# Raise the pH of a solution and prevent build up of carbonates

I need to raise the pH of a solution so the easiest approach is to add alkali hydroxides (NaOH, KOH, etc). But as most of you know, the CO$\ce{_2}$ in the air can react with these hydroxides to form carbonates which usually precipitate out the other metal ion dissolved in the original solution. So what else are my options?

How about $\ce{NH4OH}$? This does not for carbonates as readily, but it does form complexes with many metals. It depends on your intended use.