Buffering Kh?

[JohnRossDele]

hi all,
how do u buffer the KH to 4 degrees and leaving the PH at 7.0?

 

[Bobtastic]

I think it would depend on the level of the KH. You could use a manufactured pH Buffer. I think they are designed to buffer your water at the selected pH level. If you didn't want to use a manufactured buffer you could use Crushed Coral, but they'll be a lot harder to control so such a exact level.

 

[JohnRossDele]

I think it would depend on the level of the KH. You could use a manufactured pH Buffer. I think they are designed to buffer your water at the selected pH level. If you didn't want to use a manufactured buffer you could use Crushed Coral, but they'll be a lot harder to control so such a exact level.

will the kh go to 4 if i used this and ph 7 or

 

[Bobtastic]

TBH I wouldn't like to say... I think that with the pH Buffer product you select the required pH (in your case pH7) and then you add the approriate amount of powder for the volume of your tank and that adds GH/KH to the water and stablises your water at the required pH.

The problem with this is that you are adding/disolving more things into the tank water which will increase the osmotic pressure and stress on the fish.

Why do you need to increase the KH and not affect the pH? Is there a specific need?

 

[JohnRossDele]

TBH I wouldn't like to say... I think that with the pH Buffer product you select the required pH (in your case pH7) and then you add the approriate amount of powder for the volume of your tank and that adds GH/KH to the water and stablises your water at the required pH.

The problem with this is that you are adding/disolving more things into the tank water which will increase the osmotic pressure and stress on the fish.

Why do you need to increase the KH and not affect the pH? Is there a specific need?

for breeding kribs i need both male and female fry

 

[nmonks]

You never, ever alter pH without considering KH. It's one of the most common "beginner" mistakes in water chemistry to just add pH buffers and hope for the best. This is why some magazines, for example TFH, simply don't recommend changing water chemistry at all -- far too many aquarists don't understand what's going on, and in the process, cause major problems.

Carbonate hardness is what "holds" the pH at a certain value. When carbonate hardness (measured in degrees KH) is low, the background acidification in ALL tanks proceeds very quickly. Freshwater tanks become acidic after water changes because of the decay of organic material coupled with increasing amounts of nitrate (which becomes nitric acid in water) reduces the pH. This is why soft water tanks are run at a low stocking density.

If you want a neutral pH, and you want that pH to be stable from week to week, you need a moderate level of carbonate hardness. There's no fixed "amount" because it will vary on other factors: whether you're adding CO2, how much bogwood there is, what the nitrate level is, how many fish there are, whether the tank is clean or filled with organic muck, and so on. This is why you have to be careful. But if you have a moderate carbonate hardness, something like 3-4 degrees KH, then the use of a pH buffer should work safely.

If the carbonate hardness is lower than 3 degrees KH, there's a good chance pH will drop between water changes. This would be very harmful for a variety of reasons. Acidosis would be one issue, meaning the fish themselves would be stressed, but a more serious threat is the reduction in biological filtration. Filter bacteria prefer a basic pH (7.5 upwards, ideally) and essentially stop working below pH 6. So the more pH goes down -- the more acidic water becomes -- the less effective your biological filter. This in turn means that as the pH drops, ammonia and nitrite problems become more likely.

If the carbonate hardness is higher than, say, 5 degrees dH, it can be very difficult to use pH buffers to create a steadily neutral or acidic pH. You need to use a lot of the buffer to neutralise the alkalinity in each bucket of water, and anything calcareous in the tank will counteract the acid buffer over time, causing the pH to rise again.

In short, it's important to remember the single most important rule of water chemistry: pH itself rarely matters, but pH stability is critically important.

Cheers, Neale

Why do you need to increase the KH and not affect the pH? Is there a specific need?

 

[Bobtastic]

^^^ What he said!!! ^^^

Hehehe

 

[aaronnorth]

In short, it's important to remember the single most important rule of water chemistry: pH itself rarely matters, but pH stability is critically important.

what do you call stable? i take it you are talking about fluctuations in pH so a what ldegree of change would you say becomes critical to fish?

 

[nmonks]

The pH scale is an exponential one. So while a shift from 7 to 7.1 isn't very great, a shift from 7 to 8 is huge.

One or two "tenths" (7 to 7.1, or 7 to 7.2) isn't serious and most fish will handle that just fine. But if you find your aquarium shifts from 7 to 8, or 7 to 6, then that's very serious indeed.

Cheers, Neale

 

[aaronnorth]

The pH scale is an exponential one. So while a shift from 7 to 7.1 isn't very great, a shift from 7 to 8 is huge.

One or two "tenths" (7 to 7.1, or 7 to 7.2) isn't serious and most fish will handle that just fine. But if you find your aquarium shifts from 7 to 8, or 7 to 6, then that's very serious indeed.

Cheers, Neale

mine falls and rises by 1 unit per day (7.5 > 6.5, then at night 6.5>7.5) because of CO2 injection. It isn't a sudden change, but it is when i do a 50% water change as it comes out at pH8 from my tap, so i dont find changes in pH serious at all. Bignose posted some inormation that fish can change their internal pH by 4units quite quickly, and that a change in hardness is a more serious issue over pH change,

http/www.fishforums.net/index.php?s=&amp...t&p=2415653

http/www.fishforums.net/index.php?s=&amp...t&p=1692388

thanks, Aaron

 

[nmonks]

I don't agree with Bignose at all on this one, I'm afraid.

I agree that some fish can and will tolerate big water chemistry changes; the brackish water fish I write about for example will do so each time the tide changes. Likewise freshwater fish adapted to marginal habitats, such as killifish, need to be able to adjust to sudden changes in environmental conditions.

But most other habitats* are extremely stable: Rift Valley lakes, major rivers, coral reefs for example. Fish from such places won't be experiencing significant pH changes across a daily cycle. I find it inconceivable such fish could adjust to 4 units -- pH 5 to pH 9 -- within an hour!

Also, the idea rainwater dramatically changes pH isn't as compelling as its sounds. Except perhaps for a very small pond, which wouldn't have any fish anyway, the amount of rainwater added in an average shower isn't going to be that great, perhaps a few percent of the volume of whatever the rain was falling into. That isn't going to change the pH much unless the water is very, very soft. It will have virtually zero impact on the sea, little more on a big lake like Lake Malawi, and hardly anything on a major river like the Nile or Amazon. Such bodies of water receive vastly greater inputs of water from other places, and depending on the ambient geology, pH is going to be controlled by things like dissolved carbonate salts.

A quick Google search turned up some results for the Colorado River, which showed daily change before and after floods; as you can see, the pH isn't that great in either case, at the most extreme, going from pH 8 to 8.25.

Cheers, Neale

*Some artificial habitats such as ponds probably experience significant variation in water chemistry across the day, but that's a different issue altogether.

 

[CKutz]

i'm hijacking this thread while it's got attention. Sorry!!

I brought my 10 gal tank back from school for the summer, I tried to preserve the bacteria by keeping the media in a bag of tank water. Something didn't work out right...since may 6th when i moved back my tank has had a ph of 6 or less. the ammonia builds up, but some amount is apparently being broken down to nitrites as nitrites do accumulate if given time. even nitrates develop..but it shouldn't be like this this bad yet. I mean i just changed almost all the water yesterday, maybe 80%. and my ph is back down to 6 (or less) already, there is .5-1 ppm ammonia, and .25-.5 nitrites, and 5 ppm nitrates.
i also changed the water in my 30 gal. it's ph is somewhere between 6.6 and 7.2...the api test is so tough to tell the differences..

additionally, once i tested my tap ph, after letting it set out for 24 hrs. it read about 7.
so my guess is the ammonia is driving down the ph, which sets the bacteria dormant mostly.

my 30 gal was a used tank, came with rocks..one i believe was once live rock..it's very holy, has a clam shell embedded in it. with the whole rock in my tank the ph was like 8 something..so i took it out and it stayed around 7 till my filter broke (now i'm having cycling issues with the 30, but it's working itself out).
So i figured instead of crushed coral maybe i could add a chunk of this to each tanks filter and help raise the KH so when i do a waterchange it stays closer to tap levels. it seems to have worked in my 30 gal, but not my 10. the ph is still really low. should i try a bigger piece?

what the heck do i have to do to get my 10 gal back in order..i tried keeping up with it for awhile but the ph always dropped..i finally gave up. and with the same decor and stuff the tank used to have a 7 or 7.2 ph

if anyone reads all that...thank you very much for your time haha. i'm just getting really frustrated with it.

 

[nmonks]

Yep, that's hijacking a thread all right...

In any case, there's a bunch of things going on. For a start, some ammonia may be present in the tap water you add to the aquarium. Check. Do also check whether chloramine is used by your water supplier; if it is, and you don't use a dechlorinator that treats chloramine as well, you'll get elevated levels of ammonia.

Secondly, as pH drops, biological filtration proceeds more slowly, and at around pH 6, it stops entirely. You need to stabilise pH if you want steady biological filtration.

Thirdly, some water supply is "unstable". Specifically, the mix of chemicals used to create potable water changes as it reacts with air, and you get a pH that changes as well as seeming changes in water chemistry. I don't really understand why this happens, but for whatever reason, I mostly (always, I think) hear about this from aquarists in the US, so seems to be something to do with how American water companies "package" drinking water or well water.

Do always remember NOT to use water from a domestic water softener. Though there's some debate about this, this type of water softener work primarily by adding salt as it replaces carbonate hardness, producing something very different to what freshwater fish actually want.

It's often best to harden water even if you aren't keeping specifically hard water fish species. Most tropical fish will do perfectly well in moderately hard water with a slightly basic pH; say, 10 degrees dH, 3-4 degrees KH, and pH 7.5. That would be acceptable for most barbs, most tetras, virtually all catfish, and almost all cichlids other than Rift Valley species. If your water is very soft or the pH isn't stable, then hardening the water (particularly in terms of carbonate hardness) will provide a quick fix. Obviously fish that prefer hard water, like livebearers, goldfish and rainbowfish, will be much happier with hard water anyway, so it's a good idea to do that when keeping them.

There's a Rift Valley cichlid salt mix on my web page; used at about 50% the dosage recommended there, you should be able to create a cheap, stable kind of water that works well for most fish.

Cheers, Neale

 

[Dave Spencer]

The pH scale is an exponential one. So while a shift from 7 to 7.1 isn't very great, a shift from 7 to 8 is huge.

One or two "tenths" (7 to 7.1, or 7 to 7.2) isn't serious and most fish will handle that just fine. But if you find your aquarium shifts from 7 to 8, or 7 to 6, then that's very serious indeed.

Cheers, Neale

I run very soft water (from the tap) planted tanks with CO2, wood and ferts all driving the pH down. I have a lot of surface disturbance too for a high CO2, high O2 environment. When the CO2 switches off overnight, the surface disturbance outgasses the CO2 over the lights off period to a point where 30ppm CO2 has become ambient, resulting in a daily pH fluctuation of around 1 pH. My fish have never shown any problems with this.

Dave.

 

[thecommonnate]

You never, ever alter pH without considering KH. It's one of the most common "beginner" mistakes in water chemistry to just add pH buffers and hope for the best. This is why some magazines, for example TFH, simply don't recommend changing water chemistry at all -- far too many aquarists don't understand what's going on, and in the process, cause major problems.

Carbonate hardness is what "holds" the pH at a certain value. When carbonate hardness (measured in degrees KH) is low, the background acidification in ALL tanks proceeds very quickly. Freshwater tanks become acidic after water changes because of the decay of organic material coupled with increasing amounts of nitrate (which becomes nitric acid in water) reduces the pH. This is why soft water tanks are run at a low stocking density.

If you want a neutral pH, and you want that pH to be stable from week to week, you need a moderate level of carbonate hardness. There's no fixed "amount" because it will vary on other factors: whether you're adding CO2, how much bogwood there is, what the nitrate level is, how many fish there are, whether the tank is clean or filled with organic muck, and so on. This is why you have to be careful. But if you have a moderate carbonate hardness, something like 3-4 degrees KH, then the use of a pH buffer should work safely.

If the carbonate hardness is lower than 3 degrees KH, there's a good chance pH will drop between water changes. This would be very harmful for a variety of reasons. Acidosis would be one issue, meaning the fish themselves would be stressed, but a more serious threat is the reduction in biological filtration. Filter bacteria prefer a basic pH (7.5 upwards, ideally) and essentially stop working below pH 6. So the more pH goes down -- the more acidic water becomes -- the less effective your biological filter. This in turn means that as the pH drops, ammonia and nitrite problems become more likely.

If the carbonate hardness is higher than, say, 5 degrees dH, it can be very difficult to use pH buffers to create a steadily neutral or acidic pH. You need to use a lot of the buffer to neutralise the alkalinity in each bucket of water, and anything calcareous in the tank will counteract the acid buffer over time, causing the pH to rise again.

In short, it's important to remember the single most important rule of water chemistry: pH itself rarely matters, but pH stability is critically important.

Cheers, Neale

Why do you need to increase the KH and not affect the pH? Is there a specific need?

If Nitrate becomes nitric acid in water, wouldn't this raise the pH, and not lower it? I say this because what you say relies on Nitrate acting as a base in the Bronstead-Lowry theory, as Nitrate, NO3-, is accepting a hydrogen ion to become nitric acid HNO3.