STN in SPS - possible relationship with Calcium/Alkalinity and high pH?

Ricardo Pinto

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Randy and other users of this forum,

I have a 150gallon aquarium with healthy SPS as you can see in this thread.

150g - "H2O+Something" Shallow Reef - https://www.reef2reef.com/threads/150g-h2o-something-shallow-reef.219899/

Over the last ten years I’ve been using your method “An improved 2-part solution” for supplementing Calcium and Alkalinity into my aquariums. In general, I had most success with it and I am a firm believer that your method is one of the best ways to add calcium and alkalinity in a balanced way into a reef aquarium.

However, I have changed from your method and started using Triton solutions since September ‘16 (initially I used Triton base elements and over the past two months I started using the Core7 solutions).

The change into Triton solutions was mostly because in July ‘16 I was adding 280ml/day of recipe #2 (of your 2-part solution) and I found that preparing and mixing the solutions was being too much time consuming at this point. I was doing 10L of 2-part solution every month and mixing the bicarbonate with water was starting to be very annoying (and I was using recipe #2).

So I’ve changed into Triton solutions mainly because I found that it was more easy to prepare the solutions than the 2-part, especially when I read the announcement of the Core7 solutions (which allegedly are 7x more concentrated than the usual 2 or 3-part solutions).

Between July and October, until I have changed into Triton solutions and got the right dosage, there were some Kh swings (between 8º and 6º dKH) and an increase in calcium (maximum of 460ppm at some point). At the same time I had lost a few SPS corals due to STN and took me a few months to get the aquarium into the right track.

Therefore, since October the KH levels and Calcium have been very steady between 6.4-7.0 and 410-430ppm, respectively. Nevertheless, every now and then I had a few STN in many SPS corals. What is most intriguing is that the STN appear at the same time (meaning the same day) in 4-5 corals (Frags or large colonies). The STN is mostly located at the base of the coral, and in most cases the upper part of the coral is looking very healthy.

Here are a few pictures of 4 corals of what happened 3 nights ago when I arrived home.










This was the fifth or sixth episode of STN over the past 2-3 months. In the beginning of December I thought this was some kind of infection that was proliferating in my SPS (something like “white band disease” syndrome), so I started to cut the lower part of the dead tissue to improve the recovery of the corals.

At the same time and because I don’t understand what was happening on those days when my corals were having the loss of tissue, this Christmas I decided to buy an Apex controller to have a 24-hour control of my aquarium. To my surprise I’ve noticed a variation of almost 0.6 degrees on the pH of my aquarium over a 24-hour period. Except the days when I perform water changes, it seems the pH of my aquarium varies between 7.85 and 8.45, as you can see in the APEX graphic below.



In terms of Alkalinity and Calcium there was also a strange variation although I did not change my daily dosage scheme in the last 30 days. During this week and preceding the STN there was a KH drop, it went from 7.0 to 6.4 and then recovered to 7.0, but the calcium had an inverse behaviour and raised from 400-410 into 425-430ppm, as you can see in the images below.

Alkalinity


Calcium



Taken altogether, I suspect the high Ph verified in a 24-hour period in my aquarium could be leading into calcium carbonate precipitation and consequently sudden changes in KH, and moreover leading into a KH-calcium imbalance.

1) Could this theory be the reason why I have STN in specific days and in several corals at the same time? Or is this a scenario where some sort of infection is most likely the cause of loss of tissue? I am thinking that it’s more a chemical problem than a bacterial/viral problem because the loss of tissue in my corals are very sudden. They are very healthy and growing in one day, and in the next one they lose tissue from the base. Or is it worse…. am I just being paranoid and I am seeing things where they don’t exist? :eek:... :D


2) What is the reason for the high pH verified in my aquarium? I usually don’t measure the pH in my aquariums, so I don’t know its normal values. I thought it was something between 8.0-8.2. And in particular, I always thought that if I was not using Kalkwasser the pH will not be so much increased. Do you consider 8.4 pH to be a problem? Or the 24h swing is most likely a problem?

Of note, I am a proud user of Jebao pumps. I have 2 x RW-8 for circulation, a DC3000 pump as my skimmer pump and a JECOD DCS 5000 as a return pump. I have heard the tungsten realising problems of Chinese pumps. Last October I have sent a water sample from my aquarium to be tested at Triton Lab and Tungsten was undetectable. I had a very low value of Iode and since then I have been dosing Triton Iode (4.7ml once a week).

Thank you very much for your advice and I’m sorry for the long post but this is a problem that I have been struggling for the last 6 months.
 

Stigigemla

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The pH is rising because of photosynthesis. The pH sinks because of organisms breathing. High kH will diminish the pH swings.
If You are using a salt with high borate content the usable kH content swing even more.
An algae refugium with opposite light period will diminish the pH sinking.
I would also consider sinking the light intensity but a few corals will fade in colour then.
A few fishes less will also make the pH sinking smaller.
And i would add some kH at least to 8.
(The high pH You measure could be wrong but I guess You have calibrated more than one time)
 

Randy Holmes-Farley

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pH 8.4 is no concern, but both coral calcification (skeletal growth) and abiotic precipitation increase as the pH increases. Many tanks run fine in the pH 8.3 to 8.5 range.

That said, if something else is causing STN, I can't rule out the possibility that that something else (a bacteria, a toxic metal, too low of low alk, etc.) might be causing a worse problem at higher pH.

FWIW, I'm not sure what these Triton solutions might be, but it isn't likely that their alkalinity solution is 7x more potent unless it is hydroxide, which would pH quite high unless doses super slowly like limewater (kalkwasser) is.
 

smh254

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Hi Ricardo did you ever get this figured out? I've been having a very similar.
 
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