pH 8.1 to 7.0

[Icthyological Person]

I my 29 gallon tank my pH is 8.1 and everything else is fine, other than a slightly higher ammonia due to recent fatalities (3 cories and an oto). i was wondering if I could use API proper pH 7.0 to lower it. I know of course, that pH swings can be more detrimental than not ideal pH, so i am thinking maybe twice a week ten percent water changes replaced by 7.0 pH water. I know it says not for use in planted tanks, but could I use if I just did it in a water change and not dose the entire dank as the directions say?

 

[jsoong]

Short answer - NO.

Water with pH of 8 has a high level of buffers (like 300 ppm). The buffers will work hard to keep the pH where it is. Adding things like pH down will not do anything until you actually overwhelm the original buffers in the water. This will require a lot of pH down (or any other buffer). Even after you got it down, you need to have an overwhelming amount of the second buffer (pH down & the other pH altering chemicals are just buffers - usually phosphates that has a different equilibrium pH) to keep pH stable. If you use just a little bit of the pH down (like what the package advices), the original buffer just overwhelms it after a few hours & the pH reverts, so you end up with yo-yo-ing pH.

My suggestion is to leave the pH alone. If you must play with the pH, the best thing to do is to REMOVE some of the buffer (ie use a R/O unit) or mix in a bit of distilled water with your tap. I would suggest you play with the pH in a bucket (without fish) until you get a good feel of how your intervention is going to behave. Incidentally, your idea of mixing water to pH of 7 using pH down then using that to slowly drop the pH in the tank will not work. Even if you get the mix water right, mixing 10% into the tank gets you into the inadequate 2nd buffer scenario so the pH will not be stable at all.

But the easiest thing to do is simply to leave the pH alone.

 

[Icthyological Person]

Short answer - NO.

Water with pH of 8 has a high level of buffers (like 300 ppm). The buffers will work hard to keep the pH where it is. Adding things like pH down will not do anything until you actually overwhelm the original buffers in the water. This will require a lot of pH down (or any other buffer). Even after you got it down, you need to have an overwhelming amount of the second buffer (pH down & the other pH altering chemicals are just buffers - usually phosphates that has a different equilibrium pH) to keep pH stable. If you use just a little bit of the pH down (like what the package advices), the original buffer just overwhelms it after a few hours & the pH reverts, so you end up with yo-yo-ing pH.

My suggestion is to leave the pH alone. If you must play with the pH, the best thing to do is to REMOVE some of the buffer (ie use a R/O unit) or mix in a bit of distilled water with your tap. I would suggest you play with the pH in a bucket (without fish) until you get a good feel of how your intervention is going to behave. Incidentally, your idea of mixing water to pH of 7 using pH down then using that to slowly drop the pH in the tank will not work. Even if you get the mix water right, mixing 10% into the tank gets you into the inadequate 2nd buffer scenario so the pH will not be stable at all.

But the easiest thing to do is simply to leave the pH alone.

Thanks for the advice, that's what I'll do.

 

[Bigzmey]

Second to leave pH alone, pH 8.0 is fine.

 

[Icthyological Person]

My fish are fine in 8.1, I'm just glad I asked here first or I would get a real headache and school and extracurricular activities give me enough.