Water is ph 6.5 but tank ph is 8.0...what gives?

[fishfood!!]

I have a shrimp tank (used to be fish) with a piece of mopani wood, caribsea tahitan black sand, and 2 wisteria.

I can not figure out why but the ph is at 8 as long as I can remember. But the water I use and put in is 6.5. Kh of tank is 3-4 and the water is 1-2 kh. What is going on here?

[emoji848]


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[Byron]

A rise in GH/KH/pH usually occurs from calcareous substances in the aquarium. Rock, petrified wood (not real wood), sand/gravel are all possible sources. Additives such as some plant fertilizers may also do this.

Caribsea says their Tahitian black sand is inert, so this means it does not release substances into the water that would/could affect GH/KH/pH.

You should check the parameters of your source water to be certain.

For pH, you need to out-gas the CO2 by letting a glass of water sit 24 hours before testing pH; this should give you an accurate reading for the source water, which you may find is higher than 6.5 (unless you already do this). You do not need to do this out-gas for aquarium water, just tap water.

For GH and KH, if these are your own tests of the tap water, can you verify them with your water authority? Check their website.

 

[Ch4rlie]

What sort of test kit are you using?

This may be a factor in the differences of readings.

What does your local water authority website states for water hardness?

As Byron mentioned already, there are a number of things that can affect ph / hardness of tank water such as certain types of rocks/stones and substrate as well as wood, all sorts of things really.

So basically there needs to be a process of elimination to find out what may be causing your differences in readings.

For example, my tap water is around 8.2ph and around 280ppm hardness on average and yet my tank water is around 7.4ph and hardness around 250ppm, I use a lot of wood, catappa leaves and gravel substrate all these helps to lower the ph and hardness a little so as not to be so high at the the extreme range of the tank livestock.
(I also have fairly high kh which buffers or steadies the parameters so it does not drastically fluctuate)

 

[fishfood!!]

A rise in GH/KH/pH usually occurs from calcareous substances in the aquarium. Rock, petrified wood (not real wood), sand/gravel are all possible sources. Additives such as some plant fertilizers may also do this.

Caribsea says their Tahitian black sand is inert, so this means it does not release substances into the water that would/could affect GH/KH/pH.

You should check the parameters of your source water to be certain.

For pH, you need to out-gas the CO2 by letting a glass of water sit 24 hours before testing pH; this should give you an accurate reading for the source water, which you may find is higher than 6.5 (unless you already do this). You do not need to do this out-gas for aquarium water, just tap water.

For GH and KH, if these are your own tests of the tap water, can you verify them with your water authority? Check their website.

I discovered that if I let the water sit out for 24 hours, it rises to 7.4-7.6 ph. I assume the difference between the tank’s 8.0 and the water’s 7.6 is due to a combination of what happens in the tank from plants, substrate, what I feed the shrimps and water replacement due to evaporation.

I use Costco Kirkland purified water with minerals added for taste (as my tap water here is high in nitrate) so the water has a GH/KH of 1/1. Oddly enough, the tank tests KH of 4. Oh well, if my shrimps are shedding and growing I think I will stop worrying about such issues unless they get sick [emoji40] [emoji848]


Sent from my iPhone using Tapatalk

 

[fishfood!!]

What sort of test kit are you using?

This may be a factor in the differences of readings.

What does your local water authority website states for water hardness?

As Byron mentioned already, there are a number of things that can affect ph / hardness of tank water such as certain types of rocks/stones and substrate as well as wood, all sorts of things really.

So basically there needs to be a process of elimination to find out what may be causing your differences in readings.

For example, my tap water is around 8.2ph and around 280ppm hardness on average and yet my tank water is around 7.4ph and hardness around 250ppm, I use a lot of wood, catappa leaves and gravel substrate all these helps to lower the ph and hardness a little so as not to be so high at the the extreme range of the tank livestock.
(I also have fairly high kh which buffers or steadies the parameters so it does not drastically fluctuate)

I use API test kits and so far I think I get pretty consistent and accurate readings.

Do the catappa leaves really lower ph? I am thinking of getting some for my shrimp tank, as I read that the leaves are really beneficial for shrimp tanks? [emoji848]


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[Byron]

I discovered that if I let the water sit out for 24 hours, it rises to 7.4-7.6 ph. I assume the difference between the tank’s 8.0 and the water’s 7.6 is due to a combination of what happens in the tank from plants, substrate, what I feed the shrimps and water replacement due to evaporation.

I use Costco Kirkland purified water with minerals added for taste (as my tap water here is high in nitrate) so the water has a GH/KH of 1/1. Oddly enough, the tank tests KH of 4. Oh well, if my shrimps are shedding and growing I think I will stop worrying about such issues unless they get sick [emoji40] [emoji848]

First on the pH, that is what I was getting at previously. Dissolved CO2 in tap water will acidify the water thus lowering the pH. Letting the CO2 out-gas will provide a more accurate pH reading, here 7.6 or so. So that explains the "6.5" is inaccurate. The change in the tank is thus from 7.6 to 8.0 which your next comment explains.

The minerals in the water are likely increasing the pH. I would not use this water for fish, but you only have shrimp so I will leave that for others to comment.

Do the catappa leaves really lower ph? I am thinking of getting some for my shrimp tank, as I read that the leaves are really beneficial for shrimp tanks?

Any organic substance, such as fish excrement, dried leaves, fish food uneaten, dead fish/plant matter, will decompose. As this occurs, ammonia and CO2 are produced. The CO2 works to produce carbonic acid which lowers the pH. All of this is completely natural in any water, habitat or aquarium. The extent to which this occurs depends upon the whole water chemistry.

The GH and KH significantly impact this process. The higher these are, the more minerals and more buffering of the pH to prevent fluctuations. Example, in my very soft water tanks of wild Amazon fishes, the basically zero GH and KH means the pH will lower quite a bit. I have fish that live in such waters, so no issues. By contrast an aquarium of livebearers or rift lake cichlids having a substrate of calcareous sand (dolomite, aragonite) will have a higher GH and KH, and this keeps the pH higher. Leaves and other organics will have very little and likely no effect on pH because of the mineral buffering.

In your situation, the GH and KH are low, thus providing very little buffering or so I would assume. But the pH does rise, likely due to whatever is in the water you use, so this might be additional buffering that would counter the effect of leaves.