A hydroceel (Hydroceel is a brandname) is a tube which contains material which can absorb, retain and extend moisture.
As soon as the heating season starts (winter period) you will remove the hydroceel from the piano and places it in the filling bag or in a layer of water. When the tube does not bubble any more the hydroceel has absorbed the maximum of water and you can place the hydroceel back into the piano. From that moment on the tube vaporizes the moisture into the piano and the relative humidity will rise.
After about 4 weeks the hydroceel has lost all its water and you can repeat the action mentioned above. You will have to repeat this every 4 weeks until you do not use the heating system in your house any more. You will leave the hydrocele in your piano until the moment you put on the heating system again and you will have to fill the tube again.
The winter period is the time to use the hydroceel other periods this is not necessary because the relative humidity is high enough.
The lifespan of a hydroceel is between 8 and 10 years. After this period the material in the hydroceel losts its function and you will have to replace the hydroceel.
We advise you to use a hydroceel in combination with a hygrometer so you can have an indication of the relative humidity in your piano.
The hydroceel-set contains a Hydroceel (tube - 2 pieces of 50 cm), installation material, filling sack and user guide.