What causes pH to rise?

[stillnzcookie]

Due to unforeseen circumstances, we haven't always been quite as regular with our water changes over the last few months :oops: . Usually we do weekly water changes, and we ALWAYS test pH levels, as we have soft water, and have had problems in the past with pH dropping. Now that we have coral rock in the filter, the pH is usually between 6.8 and 7.0, which our fish all seem perfectly happy in (panda cories, harlequin rasboras and dwarf neon rainbowfish). We test pH both before and after each water change.

However, I have noticed that, when we don't do a water change for a couple of weeks, the pH always seems to go up quite dramatically. Today it was 7.6 when I tested beforehand, and is now back to 7.4. Our fish seem to cope ok with this - the only change I have noticed is that their colours dull slightly - but I am aware it is not ideal for them to have such big swings in pH. Tests for ammonia, nitrite and nitrate are all always fine.

I can understand why pH can drop over time, but can anyone tell me what could be causing it to rise? I know the solution is to keep up with the weekly water changes, but I'm curious as to what is causing it.

Thanks!

[David R]

and have had problems in the past with pH dropping. Now that we have coral rock in the filter, the pH is usually between 6.8 and 7.0

There's your answer. TBH I'd just keep up with water changes and stop checking the pH....

:lol:

[Ira]

And you could probably take a bit of the coral rock out because it's obviously increasing the PH faster than other factors are dropping it.

[Charlie]

if the Ph is changing that fast your fish would be dead... I think your test kit may be out?

Its called a Ph crash and normally results in a mass wipe out.

[stillnzcookie]

Thanks for the replies

And you could probably take a bit of the coral rock out because it's obviously increasing the PH faster than other factors are dropping it.

Yes, that seemed logical to me, except that we were told we would have to gradually replace/add more over time, as it would lose its buffering effect. It took us about three months of slowly adding more and more to the filter until it stopped the pH dropping, and that was over 18 months ago now, so if anything, I would have expected the pH to be gradually dropping, not rising by now.

I will take out a bit and see what happens, but I'm nervous about doing it in case I remove too much and we start having pH crashes again (this has been the cause of almost all our fish deaths )

Actually, I didn't realise coral rock would make pH rise - I thought it just acted as a buffer to keep it more stable?

[David R]

if the Ph is changing that fast your fish would be dead...Its called a Ph crash and normally results in a mass wipe out.

What? pH rising from 7.0 to 7.6 over a "couple of weeks" is called a crash and would kill all your fish?????

oh, you said Ph, not pH, you must be talking about telecoms XT network or something. Glad I stuck with vodafone, I'd hate for my Ph to crash and kill all my fish. :-?

[Ira]

if the Ph is changing that fast your fish would be dead... I think your test kit may be out?

Its called a Ph crash and normally results in a mass wipe out.

That's not a ph crash. Even over a couple days rather than weeks the fish would probably be ok.

[alanmin4304]

I agree. The difference between pH 7.0 AND pH 7.6 is not great over two weeks as the scale is logarithmic and it is at the lower end.

[livingart]

What? pH rising from 7.0 to 7.6 over a "couple of weeks" is called a crash and would kill all your fish?????

some things are a slow crash waiting to happen

[stillnzcookie]

Ok, now I'm really confused...

pH after water change last night was 7.4. Retested at lunchtime today and it was down to 6.8. I boiled our driftwood last night, as it was covered in algae, so I THINK this may have caused it? Am I correct in thinking that driftwood softens water, which can cause pH to drop?

Fortunately, the fish seem very happy - they are more active and have their vibrant colours back again - but I'm nervous that there might be a disaster waiting to happen.

So what should I do? Should I add more coral rock? (given that yesterday I was on the verge of removing some of it? :roll: ). Will adding more stabilise pH or just cause it to rise?

Also, does temperature influence pH and, if so, how?

For us, this has been the most frustrating and upsetting thing about keeping fish. Fluctuating pH levels are the bane of our lives - just when we think we've got it sorted, everything goes haywire again :evil:

Just to make life more complicated - I know that stable pH is the first thing we should be aiming for, as I have been told many times that fish can live happily in quite a range of pH, as long as it is stable, but our fish really seem happier when the pH is just below 7.0. When it sits at 6.6-6.8, I notice that the fish are more active and their colours are more vibrant. If only we could keep it there all the time...

[Ira]

Am I correct in thinking that driftwood softens water, which can cause pH to drop?

Very slightly. The best thing you can do to stabilise your PH? Stop testing for it. The reason hypochondriacs are always sick isn't because they keep getting ill. You're probably causing half your problems and stressing for no reason.

[David R]

As Ira said, keep up with regular consistant water changed, leave the tank as-is and don't worry about it unless there is a reason to.

[Southerrrngirrl]

Very slightly. The best thing you can do to stabilise your PH? Stop testing for it. The reason hypochondriacs are always sick isn't because they keep getting ill. You're probably causing half your problems and stressing for no reason.

I totally agree with this.

Ok, now I'm really confused...

pH after water change last night was 7.4. Retested at lunchtime today and it was down to 6.8. I boiled our driftwood last night, as it was covered in algae, so I THINK this may have caused it? Am I correct in thinking that driftwood softens water, which can cause pH to drop?

Did you test the pH of the water BEFORE you put it in the tank?

[David R]

Another thing to try would be doing more frequent smaller water changes instead of one larger one, if there is a big difference between your tap water and tank water.

[stillnzcookie]

The best thing you can do to stabilise your PH? Stop testing for it. The reason hypochondriacs are always sick isn't because they keep getting ill. You're probably causing half your problems and stressing for no reason.

Point taken, but most of our fish deaths have been caused by pH problems (and a killer harlequin, but that's a whole different story...). It's not like we're actively trying to adjust pH all the time - we test for it, do regular water changes and have been using coral rock to try to stabilise it, but that is all we've done over the last year or so. When we first started having problems, we got sucked in by all the people trying to sell us stuff to alter pH, but we quickly realised that just created far bigger problems (and far more mortalities), so we take a hands-off approach now, which has been working fine until this week.

Did you test the pH of the water BEFORE you put it in the tank?

Yes, the tap water was 7.4 on the night I put it in. Our tap water is very soft and, as a result, the pH varies considerably - I have measured it from 6.0 - 7.8 (and our test doesn't go beyond that). I have been told that the coral rock acts as a buffer, so the pH in the tank shouldn't be too affected by the pH of the tap water anyway.

Another thing to try would be doing more frequent smaller water changes instead of one larger one, if there is a big difference between your tap water and tank water.

We do smaller changes than when we first got the tank - about 20-30% per week - but, as above, it doesn't usually seem to cause problems anyway.

SO, I've chucked a bit more coral rock in the tank, as the pH was still falling, so I'm hoping that will stabilise it a bit.

Thanks for all the replies, but I'd still love an answer to the original question - what could cause pH to rise over time? It's NOT because I'm trying to fix a problem, I'm just curious as to how it can happen! And alongside that - does coral rock cause a rise in pH, or does it just act as a buffer to stabilise pH?

Thanks!

[Stella]

How do you know pH swings CAUSED the death of the fish?

Like others said, stop stressing.

Get a 44 gallon drum and put the coral in there, not in the tank. Each time you do a watch change use water from the drum and then refill it so it is primed for the next water change.

Better yet, working WITH nature is easier than against, get fish that like soft slightly-alkaline water.

[David R]

Thanks for all the replies, but I'd still love an answer to the original question - what could cause pH to rise over time?

As I said in my first post, the coral would have caused the pH to rise, thats how it stops the pH dropping, and when you left the water change longer than usual it just kept rising.