Wierd pH Issues
My tank's pH has been having some strange readings, and I'm not entirely sure how to deal with it. The water out of the tap in my dorm reads around 7.6, but the water in my tank tests 8.4 consistantly. I've been adding 1.5mL API pH Down after every test I've done (which has been roughly every day or two since I set the tank up almost a month ago) where the pH has been higher than preferable, but the reading the next test is the same +/- .1-.2.
Thanks in advance for any help/thoughts/advice!
You have to question what's in the tank for substrate and perhaps rocks as something must be raising the pH.??? Is there some kind of coral in there?
First thing, I'd question the tap water pH reading. Did you out-gas the CO2 before testing? CO2 levels in tap water can be high, and this acidifies the water, causing a lower-than true pH reading. Take some tap water, shake it very vigorously for a couple minutes to out-gas the CO2, then test the pH. You may find it is higher, but this will be accurate.
Second, never use pH adjusters in a tank with fish unless you know exactly what the GH and KH are. The KH (carbonate hardness or Alkalinity) acts as a buffer to maintain a stable pH--which will be what comes out of the tap--and unless you reduce the KH the pH is going to bounce back every time. Until the point is reached where you have exhausted the buffering capacity, and then the pH can suddenly drop, killing the fish due to the significant shock.
The pH is tied to the hardness, as you will find explained here:
After you've checked the tap pH as above, you will either know the tank is normal at the higher reading, or you will know there is something calcareous (sand, gravel, rock as AD mentioned) raising it above the tap water pH. At that point, if you desire to lower it (depends upon the fish) the GH and KH will have to be dealt with first, and/or the calcareous material will have to be removed if present. But before you go into that, tell us the fish species; some are fine with what you have.
Thanks guys! At the moment, I have two male guppies, three ghost shrimp, plus however many snails have colonized the tank at the moment. It's currently set up with run-of-the-mill natural colored petco pea gravel, a piece of lava rock, and a piece of fake mopani driftwood, plus two Anubias, a floating Java Moss ball, three planted Wisteria, several patches of Dwarf Hairgrass, a crypt of some sort, some Dwarf Baby Tears, and a sword of unknown variety.
And I didn't out-gas the CO2 - I'm so new to this that it's not even funny! I'll read the article, retest the tap pH, and get back to y'all :)
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I'll be offline shortly until tomorrow, so I'll just offer a couple comments from what you've already posted. The lava rock is calcareous, probably, but not likely to the extent indicated though it might contribute. But we need those numbers before going further on this.
Second thing is the fish and shrimp will be fine whichever, they are medium hard basic pH water creatures so there is not need to adjust the pH or hardness, whatever it may be. Here again, the tap pH confirmation will help, as removing the lava rock might be useful depending.
Just tested the pH after out-gassing and it read somewhere in the 7.8-8.0 range, so that definately factored into the difference. After thinking about my last post, I relized that the dwarf baby tears are ancored to a second piece of lava rock and dunno if it matters or not, but there's also an air pump hooked up to an airstone that I keep on 24/7. I'm glad to know that the current pH shouldn't hurt the fish! Also don't know if it'll help any, but here's a pic of everything at the moment:
Thanks so much for the help!
You could leave things alone and the named fish and shrimpo are OK with that. Or you can remove the lava rock which may be raising the GH and corresponding pH slightly. If this was in a tank of soft water fish where you were working to keep the GH and pH low, something like the rock would be significant; here is is minimal.
We haven't mentioned GH and KH, those numbers for the tap would be worth knowing. With fish, hardness is actually more of an issue than pH in most cases. I'm not suggesting there are any issues here, but I like to know my tap water.
I seem to be having similar issues. I'm on well water from a farm so my nitrates are around 30ppm out of the faucet if I'm testing correctly. The pH does the same thing too. I tested all of my rocks for alkalinity and found nothing.
As I read about the CO2 out-gassing in this thread I jumped up and tried it myself and sure enough after a few minutes of shaking a container full of fresh water the pH slowly raised. Does it usually take a while to out-gas?
As I understand sudden pH changes of 0.3 or greater can be harmful to fish? (My fresh water is around 6.5 then eventually raises to around 8.2 in tank!)
If this is going to be an issue for people like pitti and myself, would keeping a barrel of heavily aerated water on hand for water changes be a solution? I would need a clean 50 gallon drum, dual nozzle air pump, air tubing, 2 large air-stones. (This also works for de-chlorination if you dont want to pay for conditioner)
My tanks fluctuate with each water change by about .3 or .4 and in 20 years I've had no issues that I'm aware of from this. There is also the normal diurnal fluctuation that occurs in nature and in planted aquaria: the pH lowers during darkness as the water acidifies from the increasing CO2, then during the day the pH rises as the CO2 is used up. The GH is sometimes affected too, depending upon the plant load and light. This 24-hour shift is harmless, and as I mentioned, it does occur in natural waters too, though not usually to this extent because there are many more plants per volume in most aquaria.
I would not have a change from 6.5 to 8.2 within the space of a day. If these numbers are accurate, smaller-volume water changes more frequently rather than one massive change would be better.
Back to the issue, this is one option, the other being the more frequent with less volume water changes.
So I'm not sure I understand all of this yet, but it's getting there :-p But so long as the water isn't hurting the fish, I don't think I'll do anything to change it. That said, and as weird as it probably sounds, I would like to figure this out in case there's ever a point that the parameters do need adjustment. How do you test for GH and KH - do I have to contact the city for a water report?
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