# TDS readings



## billy boy (31 Jan 2012)

Just finished setting up a shrimp tank using Colombo Flora Base as a substrate, After filling it with RO water, I tested the water that was in the tank so I could adjust the tds with MOSURA Mineral Plus, Just to find the tds was already at 160 :? 

I also put some MOSURA Old Sea Mud and MOSURA BT-9  under the flora.

I have a very mature fluval 205 running on it, Filled with seachem matrex and some bio max and just the usual foam and fine wool, And there is no stones in the tank just 3 bits of bogwood and its reasonably planted.

The tds metre is reading fine as i tested the ro water before it went in and it was 0. So could the flora base be altering the tds?  Or even the old sea mud,Or is there something else doing it.  


Cheers


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## billy boy (6 Feb 2012)

Thanks for all the information guy's


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## viktorlantos (6 Feb 2012)

The soils increase the TDS based on my measuring too. Usually a 0 RO water is pumped up to 60-80 with active soils. This happened with my Shirakura soil too.


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## dw1305 (7 Feb 2012)

Hi all,
Sorry for the lack of reply, but I don't know anything about the Mosura products. 





> The soils increase the TDS based on my measuring too


 I'm pretty sure Viktor is right, because RO has no dissolved salts it is an extremely efficient solvent and will dissolve any salts available in the soil. Your TDS meter actually measures electrical conductivity (1microS~ 0.64ppmTDS), pure H2O is an electrical insulator, but as salts and weak acids go into solution its electrical conductivity rises in a linear response. A relatively small amount of solutes raises the TDS a lot, sea water has a conductivity of about 54,000 microS.

The TDS  doesn't tell you what solutes you have however, and it won't be easy to find out. Personally I would try the shrimps in the tank just using the 100% RO. If you want to add calcium or carbonates you could use the re-mineralising solution at _"James' Planted Tank"_ : http://www.theplantedtank.co.uk/RO.htm


cheers Darrel


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## jimmy james (9 Mar 2012)

My CRS tank tds levels are about 240, I do weekly 30% water changes with RO plus gh booster which gives tds of 95 and gh 4, kh 0. When added back to the tank the combined tds is then 180. I only feed the shrimp every other day with Shirakura Ebi Dama and remove uneaten food after 3 hours. A week later the tds has risen back to 240. 

Tank stats are, running for 6 months 30 litres, ph 6.7, kh 5, gh7, nitrite and nitrate 0. Substrate ada amazonia, decor stone, bog wood, lots of moss and other plants, I dose 5ml TP+ weekly. Co2 injection 2 bps. External filter 500lph.
Most people recommend a tds of 100 to 160 for crs and over the last few months I have lost 3 shrimp.

After reading the last few comments can I assume that the soil is leaching salts? Also any ideas what caused my kh to rise?
Thanks


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## dw1305 (9 Mar 2012)

Hi all,


> Also any ideas what caused my kh to rise


 dKH is the measure of carbonates, so it may-be the décor stone has some calcium carbonate (limestone) content. All dissolved salts will add to the TDS, so it could be any of them raising TDS.

I'd try just using 100%RO for your water changes.

cheers Darrel


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## viktorlantos (9 Mar 2012)

I also bet for the decor stone. Also make sure your TDS meter is calibrated. It need to sometimes.

100-200 is not a problem. Some minerals can push up the TDS along the week.


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