Best TDS for a planted aquarium?Updated a month ago

Is there an Ideal or Target TDS? No.

This is because TDS is an aggregate measure of all dissolved solids. A high reading is not necessarily good, and a low reading is not always insufficient. For example, 100pm of Calcium in water (high TDS) is relatively harmless while 5ppm of copper (low TDS) will kill most aquatic life.

TDS, or "Total Dissolved Solids" simply measures all dissolved organic & inorganic substances in the water. However, it does not tell us WHAT is in the water. What makes up the TDS value is alot more important than the aggregate reading.

Then why do people measure TDS?

TDS is very useful as a relative test.

It is like a thermometer.
It is useful to check if it rises or falls over time, as the cause may be consequential.

If your room temperature rises sharply, it may be a sign of a breakdown in ventilation or clogged air conditioning. It may be due to the window being left closed or open. It may result from the automatic blinds failing to work. It may be because of an overheated computer in the room.

As a relative test, TDS is useful when adding new hardscape or other materials to the tank. If TDS rises over time, it means that some part of the rock is dissolving. Totally inert rock will not change the TDS value.

Read more about TDS here.

This Seiryu/limestone tank has a TDS of around 350. The water is moderately hard due to carbonates leaching from the limestone. Avoiding species that require very soft water still leaves plenty of choices for a nice aquascape.

For a soft water tank, that is remineralized to 5-7 dGH, the TDS will be around 170 to 200.