A TDS pen is a must if you are keeping freshwater fish or invertebrates.
TDS is short for total dissolved solids that are present in the water column.
Every freshwater livestock originates all around the world with various levels of TDS.
By using this product, it enables you to get the correct requirements for your livestock.
This Product is a must for any freshwater shrimp keeper.
The pen is already calibrated and ready to use, simply turn it on, remove the cap and place into the water you are testing.