# [Wet Thumb Forum]-What would cause a sudden drop in oxygen?



## Yana (Apr 14, 2004)

I think it was a drop in oxygen, at least.

29G, cycled, nitrates 5ppm, kh 4 gh 6 ph 6.6. Moderately planted, mostly a variety of crypts, a few anubias, and dwarf sag that has run amok and covers about half of the tank. Temp 80 deg, light 80W, *no* CO2. Water changes every two weeks or so, treated with Amquel. The main issue with my water is that it's extremely soft -- kh 1 gh 1 out of the tap -- so I have crushed coral in the filter and I usually add baking soda at water change. I also add one ml of Flourish at water changes and every few days.

Last night, I did a small water change -- four gallons, I was sucking out the crypt leaves that melted when I changed a bulb. My usual waterchanges are about ten gallons. About five minutes after I had refilled the tank, there was an explosion of activity. The cardinal school (11) went crazy all over the tank, then hung at the surface gasping. All my shrimp came out of hiding too (and I very rarely see even one). There's a piece of driftwood that's so tall it breaks the surface, and six shrimp crowded onto this little tip as if they were trying to stay out of the water. The couple of shrimp that didn't find the driftwood just scrabbled at the water line. The labyrinth fish (1 betta, six pygmy sparking gourami) seemed completely unaffected, if a little startled at all the frantic swimming. Hence my guess regarding the oxygen.

I thought it was odd that the trauma didn't seem to occur as I was adding/immediately after I finished adding the new water. It was at least five minutes (through the opening segment of The Daily Show), then, BAM! Like flipping a switch. The only thing I did differently was that I added the four gallons out of the pitcher, each gallon separately treated with Amquel. Usually for ten or more gallons I fill up the rubbermaid, treat all of the water at the same time, then siphon it in. I tested the water immediately - kh 3, ph 6.2.

I lost four cardinals within five minutes. I removed the other seven, and all the shrimp, to a small container of fresh water (w/Amquel, of course) and they immediately calmed down, which I took to mean it wasn't necessarily my tap water itself. I then did a regular water change according to my usual method. kh 4, ph 6.6. Added an airstone, acclimated the cardinals and shrimp back in -- no hovering at the surface gasping at that point -- turned out the lights. This morning I had lost one more cardinal. The others seemed fine, if a little less energetic than usual. 

Any thoughts? Does a drop in ph lower the oxygen content of the water also? I had though Amquel worked instantaneously, is this not the case? My initial take-away is that I'm not going to be pouring in water gallon by gallon anymore... I've had this tank for five years and it's the first time this has happened, but not the first time I've done the gallon by gallon pouring.

I appreciate any comments you all may have!


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## sarahbobarah (Sep 5, 2005)

There IS a correlation, but for the life of me I can't remember the specifics.

Do you keep tabs on your city's water treatment agenda? Sometimes they add chemicals at certain times of the year.


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## imported_BSS (Apr 14, 2004)

No real insights. My only suspicion might be something that was inside the gallon jug? It sounds like some form of acid got into the tank, as evidenced by the low pH. Maybe something the gallon jug got washed with?

Purely guesses...
Brian.


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## sarahbobarah (Sep 5, 2005)

Ok, just reread the part about your tap water being ok (most likely).

"An acidic condition also corresponds to low oxygen levels. There is a direct correlation between pH and available oxygen. An alkaline environment provides literally thousands of times the oxygen needed for all bodily functions. Oxygen is essential to energy production. In very simple terms, natural energy production in the body boils down to oxygen burning hydrogen" -

I got this off a Cancer and Aging study. So yes, there is a correlation, and I'm agreeing with BSS that there may have been something in the gallon jug.

Hope this helps!
Sarah


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## Roger Miller (Jun 19, 2004)

Sarah,

I have no idea what the context is for the quote you gave from the cancer and aging study, but that statement is completely incorrect for aquariums and for water in general.

There is *no* general reason why oxygen and pH would be correlated. Dissolved oxygen and pH are unrelated to one another.

As to the original problem... With the sudden onset of symptoms I doubt that the problem was caused by a sudden drop in oxygen levels. It seems that something in the water you added was accutely toxic to your animals and probably damaged their gills. The lag time may have just been the amount of time it took the damage to set in.

The only cause that comes immediately to mind is that your tap water may have had an unusually high content of chloramine dissinfectants. I'm not sure how Amquel interacts with chloramine. Some dechlorinators may break down chloramine and leave quite a bit of ammonia in the water.

Chemical additives as a rule don't work immediately -- no matter what the manufacturer says. It's always a good idea to let things rest for a while after you add dechlorinator. When I do water changes I run all the water I need for water changes on 6 tanks into a large container, then I add dechlorinator and let it set for a half hour our so.


Roger Miller


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## Yana (Apr 14, 2004)

Thank you Sarah, Brian, Roger,

I'm definitely going to be much more careful when replacing water going forward, now I'm rather surprised that this didn't happen earlier in my five-year setup. I don't really let the water sit very long even when filling out of the rubbermaid container; I suppose the slower siphoning allowed time for the Amquel to take effect than pouring straight. Won't hurt to let it sit awhile in the future. The jug is aquarium-dedicated, by the way, kept in the stand cabinet and my family knows not to touch!

Roger, I looked up the Amquel, Novalek confirms it both breaks the chloramine bond and neutralizes the ammonia. I'd known it did something with the chloramines, as my water does have it. It sounds entirely possible that the concentration could fluctuate as Sarah suggests... Interestingly, the fact sheet, but not the bottle, says that Amquel will lower the ph in water with poor buffering - which mine definitely is, so there's another thing for me to track...

Thanks again to all.


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## sarahbobarah (Sep 5, 2005)

Roger,

I was thinking alon the lines of higher temp = lower DO = sped up metabolism = more fish waste = lower pH.

But now I realize that this prolly has nothing to do with Yana's current problem. Ah well - back to research!

Sarah


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