What causes the PH to drop?

[12 Volt Man]

10% WC every now and then is no problem as is no WC for a few weeks.

But if no WC or 10% WC are your long term operatings basics then you will have problems in a year or so with a medium stock in a tank.

I disagree with this. you will have problems pretty quickly doing that sort of maintenance schedule.

I have seen it a million times while testing customer's water when I was at the LFS.

if you don't change water or change very little per week, assuming normal stocking and feeding, you run into trouble fairly fast.

once you are on a regular weekly schedule the problems (high nitrate, low ph) generally disappear.

 

[Deaths Sting]

The PH scale is logarithmic, meaning each whole number above (or below) 7 is 10x larger (or smaller) than the previous…

Therefore the difference between 5 & 6 is 10 times larger than the difference between 6 & 7... And the difference between 4 & 5 is 100x larger than the difference between 6 & 7...

Therefore the difference between 4.5 ~ 6 huge...

wow, i never knew that! that's pretty important to know and understand, thanks for sharing that piece of information with us!

I disagree with this. you will have problems pretty quickly doing that sort of maintenance schedule.

I have seen it a million times while testing customer's water when I was at the LFS.

if you don't change water or change very little per week, assuming normal stocking and feeding, you run into trouble fairly fast.

once you are on a regular weekly schedule the problems (high nitrate, low ph) generally disappear.

+ 1

 

[Toby_H]

on another point a PH of 5.5 or lower the bacteria needed to convert AMM to Nitites begans to die...so your AMM levels should have shown something?

I have "heard" many times that low PH is bad for bacterial colonies...

Yet my local water has an exceptionally low KH (near 0), a fairly low PH (6.5) which easily decreases...

Some of my aquariums that have a lot of driftwood semi frequently fall in the 5.5 range of PH and I've never had issues of detectable ammonia in mature tanks under these circumstances...

I have no "science" to dispute the above quote with... Yet I've also never read any true "science" to support it... Therefore I am not saying it is wrong, I'm only saying I do not agree that it is universally true...

 

[Bderick67]

Great thread alot of good info here. My water supply has very low kH. As a result even with 50% weekly changes I found the kH would drop to zero along with the pH dropping. I tried adding crushed coral but with the water volume and frequency of water changes it did very little. Adding baking soda works well, you need to be careful though, add only small amounts and test frequently. I took me about three weeks to get to where I had my kH at a stable desired level and I can now add that dosage at each water change.

 

[12 Volt Man]

I used to run into old tank syndrome during busy times at university.

I had overstocked tanks with big fish that ate a lot

I would do a big water change, and by the end of the week, the pH would gradually drop to "yellow" on my test kit, which was 6.0 or below. right after a water change it was closer to neutral (bluish).

my tinfoil barbs would develop cloudy eye/fungus like symptoms by this point.

I would do a big water change (usually late at night after studying lol) and the pH would come up and the symtoms would disappear overnight. they were just sensitive to low pH (from a buildup of wastes).

I remedied the situation by putting a small bag of crushed coral in my aquaclears.

this buffered the water enough that it didn't drop by the time the week was up, so when I did the weekly water change the pH had not had time to drop and everything was fine.

to this day, I still have a bit of crushed coral in my AC's (eg. on my current 150 you will find one there) lol. its a good luck charm I guess LOL

that was how I eliminated old tank syndrome without having to do massive water changes every day. the coral enabled me to do water changes weekly and be fine, even with overstocked tanks..with decent sized hungry fish

 

[Mr Pleco]

Here are some links to Articles by Timothy A. Hovanec, Ph.D
For those who'd like to dig a little deeper on this subject.

http://aem.asm.org/cgi/reprint/64/1/258


http://web.archive.org/web/20061022185933/www.marineland.com/science/dr_tim/drtims_articles.asp

 

[brianp]

? Somewhere I read nitrate produces hydrogen ions ?
If that statement is true won't the hydrogen ions acidfy the aqaurium, by bonding to the buffering compounds?

on another point a PH of 5.5 or lower the bacteria needed to convert AMM to Nitites begans to die...so your AMM levels should have shown something?

the lower PH will protect the fish by keping the AMM less toxic. When your PH rises , your present AMM levels become toxic..

Any signs of hole in the head or lateral line erosion? stunting?

I'm not an expert in this area, but NITRATE is NO3-. It has no H+ to contribute. Yes, anything that can dissociate to liberate an H+ will cause the pH to drop in the absence of effective buffering. If the H+ binds to a buffer, it will have no effect upon pH. The role of a buffer in any system (aquarium, blood, etc.) is to absorb or donate H+ as required to prevent a pH change..up or down.

If I'm not mistaken, nitrite is converted to nitrate in the following manner: NO2- + H2O = NO3- + 2H+

But these 2H+ then react with a single oxygen atom inside the bacterium to form H2O...so they are not released.

I could be wrong, but I don't see how nitrate can cause the pH to drop.