High Alk & Ca while pH Drops, Healthy Fish Dying Overnight

[kdragon64]

I'm having an issue with my tank that I can't figure out. It's happened to me twice in the past, then seemed to fix itself and tank was stable again. Seems to occur about once every 6-10 months.
Checking every week or two at the most and getting steady parameters as below:

salinity 35 ppt
pH 8.0-8.1
alk 9-10
Ca 460-480
Mg 1350-1400
Nitrates 10-20
Phosphates 0.05-0.3

I have 125 gallon tank with about 140 total volume water.
I am auto dosing 2-part and have not changed the settings other than minor tweaks of no more than 10%.
I auto dose NOPOx and have made gradual changes to dosing to adjust for increasing nitrate and phosphate.
I run cartridges of Purigen (changed about every 3 months) and activated Carbon (changed about monthly).
I have air line run from outside to the intake of the protein skimmer.

Problem:
About two weeks ago, I noticed the alc and Ca were rising, to 11 and 480-500, respectively, so I cut the dose, pH was still around 8.0-8.1.
About one week ago, alc and Ca continued rising, to 12 and 500, respectively, so I cut off the doser all together, pH was still around 8.0-8.1.
This week, alc and Ca remained at around 12 and 500, but pH dropped to 7.7 and otherwise several very healthy looking fish died overnight and a few other were breathing hard.
I suspected potential oxygen depletion, although I currently don't have a kit to test that.
So, I ran the fan on the sump continuously for 2 days.
Luckily, the remaining fish recovered and the pH went back up to 8.0 within 2 days.

However, I don't know if what I did running the fan helped or if the situation corrected itself, as this seems to be what happened before on this seemingly regular cycle every 6-10 months.

Your insights and suggestions will be greatly appreciated.
Cheers.

 

[MARK M. DAVIS]

You definitely need a better water gas exchange if the fish are breathing hard. Break surface tension by aiming a power head upwards. I use 2 gyres to get major surface agitation. Skimmer function also effects. Fans okay but, usually good for cooling. Make sure your test kits are good using a second opinion kit. Do you have coral to consume alk and calcium? That alk is high but, not enough to kill fish. Make sure air line to skimmer has some filter and isn’t close to exhaust from cars or other .

 

[kdragon64]

Thanks Mark, all great advice and I agree with all. Only problem is, I also have two gyres as well as two circulating returns that agitate the display tank, and skimmer running all day except for 15 minutes a day for feeding. No redundant test kits, but I generally use red sea and test another tank that tests fine at the same time. I also have plenty of coral to consume alk and Ca, and does so on a regular basis, but it doesn't seem to be consuming during these past several weeks. If cycle repeats as before (last time was about 8-10 months ago) it will start consuming again. Also, air line to skimmer is not near exhaust, but what kind of filter would you put on the airline? Still confused about the cause of this.

 

[MARK M. DAVIS]

Fish death will cause Ammonia spike. Do you remove dead fish? Carbon filter on the exhaust line.

 

[Mastiffsrule]

Hey KD. Sorry for the loss.

From your numbers I did not see anything glaring that would cause fatalities so quick. The CA and KH are off but would be more of an issue for coral than fish. I would not expect O2 saturation as an issue with your pumps. Usually that is only an issues when dosing meds or things like chemi clean. Mark also had a great point about the airline, but sounds like you ruled that out.

Any reason u suspect O2? Usually a lack of oxygen will start to show with the fish gasping near the surface. If you have test kits for NH3 it could not hurt to check.

Maybe someone else may have some other insight.

 

[kdragon64]

Cool, I'll get a carbon filter for airline, just in case.

Dead fish are removed as soon as I can find them, but that doesn't explain the first one, plus wouldn't ammonia spike cause pH to rise, not fall?

I was thinking H2S build up, but there are no noticeable bubbles nor any noticeable smell of rotten eggs, but that would explain the briefly lower pH, temporary oxygen depletion, fish gasping, and otherwise healthy fish death.

However, I have less than 1 inch of sand and plenty of snails and sand sifter moving it around. Perhaps the overflow vents are clogged and holding stagnant water? Will check those when I get home.

 

[Mastiffsrule]

Sorry, Was not clear also if there were any new livestock additions. Any signs of disease or scratching. I would lean more to a disease or parasite than water quality unless something got into the water unknown to you.

The PH 7.7 to 8.1 is a swing but should be tolerated by the fish if. It depends on when you are testing it also. Ph drops overnight so if you test in AM it will be lower than PM. Before lights out.

 

[kdragon64]

No new livestock, no signs of disease at all, healthy one day, dead the next, always test pH at night.
Did not think the pH itself was a major problem, but was thinking that whatever caused the pH to drop while the alkalinity was higher as a potential cause.

 

[Mastiffsrule]

No new livestock, no signs of disease at all, healthy one day, dead the next, always test pH at night.
Did not think the pH itself was a major problem, but was thinking that whatever caused the pH to drop while the alkalinity was higher as a potential cause.

I normally run high alk in the 11-12.5 range and ph around 7.8. I agree something may have happened to cause the symptom so to speak but was not the disease.

I cannot say 100% and hopefully someone else will chime in. I was thinking possible some type of bloom that depleted o2. But again it sounds like you have good circulation to fight that off.

Any chance the NoPox could have been overdosed?

 

[kdragon64]

I totally appreciate the ideas, and it's possible something is growing behind the rocks, but otherwise just dealing with a mild bubble algae issue that I can see. The NOPOx is also a consideration, but I've been using it for quite awhile, at least 6 months now, and with current nitrate around 20 and phosphate around 0.3, it seems I should be tweaking the dose higher if anything.
Really at a loss to pin this issue down.

 

[Mastiffsrule]

Hang in there.. keep an eye on things and let’s hope someone else may have afresh angle of approach on this.

 

[kdragon64]

Will do, thanks again for your insight!

 

[ADAM]

Not sure what can cause an issue of dying livestock seemingly so quick and also seemingly to be on a timed schedule also. However a build up of organics can cause low pH with high Alk (battled this for a while myself) but in your case the pH only showed to drop a small amount suddenly and fairly quickly came back to your tanks normal.

In my personal reef experience education I would think that it was/is some outside force or chemical that caused the issue. If nothing much has appeared to change in the system, as far as livestock and additive additions there's not much that one could come to blame.So, every 8-10 months..... any services that are performed on an annual or bi-annual basis for your home? If your home is under a service agreement for things like HVAC or Pest Control the chemicals used may have entered through your outdoor air line and then been quickly diminished my the carbon and purigen. I would imagine some species could have more pronounced reaction to certain chemical(s) as well, therefore the corals were affected by lowered/ blocked Ca/Alk consumption, snails seemingly OK, but the vertebrates (fish) took a big hit and some couldn't recover. The next question is what chemical could do that? Now, maybe a Pest Control Co didn't apply anything to your home but maybe you could've used some type of household cleaner, body cream (hand lotion, soap, etc), or some type of aerosol spray that somehow made it into the tank either by airborne means or could have been on your skin and into the water..... Pest control products come to mind due to the organophosphates (phosphorous) use in their products, I'm sure there's plenty of products that use some for as well. Pest Control comes to my mind because of the timing of your issue and visual evidence you've noted.

The phosphorous form mentioned in the passage below is what made me think a pesticide could be to blame. This form would possibly effect the nervous system of the fish fast enough to cause major damage before biologic degradation of the compound or removal through your chemical media(s).

*Credit to authors mentioned.
1. Jonathan Newmark, in Clinical Neurotoxicology, 2009

PATHOPHYSIOLOGY
Like organophosphate insecticides, nerve agents act primarily as cholinesterase inhibitors.
_____________________

2. Tracy J. Eicher, in Clinical Neurotoxicology, 2009

Organophosphates
Organophosphates (OPs) are present in nearly 40% of all pesticides used in this country. They are highly lipid soluble and are easily absorbed through the skin and respiratory tract.
_____________________

Very possible this isn't the cause, but after reading over the thread a couple times, this chemical just popped into my head all of a sudden so I figured Id share.

Good luck and update us with anything you find.

 

[ADAM]

P.S.
From what I gather many of the potential products would become acidic when introduced to water, maybe the cause of your temporary pH drop? Also, some ophthalmic medicines are a top search hits when searching for products utilizing organophosphates.

 

[Engloid]

Are you doing water changes, testing your ri water, then your salt mix? If your ro unit fails you can add tap water alk to the salt alk and wind up raising alk in the tank with waterchanges

 

[Triggreef]

I have to agree with @ADAM on most likely scenerio being outside contamination. None of the info you posted points to anything really. On a side note to his comment ... Do you have dogs or cats? Say your wife may have used some flea and tick control on them, you unknowingly pet the animal, and later work on your tank.

Also a couple questions. How long has the tank been running?

Why such a small sump? I'm guessing a 20g sump since you said total volume 140g.

If you could get a bigger sump maybe a fuge with opposite lighting would help your pH swing at night.

I really don't think pH is the cause of your issues though.

Also prior to this incident what's the last maintenance preformed?

One last thought, what's a normal water change for you? Using salt newly mixed without giving it several hours to dissolve before using it can cause your exact issue.

 

[petraio]

I would. Not use Purigen anymore just past experience made water srystal clean but some that not test could reveal what happens to the livestock stock just a monthly water change a much better approach

 

[kdragon64]

Thanks all for some very good things to consider.

I don't think my problem has anything to do with lawns being sprayed, since I live in SE Pennsylvania, and it's pretty cold for people to be doing that kind of yard work. I'm also quite careful not to introduce any unwanted chemicals into the tank, and wash my hands before they go in there. I do water changes about 1x per month about 20 gallons each time, which probably should be more often, but that's usually as often as I get to it. My sump is actually oversized for my tank, 125 gal tank and eshopp's sump rated for 300 gal, but I have a lot of rock, which leaves my water volume to be about 140 gal by my rough estimation. The tank is over 2 years old from first set up. Socks are changed and parameters measured once a week. General clean up maintenance is done with my water changes every month.

I now think my problem is possibly linked to Adam's comment, "However a build up of organics can cause low pH with high Alk (battled this for a while myself)," since it looks like there its a build up of gunk inside my overflow panels between the vents on the bottom face and the top openings. Unfortunately, I've been overlooking those during maintenance. And, I'm not sure how to best get in there to clean them out.

My faceplates don't open like some overflows.

Does anyone have a great way to effectively clean those overflow channels out without totally blasting the stuff into the tank?

 

[kdragon64]

I've also heard mixed results for Purigen, but thought I would be safe using it, since I don't recycle it at all, only use fresh media every 3-4 months. But I've been considering doing away with that too the more I read. That savings can go to restocking once I'm comfortable with a solution.

 

[kdragon64]

Also, forgot to mention, no chemical treatments in the house, the wife goes nowhere near the tank, and we have no other pets, besides my second tank.