Low Gh and Kh

[Jenny32]

Hi,

I have tested our tap water and the Gh is 2 & Kh 0.5/1 - I want to have perfect conditions for my fish so I am willing to add a product to the water to raise these numbers. Should I do this? Fish shops advise that it will be ok cause most fish are breed in captivity and are used to it and can adapt. Should I just buy soft water fish?

Thanks

 

[Byron]

Your water is very soft and therefore ideal for the vast majority of fish in the hobby. If you really want hard water fish like livebearers, then you would have to permanently increase the GH, but while that is certainly doable it is opening up another range of issues. Selecting fish suited to what you can easily and readily give them (there are weekly partial water changes, and emergency changes can occur) makes life much easier, and less expensive.

That advice from stores really is somewhat mythical, though there are some species that do "adapt" for various reasons, but it is not as cut and dried as stores would have you believe. Fish do not change their DNA just because they are captive bred, though evolution can play out over decades in some cases.

Your GH is ideal, and the pH will naturally be low (acidic) which usually goes along with such water in the habitat of soft water species.

 

[mbsqw1d]

It would be worth measuring the PH of your tap water too. Measure it after it has been allowed to stand in a glass for 24 hours. This allows for any co2 in the water to gas off (the co2 would lower the PH and so give false reading).

With low GH and KH, as Byron states, you have ideal water for soft water fish, who thrive in soft and acidic conditions. Many fishkeepers have to go to the trouble of obtaining Reverse Osmosis (RO) water in order to achieve the parameters that are coming out of your tap!

Over time, the nitrification process produces acids that lower the PH in the tank. Something to bear in mind with low PH (under 6) is that toxic ammonia converts to the non toxic form, ammonium. This is absolutely fine, and actually preferable to higher PH setups, because you don't really need to worry about the nitrification process (cycled filters etc). Especially if you have live plants that will absorb the ammonium.
However - once your tank is running as an acidic setup, with ammonium, it is imperative that any new water that is added when performing a water change, does not raise the PH of the tank above 6, as this will start to convert that non-toxic ammonium back into toxic ammonia, and cause problems for the fish.

 

[Jenny32]

Your water is very soft and therefore ideal for the vast majority of fish in the hobby. If you really want hard water fish like livebearers, then you would have to permanently increase the GH, but while that is certainly doable it is opening up another range of issues. Selecting fish suited to what you can easily and readily give them (there are weekly partial water changes, and emergency changes can occur) makes life much easier, and less expensive.

That advice from stores really is somewhat mythical, though there are some species that do "adapt" for various reasons, but it is not as cut and dried as stores would have you believe. Fish do not change their DNA just because they are captive bred, though evolution can play out over decades in some cases.

Your GH is ideal, and the pH will naturally be low (acidic) which usually goes along with such water in the habitat of soft water species.

Thanks Byron, that's reassuring. I was planning not to go for live bearers anyway so that works out well. Thinking about Harlequin Rasboras to start with. Yeah the Ph level was about 6.8 from the tap. But waiting for the tank to cycle and see what the ph level is in the tank.

 

[Jenny32]

It would be worth measuring the PH of your tap water too. Measure it after it has been allowed to stand in a glass for 24 hours. This allows for any co2 in the water to gas off (the co2 would lower the PH and so give false reading).

With low GH and KH, as Byron states, you have ideal water for soft water fish, who thrive in soft and acidic conditions. Many fishkeepers have to go to the trouble of obtaining Reverse Osmosis (RO) water in order to achieve the parameters that are coming out of your tap!

Over time, the nitrification process produces acids that lower the PH in the tank. Something to bear in mind with low PH (under 6) is that toxic ammonia converts to the non toxic form, ammonium. This is absolutely fine, and actually preferable to higher PH setups, because you don't really need to worry about the nitrification process (cycled filters etc). Especially if you have live plants that will absorb the ammonium.
However - once your tank is running as an acidic setup, with ammonium, it is imperative that any new water that is added when performing a water change, does not raise the PH of the tank above 6, as this will start to convert that non-toxic ammonium back into toxic ammonia, and cause problems for the fish.

Thank you, I tested the tap water and it was about 6.8 ph. I'll try testing again after leaving the water for 24 hours and post the outcome. Good to know that I have good water and I don't need to do anything like RO!

 

[Jenny32]

Thank you, I tested the tap water and it was about 6.8 ph. I'll try testing again after leaving the water for 24 hours and post the outcome. Good to know that I have good water and I don't need to do anything like RO!

Thank you, I tested the tap water and it was about 6.8 ph. I'll try testing again after leaving the water for 24 hours and post the outcome. Good to know that I have good water and I don't need to do anything like RO!

Tried testing the water after 24 hours and it's coming up about 6.8/7 I thought it would be lower. But at least it isn't above 7 I suppose.

Thanks for your help.

 

[Byron]

Tried testing the water after 24 hours and it's coming up about 6.8/7 I thought it would be lower. But at least it isn't above 7 I suppose.

Thanks for your help.

That's good. You have a reliable reading now. With very soft water, there is little if any real buffering, so as the organics in the fish tank increase (as is normal and inevitable), they settle into the substrate and decompose. The resulting ammonia/ammonium and CO2 will acidify the water and the pH will tend to lower. All normal and natural. I leave it alone, and some of my tanks have a pH in the 4's, others 5's, one in low 6's, depending upon the individual tank's biology. A stable pH over time--and here we mean months and years of no shifting in pH beyond a couple decimal points--is what you want.

 

[mbsqw1d]

That's good. You have a reliable reading now. With very soft water, there is little if any real buffering, so as the organics in the fish tank increase (as is normal and inevitable), they settle into the substrate and decompose. The resulting ammonia/ammonium and CO2 will acidify the water and the pH will tend to lower. All normal and natural. I leave it alone, and some of my tanks have a pH in the 4's, others 5's, one in low 6's, depending upon the individual tank's biology. A stable pH over time--and here we mean months and years of no shifting in pH beyond a couple decimal points--is what you want.

Byron, on the PH 4 and 5 tanks of yours (assuming your tap water PH is 6+), do you perform small and regular water changes so as to not shift the PH significantly?

 

[Byron]

Byron, on the PH 4 and 5 tanks of yours (assuming your tap water PH is 6+), do you perform small and regular water changes so as to not shift the PH significantly?

No, but I appreciate my situation may be somewhat unique. Our water is 7 ppm GH (which is so low as to be zero by the time it is in the tank), 0 KH with a pH of 7.0 to 7.2 out of the tap. The "high" pH (the reservoir pH is, if memory serves me from two decades ago, below 5) is due to additives, primarily soda ash, to raise the pH to 7 to prevent corrosion in the system. Fortunately, this dissipates out fairly quickly. But there is also the fact that with no buffering in the source water, the individual aquarium water is extremely stable over time. So the water change of 2/3 to 3/4 of the tank volume, which I do every week and have for years, has minimal impact on the pH.

I did test this a few times to confirm. My API test only goes down to 6, so I used the one tank that had a pH of 6.0 to 6.2 normally, and the pH went up to 6.4 or 6.6 post-water change, but the following morning was back to 6.0 or 6.2; since I have zero GH/KH and all very soft water fish, this has posed no issues that I could discern. If I had a tank of harder water species, life would be very different.

 

[Jenny32]

That's good. You have a reliable reading now. With very soft water, there is little if any real buffering, so as the organics in the fish tank increase (as is normal and inevitable), they settle into the substrate and decompose. The resulting ammonia/ammonium and CO2 will acidify the water and the pH will tend to lower. All normal and natural. I leave it alone, and some of my tanks have a pH in the 4's, others 5's, one in low 6's, depending upon the individual tank's biology. A stable pH over time--and here we mean months and years of no shifting in pH beyond a couple decimal points--is what you want.

Thats good to know and if it starts to lower in the tank i'll know why. Good to get advice on here as trying to find advice on websites is pretty hard, there is a lot of contradictory advice out there on different sites!