What are the consequences of very high silicate levels?
What does a darker blue than printed on the chart of the silicate test kit (SiO3) mean? Is there a higher probability of diatom growth in this case?
high silicate levels indeed support diatom growth, but that's it. Silicate is not toxic and does not have any other (i.e. besides supporting diatom growth) harmful effects in aquariums - in some regions it is even added to the drinking water on purpose. Drinking water regulations (at least in various countries) accordingly do not even include a limit level.
Dr. Bodo Schnell