I still don't understand pH

[KatNor21]

My pH in every tank I have is low and I don't know how to raise it or if I need to. Seems most fish like a pH of 7ish, but my tanks are always around 6. My 30 gallon might even be below 6, the test strip is really yellow. I have honey gourami and neon tetras and loaches in that tank, so I don't know if that's OK or not. Seems neons would want it higher. I have plant substrate in there that lowers pH so that's probably why, but I want to support the plants as well.

I asked someone at Aquarium Co-op how to raise the pH and they said add crushed coral. But that just makes my water hard and it's already hard enough. My 30 gallon GH is about 75-150ppm. I don't want to raise it any higher for the fish's sake.

I also have a 5.5 gallon with a pH of 6.5 and GH of 150ppm. That tank has shrimp who may prefer a higher pH as well. What am I missing here? Am I worrying too much about it or should I be raising it? How would I go about doing that?

 

[Byron]

First off, the pH is part of the GH and KH, and depending upon the latter two factors, the pH is going to settle out at "x" level. The GH has the greatest direct impact on fish, from the perspective of soft water species and hard water species (to generalize). Soft water usually has a pH on the acidic side, and hard water usually has a pH on the basic (above 7.0) side. We can forget the "exceptions" for the moment to avoid more confusion. So fish that live in soft water will almost always be healthier with a pH below 7, and vice versa.

To say most fish like a pH of 7 is very inaccurate, and I do wish people on the internet and in stores (who do not obviously understand any of this) would stop spreading this fallacy. First off, "pure" water with a neutral (7.0) pH does not exist in any habitat. Water leaves the clouds as pure water, but by the time it reaches the ground it is not; water is one of the most powerful natural solvents on this planet, and it readily assimilates substances like minerals (making it harder) or organics (making it softer), and the pH corresponds.

Fish prefer (and thus require) water that is on the soft side, or water that is on the hard side. Some species do well in the middle, either slightly soft/acidic or slightly hard/basic. Once you know the GH, KH and pH of your source water, it is not likely to alter that much in the aquarium so fish that are healthiest in such water are better options. You are in Washington state (I presume) so you have very soft water if you are west of the mountains (Seattle, all along the Pacific coast); the water is harder east of the mountains, Spokane and such. I am up- in Vancouver area, and our water is also very soft. So this is your starting point. The fish species mentioned in post #1 are all soft water, so no issues there. And the acidity of the water (the pH) is irrelevant [meaning from the perspective of adjusting it], let it do what it wants.

Shrimp are a bit different; many need calcium beyond what soft water provides, but some do not. I will leave this aspect alone as I am not a shrimp person. But if the shrimp do need harder water, and they are in a tank without soft water fish, it is simple enough to provide the hardness. Crushed coral is not the best, it is only calcium, but for shrimp it might be adequate. Dolomite provides calcium and magnesium. Or you can purchase salt mixes (not common salt, but salts of minerals like calcium and magnesium). These will increase GH, KH and pH. Back in the 1990's I used dolomite, just two or three tablespoons in a nylon bag in the canister filter of my 115g tank, and it maintained a pH of 6.4 to 6.6 for years. The tap water pH in those days was below 5.

The GH levels you mention are much higher than mine (zero GH and KH) but not a problem for the mentioned soft water fish. But let the pH do what it wants; it will balance out and be stable if the other parameters remain the same.

 

[Bruce Leyland-Jones]

...water is the most powerful natural solvent on this planet

A well-thought out and largely accurate and helpful post, although since you suggested an aversion to myths, legends and half-truths about pH 7.0, I felt the need to address the common fallacy you stated above.
It is very true that simple water can be a powerful corrosive and, given time, can wear down most things. That said, it is because of its generally innocuous nature that its corrosive abilities become something worth mentioning.
Natural hot springs are often full of much more powerful solvents, as the poor fools who decide to go skinny-dipping at Yellowstone seem to discover on a relatively frequent basis!

 

[FF_Member146894]

what
my tap water is 150ppm GH too, but with 8.5 pH
does this mean that i can give up on the whole mixing water business and the pH will "settle out" and lower by itself?
what are the "exceptions" that you mentioned?
at this point i'm confused

 

[Byron]

A well-thought out and largely accurate and helpful post, although since you suggested an aversion to myths, legends and half-truths about pH 7.0, I felt the need to address the common fallacy you stated above.
It is very true that simple water can be a powerful corrosive and, given time, can wear down most things. That said, it is because of its generally innocuous nature that its corrosive abilities become something worth mentioning.
Natural hot springs are often full of much more powerful solvents, as the poor fools who decide to go skinny-dipping at Yellowstone seem to discover on a relatively frequent basis!

I'm not sure I understanding this. But if it is the word "most" that bothers you, I have no problem changing the phrase to "one of the...", and also note I said natural solvents.

 

[Bruce Leyland-Jones]

I'm not sure I understanding this. But if it is the word "most" that bothers you, I have no problem changing the phrase to "one of the...", and also note I said natural solvents.

"...water is the most powerful natural solvent on this planet"
No...it isn't and not by a long chalk.
The contents of the Yellowstone hot springs, for example, are purely natural and extremely corrosive.
Just joining your crusade to rid the world of inaccuracies, fallacies and general typed falsehoods.

 

[Byron]

"...water is the most powerful natural solvent on this planet"
No...it isn't and not by a long chalk.
The contents of the Yellowstone hot springs, for example, are purely natural and extremely corrosive.
Just joining your crusade to rid the world of inaccuracies, fallacies and general typed falsehoods.

I don't see where this matters frankly. No one is going to be harming fish over my statement no matter how accurate/inaccurate, whereas many aquarists do think they need to follow the inaccurate neutral pH "advice," and that is far more serious. Water is not neutral in habitats because of its tremendous ability to assimilate minerals, organics, etc..

 

[Myraan]

Yes, much as I prefer my new JBL liquid test kit to the API - it does try to imply the results might mean you need to PH buffers which "co-incidentally" it sells. (In fairness the API book does exactly the same for their own products)

You can make soft water into hard by adding minerals which will affect pH, or make hard water more soft by diluting it with RO/rainwater which also may impact the pH... but in neither case is changing the pH your goal.

I bet there are people who use a pH indicator in tank to determine how many bubbles of CO2 to squirt in tank a minute, then use the pH bottle from their test-kit, then dutifully run down to the LFS to buy a bottle of "pH up"

 

[itiwhetu]

I don't see where this matters frankly. No one is going to be harming fish over my statement no matter how accurate/inaccurate, whereas many aquarists do think they need to follow the inaccurate neutral pH "advice," and that is far more serious. Water is not neutral in habitats because of its tremendous ability to assimilate minerals, organics, etc..

You do continually tell us that everything has to be factual and be able to be backed up with scientific proof, you even have other members now quoting you. This is one of the reasons I am not posting half of my experiences keeping fish, because I simply don't have the huge amount of reference material you have, But just have experience.

 

[itiwhetu]

I'm going to be very simplistic. An acid tank is almost always going to be better than an Alkaline tank. The great thing about acid tanks is you very really get an Ammonia spike. You can buffer your water up or down naturally, which means you can keep what ever fish you want. Buffer down, making a tank acid use Peat, Plants and Driftwood. Buffer up, making your tank Alkaline use Limestone chip. Easy as that. Stick around 7 pH . On the scale for fish 6.8 is acid 7.4 is Alkaline. Extremes are pH 6 acid or pH 8 alkaline, alarm bells start ringing.

 

[StevenF]

Water leaves the clouds as pure water, but by the time it reaches the ground it is not; water is one of the most powerful natural solvents on this planet, and it readily assimilates substances like minerals (making it harder) or organics (making it softer), and the pH corresponds.

An interesting thing happens to the water as it falls from the sky. It absorbs CO2 from the air as it falls. And if the water is near freezing it saturates with CO2 and will have a PH of about 5 or less.

My pH in every tank I have is low and I don't know how to raise it or if I need to. Seems most fish like a pH of 7ish, but my tanks are always around 6. My 30 gallon might even be below 6, the test strip is really yellow.

When you have plantain an aquarium they will absorb nutrients from the water such as nitrogen, sulfates, chlorides, potassium, calcium, magnesium. But the amount they need of each is different. GH is typically from of the calcium, magnesium sulfate and halide salts in the water. Plants need a lot of calcium and magnesium but only small amounts of sulfate and halides.

So as plant consume calcium and magnesium excess sulfates and halide ions build upon the water. Sufates and halides in water make the water acidic. It can easily drop the PH to 6 or a little less.

Calcium and Magnesium carbonates in in the water (KH) . In this case plants need a lot more carbon than magnesium. And as a result as plants grow in water rich in carbonates and low in GHthe PH Can increase as the plants consume the carbonates leaving calcium and magnesium hydroxides in the water. These hydroxides will push the PH up

have seen my aquarium PH go from 7 in the morning to to about 9 when the lights turn off. Once the lights turn off the hydroxides in the water react with CO2 air and convert back to carbonates.Calcium and magnesium carbonates will push the PH back toward 7. Next morning when the lights turn on the PH goes back up

I didn't recognize it for several weeks because I only checked the PH in the morning. However once I checked PH late in the day and surprisingly saw it at 9. Once I understood what was going on the solution was simple reduce the light levels.

For low PH caused by GH putting in crushed coral, limestone or sea shells will react the halides and sulfate and nuetralize the acids. But that will increase GH.

Foryour pH of 6 or most soft water fish should be OK. You could mix in some RO or distilled water with your tap water to reduce the hardness (soften the water) and that could increase the PH slightly. If that isn't enough you could add coral or sea shells to the softened water to stabilizes the PH. without increasing the GH as much.

 

[itiwhetu]

Have a look at these replies that is why you don't understand pH. I don't think I understand it any more either.