Bluelab PH 4.0 calibration solution 500 ML

A 500 ml bottle of Bluelab pH 4.0 buffer. Intended for setups with several meters or several people.

Shared supply, shared mistakes

A large bottle usually arrives because there is more than one meter, or more than one person measuring. That is exactly when things go wrong that never happen with a single user. Worth thinking about before you put a bottle on a shared bench.

Pouring back. With one user this is a habit you train out of yourself. With four users it takes one person doing it once: the whole bottle is contaminated and everyone afterwards calibrates against a wrong value, with nothing visibly changed.

The cap. A bottle living on a bench stands open more often and for longer than one in a cupboard. That is precisely what ages the liquid.

The date. With shared use nobody remembers when the bottle was opened, so nobody knows whether it can still be trusted.

Three agreements that solve it, at no cost:

• Write the opening date on the bottle in permanent marker. Visible to everyone who picks it up.
• Keep a dedicated calibration pot beside it: pour, use, discard. Never a probe in the bottle.
• Replace it on date, not on volume. A half-full bottle eighteen months old is not a saving.

For one grower with one meter, 250 ml is usually the better choice; you finish that within the year.

Technical Specifications:

• Value: pH 4.0
• Volume: 500 ml
• Brand: Bluelab
• Use: second calibration point, after 7.0

Frequently asked questions

When do I choose 500 ml over 250 ml?
When you will finish it within about a year. Several meters, several rooms or a continuously running monitor justify this size.

Can I split it into smaller bottles?
Better not. Every decant is another exposure to air.

Do I need 7.0 as well?
Yes, that is your first calibration point. 4.0 is always the second point, never used alone.