[pineapple]

Use some H2O2 on the HC daily with a pipette or syringe for delivery. It works. HC is reasonably hardy. Clean out the filter tubes, outlet and inlet piping. Take the opportunity to clean out the filter too and any inline CO2 reactor. Add Tom Barr's favorite advice here too....

Andrew Cribb

 

[pineapple]

If you do a search on this board you will find a number of threads along with associated advice.

Possible causes:

- unknown
- contamination
- inbalance in CO2, nutrients...
- water quality deterioration

The search function is all revealing.

Andrew Cribb