral that needs a ton of zoox in its skin to feed and stay alive.

 

[yajur]

Not sure what your tank size is, but changing that much water without parameter matching is just another stresser to the coral (I'm guessing you didnt parameter match, if you did disregard). Second your Calcium is on the low side which is a stresser as well. Last but not least having 0 nitrates and phosphates is not a good thing. Do some reading there are a ton of people who are dosing nitrates now improve colour. No food and a lot of stress = a coral that needs a ton of zoox in its skin to feed and stay alive.

tank water vol is 2000 liters.

 

[71xlch]

So a ~8% water change. Parameter matching not really and issue then. But 200ml in 530 gallons isn't a ton and a total of ~16% change in water is not going to remove/dilute it that much.

I'd personally make sure you have a bit of trates in your system and keep water stable. Colour should come back. If there is enough light and stability i find acros have a hard time not growing.