corals look bad every second day

[Elliot_17]

Hi,
I´m Jojo and I have a problem....
I keep corals for something like 10 years now but this is something I havent seen before! In my little coral farm (4 shallow tanks with 900L combined and a lot of coral (1000+ frags)) nearly all corals show signs of stress exactly every 2. day. One day everything is fine and on the next all LPS and many sps have no polyp expansion anymore. Especially goniopora, alveopora, euphyllia, pocillopora, blastomussa and some rhodactis are effected by this phenomenon. Acropora seems to be uneffected...
I have rouled out pretty much every conventional explanation: Kh and ph are no different on a good and a bad day, dosing and light are also the same. I even did an Icp on a bad and on a good day, no difference...
I am dosing the max ammount (16ml) of ATI Nutritions N and P every day because there are not many fish in the system. My Po4 is around 0,03, Nitrate is around 1... those values are stable. I dont see how the low values could explain the bad polyp expansion on one day and the good expansion on the next.
For my alkalinity and calcium I´m using Balling light (600ml for alk and 200ml for calcium). Also I run a UV with 20w and activated carbon...
In search for an answer ich focused on the lights because I thought of ligth stress but that wasnt the solution either. One tank is lit by t5 and the rest by Orphek Atlantic (3. generation) and philips coral care (2. generation). And on the bad days, the corals look better in the evening compared to the morning. That rules light stress out for me...
Do I have a big error in my thinking somewhere?

Maybe someone here has an idea because I really don´t anymore

And sorry if my English isn´t perfect, I´m from germany and this took quite some time to write but this problem needs some international help


That is a good day... Everything looks normal.

Alveopora and turbinaria on a bad day....


And the whole system, for you to get a feeling for the whole thing.

 

[blaxsun]

If this is consistently happening every 2nd day, my thinking is it's something you're dosing or doing the day prior.

 

[shakacuz]

also, does this happen at specific times? i second possible dosing causing this change but it could also be a drop in PH(or rise?) or something along those lines as well.

do you have anything that turns on or off? like a skimmer on a timer

 

[Elliot_17]

Thanks for your fast replies!
Yes, it´s happening very consistently, every second day. I already suspected my dosing pump (GHL) but as far as I can tell, there is nothing wrong with it.
I´m dosing nothing but Balling and ATI Nutritions. And Alk is double checked with a kh keeper. Im testing it 3 times a day. There is a slight change in alk over the day because of consumption during day and a slight change in ph but both occure on good and bad days in the same intensity.
There is nothing on a timer... Evereything runs 24/7 .

 

[Dkmoo]

Process of elimination- Pause everying you do for 1 day - dose, feed, light, etc.. if now your "every 2 day" cycle shifted by 1 day, then you know its something you did there that caused it. If thebl frequency didn't shift. Then you know its something else you haven't factored.

 

[Elliot_17]

The elimination idea seems like it could work. But it has to be planed very well because I cant stop dosing alk for example. Even without light, that would be a drop of at least one degree... Everything else should be no problem...

 

[Koh23]

Noticed something similar on my lps - mainly euphilias, but also on softies - mainly sarco and leather....

One day, all great, size, polyp extension, second day - half open and extended. Not on such regular basis, but, two days is great, then one-two-three is not, then again great.

Since i dont dose anything beside phyto, i guess there is some "x factor", unknown fluctuation, maybe food, something....

But, since they all visibly growing, and i have no idea on what, why... I just leave it alone....

 

[Sly Element]

i had something similar, and did 2 ICP tests from Fauna Marin (located in Germany).

I did see heavy metals were to high because of dosing.
After a noticed that, i stopt dosing and did a couple of waterchanges.

I let it run without dosing minerals etc. And after 2 weeks, the problem was gone.

So it couyld be something like that.

 

[elysics]

Is there something happening outside those cellar windows every second day, someone dumping cleaning water on the street at the end of the day? Or some other contaminant