Ph or alkalinity

[Cory]

Is it high ph or high alkalinity that is likely to harm or kill an animal?

If i raise alkalinity without changing the ph at all, this would or wouldn't be harmful?

 

[Randy Holmes-Farley Verified Community Expert]

Depends on the creature, and the levels you are talking about, as well as what else is going on, like nutrient levels.

Most reef tanks do not get high enough pH to hurt anything without rapidly dosing high pH additives.

 

[Randy Holmes-Farley Verified Community Expert]

How high are you thinking of raising alkalinity?

 

[Cory]

I wasnt going to raise it, im just interested in knowing which is more harmful. Because youve said before that you want to limit the rise of ph. Thus i was wondering if its rapid raises in ph or alkalinity, or some other factor that harms tank inhabitants. Because we can add alk supplemts that dont effect ph barely at all like sodium bicarbonate. While hyrated lime raised it lots and seems to be a bad idea and must be dripped. Thus it seems ph is the negative factor not alklainity. True?

 

[redfishbluefish]

Short of adding something to your tank that you shouldn't be adding, I have never heard of the daily changes in pH being an issue. However, large changes in alkalinity can be problematic. The accepted rule of thumb is to not change alkalinity more than 1 dkH per day.

 

[Randy Holmes-Farley Verified Community Expert]

I've not really seen any data that could be used to compare the relative problems caused by alkalinity and pH issues. I'm not even sure what one might say is an "equivalent" change in two things that are measured so differently.

For pH, I really do not think that most creatures suffer from daily pH changes, but rather from the extreme ends of the changes. So a pH varying from 8.1 to 8.4 may be better than a constant 7.7.

I do not know that the same can be said about alkalinity.

But overall, it will depend strongly on the organisms you are focusing on.

 

[Cory]

I've not really seen any data that could be used to compare the relative problems caused by alkalinity and pH issues. I'm not even sure what one might say is an "equivalent" change in two things that are measured so differently.

For pH, I really do not think that most creatures suffer from daily pH changes, but rather from the extreme ends of the changes. So a pH varying from 8.1 to 8.4 may be better than a constant 7.7.

I do not know that the same can be said about alkalinity.

But overall, it will depend strongly on the organisms you are focusing on.

I see. My question now that ive pinned it down is more related to "when you add it all at once". Whats worse, the rapid change in ph, or the rapid change in alkalinity? One time i put a small uncured chunk of cement in my tank thinking it would maintain calcium and alk. Well it killed everthing. Some fish had developed a skin rash. And had red veins in them, like my yellow tang. This was 8 years ago. So that where part of my curiosity comes from.

It seems if you raise the ph, which hurts things, like for example put your hand in limewater and the high ph will burn your skin. But high alkalinity to your hand, wouldnt do the same, right? So it seems ph is worse rather than alkalinity. Its like ph speeds alkalinities effect up in general.

What organisms are more sensitive to ph, rather than alk?

 

[Randy Holmes-Farley Verified Community Expert]

Well, still hard to answer.

As far as I know, only SPS are sensitive to rapid changes in alkalinity, but I am not sure if that only applies to sustained changes.

For example an SPS in a ULNS tank that jumped from 7 dKH to 9 dKH and stayed there might have trouble with burnt tips. I'm not sure that same thing would apply if there was a daily cycle from 7 dKH to 9 dKH.

As to pH, I'm not sure that any of the organisms we keep "suffer" from pH when in the range of 7.8 to 8.5, no matter how fast it changes, but I've not seen any careful study of that effect. I do think that many will grow faster at lower or higher pH, depending on what type of organism they are and what else might be limiting their growth (hard corals maybe faster at higher pH, macroalgae maybe faster at lower pH).

 

[Randy Holmes-Farley Verified Community Expert]

It seems if you raise the ph, which hurts things, like for example put your hand in limewater and the high ph will burn your skin. But high alkalinity to your hand, wouldnt do the same, right? So it seems ph is worse rather than alkalinity. Its like ph speeds alkalinities effect up in general.

Limewater at pH 12.5 has much more than 10,ooo times as much OH- as does seawater, and it is the OH- that does the damage to your hand (hydrolyzing fats in membranes and such to soaps). If you put your hand in water with 10,000 times as much alkalinity (not possible, but assume for the idea experiment), your hand likely would not be happy either, but maybe not as bad as in high pH.

That's why I was saying it is hard to compare what might be "equivalent" changes.

 

[McMullen]

All vertebrates are sensitive to pH. I won't make that assumption with inverts but would assume all high level inverts are also sensitive. There is a narrow range with which verts can tolerate/survive. There are far too many variables to discuss from a biochem perspective as to what happens inside cells. Organisms can compensate to slow changes over hours, days, and weeks but if pH is not eventually corrected back to "normal," death will occur. Organisms cannot tolerate wide changes rapidly without immediate correction, even then if too extreme death will occur. Again, the why is extremely complex and involves hundreds if not thousands of biochemical processes including cells ability to oxygenate. So in my mind the question should be, "How can I always maintain optimal pH and alkalinity for my reef inhabitants?"

 

[Cory]

Limewater at pH 12.5 has much more than 10,ooo times as much OH- as does seawater, and it is the OH- that does the damage to your hand (hydrolyzing fats in membranes and such to soaps). If you put your hand in water with 10,000 times as much alkalinity (not possible, but assume for the idea experiment), your hand likely would not be happy either, but maybe not as bad as in high pH.

That's why I was saying it is hard to compare what might be "equivalent" changes.

That makes sense. What is happening when fats gets hydrolized? Is just stealing electrons or something?

When a tank is in normal limits 7.8-8.5ph, a bump from 7.8 to 8.5ph may be ok, right. But a bump from 8.5 to 9ph would not, right. Whats the reason for that? Im guessing they are not adapted to that ph. Or its a time factor and concentration amount.

I think ph is slightly worse than alkalinity based on what you said.

Is there some sort of common denominator that is causing ph? Trying to pinpoint something here.

 

[McMullen]

Are you wanting to pinpoint with coral or fish. They will react and tolerate different amt and levels and swings and etc, etc.
Whatever it is, try researching biochemical processes of the organism in question. Remember this an extremely complex subject and searching for answers with the "tank" in mind will get you nowhere. You've got to narrow your focus. Also, remember we have swings in pH and elements in our tanks that the ocean does not have. From the perspective of an individual organism, swings may be tolerated as long as they are small or over long periods of time, but they are not optimal for pristine health.
I don't understand the question about "common denominator that is causing pH." Are you asking what is pH? What effects pH? How important is proper pH?

 

[Randy Holmes-Farley Verified Community Expert]

That makes sense. What is happening when fats gets hydrolized? Is just stealing electrons or something?

When a tank is in normal limits 7.8-8.5ph, a bump from 7.8 to 8.5ph may be ok, right. But a bump from 8.5 to 9ph would not, right. Whats the reason for that? Im guessing they are not adapted to that ph. Or its a time factor and concentration amount.

I think ph is slightly worse than alkalinity based on what you said.

Is there some sort of common denominator that is causing ph? Trying to pinpoint something here.

The mechanism of triglyceride hydrolysis by hydroxide is detailed here:

https://en.m.wikipedia.org/wiki/Saponification

One reason a bump to pH 9 is not OK is that it is likely outside the range that many cells exposed to that pH may be unable to maintain their normal ion transport across membranes (which often involves H+) when the H+ levels are so far from their normal concentration.

Besides that, magneisum hydroxide and calcium carbonate will precipitate.