PUZZLE 134 pH Problem

pH is a measurement of alkalinity and acidity.
The lower the number, the more acidic something is.
For example, pH3 is acidic, whereas pH 10 is alkaline.
So what would pH 0+0 indicate?
Give a one-word answer.
It is not 'acid'.

Hint 1

A pH reading of zero equals acid.
But 'pH0+0' is neither acid nor alkaline.

Hint 2

In fact, '0+0' is not representing a number.

Hint 3

Try looking at '0+0' as letters rather than numbers.

Super Hint

String the letters together to make a word.

Answer for 'pH Problem'

The answer is 'PHOTO'.