help with my acropora, 1 by one are dying

[j.a.c.wester]

as the title is saying. I am starting to lose a lote of corals all of a sudden. First I lost a nice big pink tip acropora. Then i lost 2 acro millepora from RTN. I discoverd that my refractometer was not good and bought a DD ocean, calibrated it with RO water and discoverd my salt was to low. 1.019

so I used my topoff water to ad salt to my system. Now a lot of corals are showing STN and a sh*t load of them died of RTN

My system

Tank 120x60x65cm (water 57)
sump 100x40x40cm ( water 20)
fragtank 60x80x30 ( water 25)

Light

2x kessil 360WE
1x kessil 160WE

1x kessil 160WE on the fragtank
color 40% power 75% ramp time up and down both 180Min total light time from 9:30 till 22:00

flow

maxspect gyre 150 at 80%

filter techniek
ATI powercone skimmer
biopellets
active carbon

suplements

triton base dosing
2x a day


water

no3= 5
no4= 0.03
kh= 8.95
ca= 425
mg= 1400

fish

chelmon rostratus
tang
2 clown
Henkie
3 gobies
2 dragon gobys
2 dragonface pipefish
2 cleaner shrimp

I got the following acropora and millepora ( still alive)

4x millepora digitata
2x plate millepora
3x acropora nana tricolor ( 1 showing STN had to frag it)
2x acropora millepora ( 1 half died of RTN)
3x seriatopora
2x acropora frogskin
1x acropora desalwii
1x blue typ acropora white/brown base





The order the where added to the system is as follows.

the where added in 3 steps everything not specified are from the beginning

fase one

the pink ( RTN)
acropora millepora (RTN)
acropora nana (STN)

fase two

2 pink millepora ( half RTN, 1 OK)
2 purple millepora ( 1 RTN, 1 OK)
1 yellow millepora ( 1 RTN)
1 blue acropora dont know the name ( OK)
2 desalwii ( both STN but moving realy slow)
1 frogskin yellow ( STN stopt, i think)
2 acropora nana tricolor ( OK, only lost color but getting it back)
2 millepora digitata ok



fase three

acropora enchinata (RTN)
frogskin green is ok butt lossing a bit color
acropora blue tip white/brown base had a acropora eating crab.

Now dont think, holy ..... where is he leving al these corals. The are small. like max 6x6x6 cm and a couple where to give away as a gift.

Unfortionetly i discoverd after these additions that for the past 9 months my tank was running on a 1.019 sg and not at 1.025. the first RTN started after the last fase. the last one that was getting RTN last night.

How do i stop The STN? Is it the flow, is it becaus of the low selinity i had.

I am going crazy over this. All corals come from the second fase from a transhipping from bali.

 

[catman78]

so I used my topoff water to ad salt to my system.

how fast did SG rise?

 

[71xlch]

You had corals that were stressed from your salinity being to low. Salinity was bumped up to where it should have been to fast and the already stressed acros died.

With a change in salinity you get a change in the big 3 as well. So alot of changes to fast is the answer. I would keep the salinity and the other 3 in balance and possibly somethings may be saved. Stabilize your water parameters for a month or two and things should turn around.

 

[j.a.c.wester]

It took me 10/11 days to get the salinity to the current level so lets say 1.0005 a time.

 

[tmc1313]

I discoverd that my refractometer was not good and bought a DD ocean, calibrated it with RO water and discoverd my salt was to low.

You should not calibrate a refractometer with RO water. It should be calibrated with a standard solution. It should never be calibrated at zero. Doing this is too far off the linear range of where we keep our tanks salinity and you can get a large margin of error.

 

[j.a.c.wester]

also important to mention. I used from salifert the 35 grams solution to check the calibration.

 

[SDangerfield]

Maricultured corals can RTN/STN with the slightest fluctuation in parameters.

 

[SDangerfield]

Aquacultured corals are your best bet if your parameters fluctuate at all. They are more hardy.