I have had a starter which i've been using regularly, quite successfully for about 4 years.
recently however its started to really lose its strength; its not doubling in size when i feed it (plain flour) and its not rising my breads. It has a small bit of action, but only a fraction of what it was.
does anyone know what could be causing this or how i could remedy it? Its got a really great flavour to it so i'd love to not lose it.