you need to use kalkwasser to get your ph to stay between 8.4 and 8.6. start slow by mixing a 1/4tsp to some tank water in a jar and dump into overflow. watch ph it is gonna sky rocket but should level out right above what your ph was before you added kalk. wait 2 hrs and dose again until ph at middle part of light cycle stays between 8.4-8.6 keep it there for a week or two and they will vanish
jw