Sudden pH drop

[dalto]

How did you calculate the 64x lower on the pH scale?

I am not sure how he calculated 64x (I am too lazy to do the math myself right now) but the pH scale is logarithmic. So moving an integer in either direction results in a 10x increase, 2 would be 100x. So if you went from 7.5 to 9.5 your water would be 100x more base.

 

[Caliban07]

How did you calculate the 64x lower on the pH scale?
The African cichlids are resilient tough fish, I acted quickly in bringing up the pH and right away is was like they revived, they were all in sad shape with their gills practically coming out in a rapid breathing motion some laying on the bottom.
I'm not one to obsess over water parameters, this one has me going though.
Checked the local water supplier's web site as you suggested and nothing current, all readings are from 2013 with no alerts.

A logarithm is the power to which a number must be raised in order to get some other number. For example, the base ten logarithm of 100 is 2, because ten raised to the power of two is 100:

log 100 = 2

because

10^2 = 100

This is an example of a base-ten logarithm. We call it a base ten logarithm because ten is the number that is raised to a power. The base unit is the number being raised to a power.

Mathematically, pH is the negative logarithm of the activity of the (solvated) hydronium ion, more often expressed as the measure of the hydronium ion concentration.

pH = - log[concentration of H+ ions] OR this can be written as pH = -log[H3O+]

So, if a solution has a pH of 3, the concentration of H+ ions = .001 If a solution has a pH of 6, the concentration of H+ ions is .000001

10^-3 = 0.001

And

10^-6 = 0.000001

How many times more 'acidic' is the pH 3 solution? 0.001/0.000001 = 1000

So 10^-7.8 = 0.000000015848132

And

10^-6 = 0.000001

So finally

0.000001/0.000000015848132

= 63.0989132

So actually it's a little over 63x not quite 64 like I said.

Hope this helps.

Glad your fish are better



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[Noviceafter2yea]

Peace out, you guys are way over my head with this stuff and I consider myself fairly intelligent!

 

[gilpi]

Peace out, you guys are way over my head with this stuff and I consider myself fairly intelligent!

I'm just like you or else I wouldn't be asking questions, hang around!

 

[Noviceafter2yea]

I'm just like you or else I wouldn't be asking questions, hang around!

I will follow, just not following. I always like to read more information. Can't participate is all.

 

[Delapool]

If the fish have been thriving and growing at a good rate, water is always a stable 7.8 and after a big water change the pH dropped to around 6.0, I would say that the pH drop put them into shock, as to why the drop , I'm not sure yet, that remains the mystery as I haven't checked the KH, last night the tap water's pH was down again, I'll check the KH tonight.
As for TDS if you're referring to poor tank maintenance, I probably over maintain, with massive water changes weekly or bi weekly.
TDS in the tap water? I wouldn't know since I don't have a tester.

Thanks for the post back, it wasn't concern on poor maintenance but if the drop was purely ph related or if the ph was highlighting a TDS drop or something else going on.

 

[gilpi]

Thanks for the post back, it wasn't concern on poor maintenance but if the drop was purely ph related or if the ph was highlighting a TDS drop or something else going on.

No problem, I appreciate any comment. Im really not too familiar with TDS and didn't know that a TDS drop would also cause pH to drop

 

[DragonFish71]

I appreciate the advice but far from old tank syndrome here!
Old tank syndrome refers to a tank that has being through very low maintenance over a long period of time.
I actually get beat up in this forum for promoting lots of big water changes, my tanks get a 50% to 80% water change weekly sometimes twice a week and filters get serviced regularly gravel gets a good vacuum as well.

The pH lowered overnight from close to 8.0 to almost 6.0 and happened right after a water change, first time this happens in years using the same water source.

Again, I appreciate your help and everyone else's. Just trying to figure it all out, had I not checked the tanks this morning I think I would have had at least one whole tank wiped out.


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My tanks that this happened to get the same water change as yours do, 50%-80% weekly due to the heavy stocking. "Old tank syndrome" isn't about poorly maintained tanks if you read more than one or two articles, I found quite a few that discussed tanks like mine, set up for years, regular good maintenance, that do not buffer and drop like a rock.

 

[gilpi]

KH, GH and pH readings tonight....

Tap water, aerated and dechlorinated for a day...
KH 53
GH 125
PH 6.8

From the Mbuna tank after adding 3 teaspoons of baking soda and 3 teaspoons of Epsom salt slowly through out the day yesterday...
KH 71
GH 300
PH 8.0

Any thoughts?

 

[Noviceafter2yea]

KH, GH and pH readings tonight....

Tap water, aerated and dechlorinated for a day...
KH 53
GH 125
PH 6.8

From the Mbuna tank after adding 3 teaspoons of baking soda and 3 teaspoons of Epsom salt slowly through out the day yesterday...
KH 71
GH 300
PH 8.0

Any thoughts?

Are you using something to clean your test tubes that may be off? Well, I guess if you were, then readings would not improve. Something to consider maybe anyway...on some remote chance


Edit*** just noticed you were comparing tap water to treated tank water. In any case, it's a good thing the tank is evening out, right?

 

[gilpi]

This is after the fact readings, I think the tap water must have had even lower reading a few days ago when I did water changes.
I would still think this is pretty low?
In the past pH has always been 7.8 to 8.0 and never had a pH crash.

 

[PNWaquarist]

Good call on the baking soda. That's exactly what I would've done. Calcium carbonate is no good for emergencies, as it's only slightly soluble and will take forever to raise the tank's pH.

Didn't you guys have a really heavy rainfall a week or two ago? That may have changed the pH of the storage tanks at municipality's water facilities. I'd check the pH of the tap water weekly from now on.

 

[enrgizerbunny]

Sounds like somebody dropped a jug of acid in at the ole water treatment facility and didn't want to do the paper work.

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[Delapool]

KH, GH and pH readings tonight....

Tap water, aerated and dechlorinated for a day...
KH 53
GH 125
PH 6.8

From the Mbuna tank after adding 3 teaspoons of baking soda and 3 teaspoons of Epsom salt slowly through out the day yesterday...
KH 71
GH 300
PH 8.0

Any thoughts?

I would of thought that kh in tap would of buffered to 7? Does kh have to drop towards 0 before ph will go below 7 - does anyone know/tested??

 

[dalto]

I would of thought that kh in tap would of buffered to 7? Does kh have to drop towards 0 before ph will go below 7 - does anyone know/tested??

No, KH measures how well buffered the water is. Think of it as a measure of how hard pH is to change if that makes it easier. KH does not have to be 0 to get acidic water.

 

[gilpi]

Good call on the baking soda. That's exactly what I would've done. Calcium carbonate is no good for emergencies, as it's only slightly soluble and will take forever to raise the tank's pH.

Didn't you guys have a really heavy rainfall a week or two ago? That may have changed the pH of the storage tanks at municipality's water facilities. I'd check the pH of the tap water weekly from now on.

We've had some rain but not that much overall.
I occasionally checked pH but never the KH or GH. I'm thinking the low readings were not enough to buffer the water therefore the drop?



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[PNWaquarist]

I would of thought that kh in tap would of buffered to 7? Does kh have to drop towards 0 before ph will go below 7 - does anyone know/tested??

KH is a measure of the concentration of dissolved carbon dioxide and bicarbonate ion (the buffer). Higher KH means more buffering capacity (will resist a greater change in pH).

 

[PNWaquarist]

We've had some rain but not that much overall.
I occasionally checked pH but never the KH or GH. I'm thinking the low readings were not enough to buffer the water therefore the drop?

My KH is a good 10 ppm lower than yours and I don't have problems with pH fluctuations. Mine's always in the 7.3-7.4 range.

In theory, you and I both have low-ish KH and not a tremendous amount of buffering capacity, but that doesn't mean a whole lot in practice. If your tap water pH has been very stable for many years, the pH crash has to do with your water treatment facility and not the buffering capacity of your water.

 

[Delapool]

KH is a measure of the concentration of the buffer. Higher KH means more buffering capacity (will resist a greater change in pH).

Well for me a kh of 3 or 54 will stay ph around 7.3. The only time it has gone below 7 is when kh was 0 basically.

I would of thought a ph below 7 of acid conditions will keep chewing through the kh and coming back up to 7? Once kh has been used up, then ph can drop into the 6'ish values?

 

[PNWaquarist]

Well for me a kh of 3 or 54 will stay ph around 7.3. The only time it has gone below 7 is when kh was 0 basically.

I would of thought a ph below 7 of acid conditions will keep chewing through the kh and coming back up to 7? Once kh has been used up, then ph can drop into the 6'ish values?

When you're at a KH of 0, you have no CO2/bicarbonate buffer. So the addition of an acid will easily lower your pH, and the addition of a base will easily raise your pH.

A KH of 0 has no relationship to a neutral pH of 7.0. KH is a measurement of your tank water's resistance to pH change, and that's it.

If you want to see the relationship between buffer concentration and pH in mathematical form, you can check out the Henderson-Hasselbalch equation.