What is more reliable

[Cjbear087]

So yesterday I tested my dGH with a liquid test and it came out to be 23. Today I bought a TDS meter and it came out as 184. Apparently the conversion is 17ppm TDS = 1dGH. Following that conversion, my dGH should be roughly 11. Obviously, these 2 dont match up at all so I was wondering which measurement would be the correct one. Thanks.

[Lonkley]

Pretty sure you're comparing apples to oranges. Look up TDS but I'm pretty sure it's everything (total after all). Not just gh which I think is just calcium and magnesium. 

Could be wrong. 

 

[Cjbear087]

On 4/13/2024 at 4:58 PM, Lonkley said:

Pretty sure you're comparing apples to oranges. Look up TDS but I'm pretty sure it's everything (total after all). Not just gh which I think is just calcium and magnesium. 

Could be wrong. 

 

Yeah I did think so, just I have heard about the conversions and wasn't sure whats right. Thanks

[AllFishNoBrakes]

Ya, TDS is everything, all the “stuff” in your water, and gH is general hardness or calcium and magnesium. Apples to oranges in my opinion. 

[Cjbear087]

On 4/13/2024 at 5:00 PM, AllFishNoBrakes said:

Ya, TDS is everything, all the “stuff” in your water, and gH is general hardness or calcium and magnesium. Apples to oranges in my opinion. 

Yep thought so. Thank you

[nabokovfan87]

On 4/13/2024 at 8:53 AM, Cjbear087 said:

So yesterday I tested my dGH with a liquid test and it came out to be 23. Today I bought a TDS meter and it came out as 184. Apparently the conversion is 17ppm TDS = 1dGH. Following that conversion, my dGH should be roughly 11. Obviously, these 2 dont match up at all so I was wondering which measurement would be the correct one. Thanks.

TDS is just "stuff"  but GH is very specific minerals.
 

 

[Schuyler]

What's been said any TDS vs GH is correct but if "all of the stuff" (TDS) is reading as less that "some of the stuff" (GH) then that sounds like one of those tests is wrong

[face]

The tds is how much electricity passes through water it try’s to give you a ppm reading but it doesn’t actually know what that different minerals conduct electricity different amounts so it doesn’t know the truth ppm it also won’t read anything that doesn’t conduct electricity tds also can’t pick up anything with to large a size so iron that you can’t see like rust won’t be picked up 

gh is mostly calcium and magnesium but it can also pick up other things like iron but normally that low and don’t really matter 

normally you would expect tds to be high but you there’s a million reasons for it not to be 

 

Edited April 14 by face

[nabokovfan87]

On 4/14/2024 at 7:24 AM, Schuyler said:

What's been said any TDS vs GH is correct but if "all of the stuff" (TDS) is reading as less that "some of the stuff" (GH) then that sounds like one of those tests is wrong

It's definitely not a 1:1 scenario. There are people that think that if you test GH, KH, and TDS when you're keeping shrimp.... That TDS = GH+KH.  It's just hard to really grasp it on some level without having a chemistry set and using solutions. Water isn't just water a lot of the times. There's a lot of "stuff" that skews results and it's just what it is.

I would recommend using GH and KH liquid tests. I don't think anyone should be making tank decisions based on TDS. Basically, TDS is useful only for mixing water.  Each time the meter is used it has to be calibrated, it's a hassle.