Corals RTN-ing and cannot find the cause

O

ojonas81

New member
Over the last couple of days some of my corals have RTN and I cannot find an explanation to it. I do have an ich outbreak in the tank but not treating any fish but trying to catch and move them to hospital tanks. The RTN-ing started before I tried to catch any fish.

Did a complete water test yesterday and nothing really sticks out. Any ideas would be helpful.

Sg: 1.028 (slightly high but is coming down slowly)
Alk: 7.7
Ca: 385 (slightly low but not terrible bad. Working on getting it up to 430 range)
Mg: 1400
NH3: 0.00
NO2: 0.00
NO3: 0.50
PO4: 0.1 (would like it slightly lower but not too bad)

Will bring water sample (both tank and RO/DI) to my LFS today to verify my measurements as well.

I am out of ideas. Ich should not have an effect on corals as far as I understood it. Thankful for any help and ideas.
 
I'm not the expert on sps but i do know from my research that your alk is a little low would be better around 9-12. Your ca should be in the 400-500 range and like you already stated your SG should be brought down to 1.023-1.026 range
 
Had my water being tested at my LFS this afternoon and for the most part they had the same readings as I did. Main difference was the alkalinity which I have constantly measured to 7.7 using my Red Sea test kit (bought this year and has not expired). The LFS got two separate readings of 10.2 and 10.3. That is a big difference from what I got but I do not know if it is my kit or theirs that is bad. Regardless since I have been measuring constant values all along no major fluctuation of the values has happened regardless if the true value is 7.7 or 10.2. Both are within a "normal" range too.

Here is a picture of the tank taken on 7/11 (last FTS before the crash).

_MG_4019-Edit.jpg


Since the picture I have removed all the Jebao WP-XX pumps and replace it with a MP40 instead. SO much better and more reliable flow.

Here is also a link to my build thread if needed: Build thread
 
With that high sg and low ca it's possible that's the problem. Especially if your alk is really 10.5 ish

Just not balanced
 
If your sg has been high for awhile sps will and can do weird stuff. I recently went thru high sg and I lost one acro to rtn all other 50 or so not affected. But that made me run tests and I figured out it was my sg. With that said I had a suspicion by the look of my corals that something had been off for awhile.
 
Did some checks and found that I had a little stray voltage in the tank. Think I narrowed it down to my reactor pump (not all of it but a lot). That is the only item (besides the heater which I tested too) that runs off AC and are submerged in the tank. All other equipment runs either off DC (return, skimmer etc.) or mounted outside of the water (MP40 etc.). Could stray voltage, even if it is not much, be a cause for RTN?

I do agree that the SG is high (currently at 1.027) and the CA low (currently at about 400). I like to run SG at 1.026 and CA around 430.
 
Look for pests. Nobody thinks that they have them and more people do than they thought. Turkey base the bases and see if anything flies off.

Put the top of the heater above the water line - it will help.
 
Well, since the ground probe has been installed I detect no stray voltage in the tank. Hopefully it is not too late.

Have not seen any pests on the corals. Used my macro lens and magnified them and no obvious signs of anything unusual.

I am concerned that my Red Sea alkalinity test kit showed about 7.7 dHk when the Salifert ditto used at my LFS showed 10+ dHk.
 
hopefully the lfs has a bad kit. at the same time 10alk is not bad at all. range is 8-12 im running 10.5 right now and getting great growth.

unfortunately you are going to have to purchase another kit.
 
I am not do worried about the numbers coming out from the kits as the stability is more the key and bot 7.7 and 10.5 are within accepted range. But at this point I don't know which one to trust. Contemplating getting a Hanna alkalinity and just trust it.
 
ojonas81 said:
I am not do worried about the numbers coming out from the kits as the stability is more the key and bot 7.7 and 10.5 are within accepted range. But at this point I don't know which one to trust. Contemplating getting a Hanna alkalinity and just trust it.
Click to expand...

One thing to consider here is that the difference between 7.7 and 10.5 is really a big difference, so my view would be to infer that one of the test kits is just wrong, not that it is functioning at a different calibration. So I'd consider rethinking the assumption that if you were consistently getting 7.7 that your system was stable the whole time, the test kit could just be totally useless, and you might not even be getting a real reading. 7.7 might not mean anything. I think that another consideration as you tighten up your system parameters is that you wouldn't want an alk swing that big. I doubt the 7.7 reading, but for the future when you are confident in the readings you are getting, I suspect that a swing of 7.7 - 10.5 would likely cause RTN, because SPS need not only proper parameters but also, and I think more importantly than any specific level, STABLE parameters.

I've been trying to figure out my own causes of RTN/STN and I'm working through some fixes to my system as well, so Good Luck!
 
Got a new test kit for alkalinity (Salifert) and confirmed that my Red Sea one is garbage. Shows about 4dHk too low.

At the moment my levels are at:

Ca: 426 ppm (Hanna Checker)
Alk: 10.9 dHk (Salifert).

Will try to lower the Alk slowly to around 9 where I would like it but very happy with the Ca level. Still have some STN going on but hopefully it will stabilize soon and go the other way.
 
Imbalances usually only make coral grow out skinny or not grow at all unless the parameters are dangerously high which yours are not. Do you run GFO? If not you should add some in a reactor and then you can sit back and watch the phosphates drop. Also, what lighting are you running.
 
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