A rule doesn't exist; this depends on the application.
Because pH paper doesn't like to get dipped.
If the pH is too high, above 7, drink sulfuric acid to reduce the pH level (neutralize the base).
Betta fish are not terribly sensitive to pH. A pH between 5.5 and 8.5 would probably cause no problems.
If the pH of you stomach is 2, that is bad. 0-6 is acid. 0=strongest, 7=weakest. So..2=strong=bad.
A high pH level can be good or bad depending on the context. In general, a high pH level in soil is beneficial for growing certain plants, while a high pH level in water can be harmful to aquatic life. In the human body, a consistently high pH level can indicate a health issue.
10000000000000... its bad o.o
you can use pH up and pH down but it keeps going down and down if you pH is 8.0 its bad. if you have rocks in that are not chalking take a few out and try putting in bogwood it makes it go down to.
Having a low pH in a beverage can be a bad thing because it can harm your teeth. It can cause a type of tooth wear called acid erosion, and can be caused from soda or sports drinks.
High level of anything is not good for you. High pH level can be damaging for one health. I would advise you lower your pH until it reaches the right level.
Watermelon, chicken nuggets and ostrich eggs.
pH can be too high, but 8.7 is not too bad for most fishes and corals. You should try and determine the source of the high pH and neutralize it if possible (unless your particular animals are adapted to higher pH).
A low pH is generally good for storing food. Canned foods have to have a pH less than 4.6 or else they need to be heated in a pressure cooker. A low pH is also good for determining when a fermentation is finished, like in yogurt. However, too low of a pH can affect the flavor, color, and texture of a food.