Hi all,

I have problem with my water test, especially for the GH. I have performed test with API and SERRA ones, but for each, I could not have any reading of the GH value of my water samples.

All other test KH, PH, NO² are OK, but after 25 drops, I still have the same color in the test tube. Anybody has success with these tests? At least I can have an idea with my band test...

Your GH is probably very low.

Try looking down the test tube from the opening, rather than from the side after one drop.

You might be able to spot a slight colour change when viewing from the top.

I'm not sure@jayc i think@matuva might be describing an extremely high gh if the colour is not changing from the original colour?

Do you have a tds meter? They are not much more expensive than most liquid test kits are and we'll worth it. A good one will do temperature fairly accurately too which I find very handy for matching temps of waterchanges or acclimatising etc etc.

Yup, this is what is weird with these tests: according to the band test - said to be not trustable - the GH is around 4-5.

I have TDS pens. In the local tank, TDS is around 80, in cherries tank, average 170. In both tank, I tried to test the GH with the 2 liquid tests, and the color never changed, from the 1st drop, and until I gave up after 25 drops.

I have another API GH test on the way, I will see what this 3rd one will tell...

If you think the Gh might be super low then double or triple the water volume. Instead of 5ml go 15ml of water and then use the drops. Each drop is 28ppm or something like that in 5ml so it would be 10ppm in 15ml.

11 hours ago, revolutionhope said:

might be describing an extremely high gh if the colour is not changing

Even after 25 drops?

More likely super low, and the change is too faint to notice.

I was thinking that too, but the Serra GH liquid is green. It is supposed to turn red at the 1st drop, and then turn back to green once you reach the GH level. It turns immediately red at the 1st drop, and never turn to green then.
Serra say that if the GH is lower than 1, it will stay green.

For the API, it should turn from orange to green. But it stays orange....

For the 2 brands, the KH test works perfect.

I'm no expert but i find it hard to think you would have such a low TDS and a super high GH. Have you tried a LFS for a comparison? That is my go to before i purchase more of something i already have.

I received my new API test today. It seems this one is working. Here is what I get:

• Rain water : KH: 0; GH: 0; TDS 5
• tap water: KH: 4; GH: 5, TDS 78
• "Black & white" tank : KH: 2; GH: 1, TDS: 70
• RCS & CRS tank KH: 3, GH : 10, TDS 184
• Carbon Rili tank KH: 6, GH: 12, TDS: 230
• Topaz tank KH: 6, GH: 8, TDS: 137
• Red Rili, KH: 6, GH: 11, TDS: 176
• Orange tank, KH: 6, GH: 9, TDS: 134

Does it seem to be normal values? I believe the higher is the TDS, the higher is the GH ?

Also, I think I should transfer the CRS to the "Black & white" tank, but the T° goes up to 27° in this tank, so, better to leave them where they are, as their actual tank stays around 24°?

 

Hey @matuva.That seems more like it!

Although I did notice that as 1 degree of KH or GH is approx 17ppm the reading for tap water, the topaz, red rili and the orange tank data is a bit mismatched somehow.

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Will

They look like the values i would expect. Well done.

Although there is a correlation between GH/KH and TDS i think it is more complicated than 1 to 17. Water chemistry is a science unto itself. Lol

They look like the values i would expect. Well done.
Although there is a correlation between GH/KH and TDS i think it is more complicated than 1 to 17. Water chemistry is a science unto itself. Lol

I am really clueless with chemistry but I know it's possible for the gh or kh result to work out to almost 1 degree less than the total ppm. I also know it's possible for the gh and kh to not add up to the total ppm. I haven't heard of the gh and kh values exceeding the ppm by such a large amount before. I would love to understand these kind of things better..

GH measures the hardness of the water, whereas TDS measures the total dissolved solids in the water.

GH measurement gives you the approximate content of Calcium & Magnesium.

While TDS gives you the approximate content of Calcium & Magnesium, as well as other dissolved minerals, metals, organics, etc in the water.  So apart from Calcium and magnesium, what are some of these dissolved solids that the TDS meter is picking up? 

It will pick up minerals like Sodium, Potassium, nitrogen, phosphorous, sulphur, silicates as well as dissolved metals like Iron, Copper, Lead. It will also pick up Nitrates, and chemicals and pesticides that might be in the water, just to name a few.

So as you can see, GH measurements can reflect TDS measurements if all you have is Calcium and Magnesium. But reality is that you will have more than those minerals in your tank water. So the TDS measurement will usually be higher than the GH measurement, since the TDS meter is made to detect more.