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TDS pen recommendations

uk_sjo said:
How would one go about avoiding that in a tap water scenario?
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you can't avoid what comes out of the tap unfortunately. If this was a recurring problem, you'd perhaps want to invest in an RO system or buy RO from LFS, then remineralise to what your livestock require
 
uk_sjo said:
How would one go about avoiding that in a tap water scenario?
Click to expand...

By far the most common scenario would be a seasonal change in the calcium content (usually CaCO3 derived from limestone, which will change both your dKH and dGH). As an example, where I live the the municipal water is a mix of ground water and surface water from nearby lakes (we got a lot of relatively clean lakes in Minnesota). The ratio between lake and ground water changes over the year depending on rain and snow fall throughout the seasons - so sometimes, such as dry summer months the municipal water gets quite a bit softer due to a higher ratio of lake water which are usually quite soft. For me personally, it's not an issue as I rely on 100% RODI water.

If you're relying on 100% tap water all year around and you see a significant seasonal TDS increase the only remedy would be to blend in RO or rainwater. Conversely, if you see a significant decrease you may want to add additional minerals such as Calcium, Magnesium and possibly Nitrate (if you are partially relying on the tap water to supply NO3). If you're using partial RO and partial tap water you may want to change your RO to tap water ratio accordingly.

While the TDS meter will give you a hint that things changed, you can only determine what actually changed by measuring individually (with a dKH and dGH and NO3 test kit), Knowing both dGH and dKH you can derive the Ca and Mg content fairly accurately.

Assuming all Calcium is from CaCO3 and content of Iron and other trace metals that would impact the dGH are insignificantly low.

dKH x 7.12 = Ca ppm.
(dGH - dKH) x 4.34 = Mg ppm.

For instance, if you measure 10 dGH and 8 dKH.

The 8 dKH would most likely correspond to 57 ppm of Calcium from CaCO3 (57 / 7.12 = ~8 dKH)
The 10 dGH would most likely correspond to the 57 ppm of Calcium coming from the CaCO3 plus an additional 9 ppm of Magnesium (plus some insignificant trace amounts of iron etc.) such that 57 / 7.12 + 9 / 4.34 = ~10 dGH.

Note: in the UK its common to have very low levels of Magnesium in the tap water so the dGH will be roughly identical to the dKH.


Cheers,
Michael
 
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MichaelJ said:
By far the most common scenario would be a seasonal change in the calcium content (usually CaCO3 derived from limestone, which will change both your dKH and dGH). As an example, where I live the the municipal water is a mix of ground water and surface water from nearby lakes (we got a lot of relatively clean lakes in Minnesota). The ratio between lake and ground water changes over the year depending on rain and snow fall throughout the seasons - so sometimes, such as dry summer months the municipal water gets quite a bit softer due to a higher ratio of lake water which are usually quite soft. For me personally, it's not an issue as I rely on 100% RODI water.

If you're relying on 100% tap water all year around and you see a significant seasonal TDS increase the only remedy would be to blend in RO or rainwater. Conversely, if you see a significant decrease you may want to add additional minerals such as Calcium, Magnesium and possibly Nitrate (if you are partially relying on the tap water to supply NO3). If you're using on partial RO and partial tap water you may want to change your RO to tap water ratio accordingly.

You can only determine what changed by measuring these individually (with a dKH and dGH and NO3 test kit), Knowing both dGH and dKH you can derive the Ca and Mg content fairly accurately.

For instance, if you measure 10 GH and 8 KH.

The 8 KH would most likely correspond to 57 ppm of Calcium from CaCO3 (57 / 7.12 = ~8 dKH)
The 10 GH would most likely correspond to the 57 ppm of Calcium coming from the CaCO3 plus an additional 9 ppm of Magnesium (plus some insignificant trace amounts of iron etc.) such that 57 / 7.12 + 9 / 4.34 = ~10 dGH.

Note: in the UK its common to have very low levels of Magnesium in the tap water so the dGH will be roughly identical to the dKH.

Cheers,
Michael
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Thanks Michael. I won't pollute this thread (no pun), but I will post my local water report in my build thread in my signature.
 
Well guys, avoid ARKA tds pen 😵

Thing arrived from Olibetta (Germany?) and is unfortunately defective, so it's back to the drawing board!
 
Aqua360 said:
Well guys, avoid ARKA tds pen 😵

Thing arrived from Olibetta (Germany?) and is unfortunately defective, so it's back to the drawing board!
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@Aqua360 , that’s too bad. I’m using the DIST-1 from Hanna instruments. Top notch.

DiST 1 Waterproof TDS Tester (0-2000 ppm) - HI98301

The Hanna Instruments HI98301 DiST®1 TDS tester is a rugged and reliable pocket-sized tester that offers quick and accurate low-range readings of TDS.
www.hannainst.com


Cheers,
Michael
 
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MichaelJ said:
There are numerous posts on the benefits and how to use a TDS meter here on UKAPS. But in short; mainly, you use it to help ensure consistency and stability in your aquatic environment. For instance, you don't want to see your tanks TDS vary much in-between water changes. If you have build-up of fertilizers/minerals, a lot of decomposing organic waste, or leaching hardscape or a varying water source you're going to see a change - typically a spike. You want to avoid that.
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Excellent advice, just keep in mind, organic waste and organic compounds are not registered by these devices.
 
aquanoobie said:
organic waste and organic compounds are not registered by these devices.
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Yes, it depends on the organic compound - and TDS/EC is not a great way to measure DOM (Dissolved Organic Matter), however a TDS/EC meter is an aid that we typically have at our disposal. When uneaten fish food, decaying plant matter, fish poo, dying bacteria and the like decomposes it will eventually free ions thus increase the Electric Conductivity (what we are measuring with our TDS meters) in the water column. Short term, the effect is usually pretty small and of course some of that matter becomes fertilizers and is reclaimed by the plants. If you have a large spike in TDS shortly after a WC it's most likely due to leaching hardscape or substrate and not due to waste, but without any leaching from other sources, a slow increase in EC could point to an accumulation of decomposing organic waste. In horticulture (gardening) for instance, it's a very common thing to add organic matter such as compost and manure to increase the EC of soil.

Cheers,
Michael
 
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