# tds help



## Mr P (10 Oct 2013)

hi everyone,i have a tds meter could someone please explain how I can work out the water hardness using it.i am  using ro water with james c remineralising recipe,i am going to keep soft water fish in the tank.any help would be great.many thanks ,roy


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## sa80mark (10 Oct 2013)

Im not 100% and will probably be wrong but as far as im aware you cant convert tds to hardness


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## Yo-han (10 Oct 2013)

It would be possible to convert TDS to KH or GH but not a mixture of both unless you know how much of each is in it. I suggest add a certain amount, test for TDS and test KH and GH. It doesn't matter if it is a little higher or lower. But than again, you can also just remember the amount you added and throw away your TDS meter.


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## Mr P (10 Oct 2013)

thanks for your help chaps,i will still need to get a KH and GH test kit.i can use the tds meter to check my ro unit is working correctly.i am slowly adding ro to the tank and would like to know when I have achieved my parameters.the ro mix is ph7 and tds is 128.where do I go from here?


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## ceg4048 (10 Oct 2013)

Where you go from here is to stop wasting your time worrying about things that do not matter. Soft water fish really do not care what GH and KH are. The whole point of having a TDS meter is to NOT have to worry about measuring GH and KH. Why on Earth would you want to buy more test kits when the TDS meter tells you all you need to know?

Cheers,


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## Mr P (10 Oct 2013)

thanks clive, saved me few bob there.how do I know how hard or soft the water is using the tds meter?sorry to sound thick.many thanks roy.


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## dw1305 (10 Oct 2013)

Hi all,
Roy it doesn't directly measure hardness, but because you start with RO you start with only 1-2 ppm TDS (theoretically it should be 0 ppm, but it rarely is) you can add the buffering salts to give you a datum TDS value.

If you start with the mix at <James' Planted Tank - Re-mineralising RO Water> for 25 litres, and just add that to 25 litres of RO you can measure the TDS and at that value you know have 1dKH and 5dGH.

Other salts you add like KNO3 will raise the TDS, but not the dGH (just multivalent cations) or dKH (just carbonate anions). All TDS meters measure conductivity, rather than TDS, and just multiply the conductivity in microS by ~0.55 to approximate to ppm TDS.

I use an even less precise method for soft water fish, I cut my rain-water with tap-water (about 17dKH) to give about 70ppm TDS (100 - 120 microS). I don't bother measuring anything else, and I use the Duckweed Index to feed the plants when they really need it. 

This method still leaves the water too hard to breed "Blackwater" fish like _Dicrossus filamentosus, _but it is fine for their maintenance.

cheers Darrel


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## Nathaniel Whiteside (10 Oct 2013)

dw1305 said:


> Hi all,
> Roy it doesn't directly measure hardness, but because you start with RO you start with only 1-2 ppm TDS (theoretically it should be 0 ppm, but it rarely is) you can add the buffering salts to give you a datum TDS value.
> 
> If you start with the mix at <James' Planted Tank - Re-mineralising RO Water> for 25 litres, and just add that to 25 litres of RO you can measure the TDS and at that value you know have 1dKH and 5dGH.
> ...



Hey Darrel,

Quick one.

What's the best method of measuring GH? I've got some GH/kh testing kits by tetra in the drawer. I've heard about how inaccurate These types of kits are. Are they even a good approximation? 

Cheers
N


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## Mr P (10 Oct 2013)

thanks Darrel.i am using james c remineralising recipe and I got a reading of 126ppm from the prepared water,if I keep adding this to the tank it will slowly get softer.
 many thanks again. roy.


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## Yo-han (10 Oct 2013)

Nathaniel Whiteside said:


> Hey Darrel,
> 
> Quick one.
> 
> ...


 

No Darrel but I think I can answer this one. I think they are not too bad. Just don't use 5 mL but use 20mL. This way every drop is 0.25 degree instead of one. Now you're close enough to the real deal!


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## Nathaniel Whiteside (10 Oct 2013)

Yo-han said:


> No Darrel but I think I can answer this one. I think they are not too bad. Just don't use 5 mL but use 20mL. This way every drop is 0.25 degree instead of one. Now you're close enough to the real deal!



Sorry, meant API kit. 

But yeah suppose, but I meant another method all together? What's the best/ most accessible?


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