TDS meter

Performance & sizing

Core numbers for matching this unit to your tank and electrical plan.

Power

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Flow rate

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Noise

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Dimensions

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Price range

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Tank fit (L)

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Consumables & maintenance

Calibrate probes and replace test reagents per kit instructions.

Description

A TDS pen gives you one number in parts per million, and the number does not tell you which solids. Calcium out of a limestone aquifer, sodium from a water softener, nitrate from last week's overfeeding and the fertiliser you dosed on Sunday all push the same reading up. That is the meter's strength and its limit at once. It is a fast way to see that something has changed and no way at all to see what. The one widely published benchmark for the quantity is a drinking-water figure, and it helps to know what kind of figure it is. EPA sets total dissolved solids at 500 mg/L in the National Secondary Drinking Water Standards. Those are non-mandatory guidelines covering 15 contaminants, and EPA does not enforce them. They exist so public water systems can manage aesthetic considerations such as taste, colour and odour, and the agency states that these contaminants are not considered to present a risk to human health at the secondary level. Above the figure, the effects EPA lists are hardness, deposits, coloured water, staining and a salty taste. Total dissolved solids appear in four of that page's effect groups at once: taste and odour, colour, corrosion and staining, and scale and sediment. None of that is an aquarium target, and this catalog does not have one to offer instead. What the pen is genuinely good for is comparison against yourself. Read the tap or RO water going in, read the tank, and watch the gap rather than the absolute value. A reading that climbs steadily between water changes is telling you something real about top-ups and feeding, whatever the solids turn out to be. Calibration fluid is worth buying with the pen, since a drifting meter looks exactly like a changing tank.

Source

• epa.gov — https://www.epa.gov/sdwa/secondary-drinking-water-standards-guidance-nuisance-chemicals

Figures on this page were read off these pages. Manufacturers and databases do change or retire pages; if a link is dead, tell us with the correction link below.