Confused with degrees hardness, TDS, PPM and micro Siemens? Let me know if this chart helps!
Today my TDS meter arrived. TDS is all about dissolved stuff in the water (for the technically minded that is things like ions, salts, minerals, metals making an amount of Total Dissolved Solids).
The measurement for my pen is in ppm (parts per million which is also mg/L)
Electronically, we can measure this – because the amount of stuff in the water will increase the conductivity of the water. So pure water will have virtually zero conductivity whereas adding salt for example will allow electricity to flow more because it improves conductivity. The meter passes a current through the water and gives a readout in ppm. It takes mine about a minute to stabilise.
Why measure it?
Shrimp (and fish) live in natural habitats with different levels. Some say my shrimp like no higher than a reading of 200 but other websites say they are good to 800! The key things is, when it comes to water changes and things, I don’t want to add water that suddenly changes the tank water value – that could stress my shrimps and kill them. Over time, a natural planted tank will give off higher and higher readings – and it can help me know when to change the water.
My meter cost about £15 so not expensive really.
So we (my PA with me watching) spent the day sticking the pen into a couple of inches of water to see what the reading was. The results were really cool.
- Tap water – 387 (300-500 is very hard water – and yes it does taste horrible!)
- Tap water boiled and cooled – 387
- Filtered tap water (through kettle filter) – 285
- Filtered and boiled – 315
(the gadget has a couple percentage error margin)
So the kettle filter does reduce the amount of stuff in the water – glad we are not spending a fortune for no reason.
- Rain water – 107 (A spring would give about 50-150, distilled water about 0-50)
- Shrimp tank – 274
- Fish tank – 401
So my planted tank habitat is taking the purity up – from 387 (tap water goes in) to 274. (Lower reading = purer water).
Also, 100 ppm difference in what I use to top up the tank is ok – so they shouldn’t get too stressed.
Useful Shrimp keeper notes:
- Leaves and silt add organic dissolved solids to the water.
- Rocks in an aquarium and substrate can add inorganic dissolved solids to the water.
- Water that comes through copper pipes can add copper to the water – and may harm shrimps if too high.
- A shrimp keeper should know what the natural habitats of their shrimps are – to match the TDS.
- RO water (Reverse Osmosis) pushes water through a membrane to filter out contaminants and purifies the water to a very low TDS (less than 50). Equipment is not cheap and beyond a basic shrimp keeper like me.
- Distilled water can bring down TDS. Water is boiled, the vapour rises and is collected as liquid – solids get left behind in the boiled water.