The holes in the internal base plate are full of compost, what should I do?

Tuesday, 4 August 2015  |  HOTBIN Composting

Do I need to remove the compost from the holes in the internal base plate?

The answer is no.

It is normal for the holes in the internal base plate in the bottom of bin to be covered with compost. The plate and holes do not require cleaning out during normal HOTBIN use.

Clear HotBin Aeration Plate
It may appear 'counter intuitive' to leave the compost in the base plate and you may think they must be clear to allow air to flow - but this is not the case - the air flows around the compost particles. The plate works with the compost in and over the holes.  Think about it like this - if you spend ages getting all the bits out, as soon as you reload the HOTBIN the holes will be full again. It has to work with them full.


We have come across one incident where the plate holes were blocked and did not allow water to drain out or air to move up.  The holes were full of a very gooey sludge like material which sat there and did not drip to the base. It effectively plugged the holes with a watery liquid goo allowing not air flow through the hole and the bin stopped.

When analysed we believe it is almost pure humic substances. These compounds form during composting. Because the molecules are water soluble and very small - we believe they are draining to the base over time (4-6 months). This appears to be worse when the compost gets 'too wet' . Because humus absorbs x500 own weight in water water (it is colloidal) it creates a goo (think of this like a heavy clay soil - water is held in a gooey mass). On the positive side - this is black gold (the very best). On the downside it did stop the bin and we can foresee that other incidents will occur.
 

So here are our tips to ensure it remains a very rare event:

  • Empty the bin every 3-4 months minimum. never longer than 6 months.
    The longer the period the compost sits in the HOTBIN, the more humus
    can drain to the base plate.
  • Before first fill and after each empty, sprinkle a thin (1 cm) layer of wood
    chip over the base plate. this will help air flow and water drainage.
  • Do not add soil to the HOTBIN. Clay in the soil will make the situation worse.
  • Place woody pruning's / twigs on top of the base plate to keep composted
    material above the holes to minimise any blocking.

Can i test to see if the base plate is blocked?

Yes - It is very difficult to see if the waste in the holes is normal or super gooey.

Covered Aeration Plate

This photo illustrates how the super gooey material sticks to the underneath - notice the materials is just in peaks - it is not dripping down.

Take off the door and push back the waste and slowly pour half a cup of water onto the middle of the base plate. If the water drains down below plate within 2-5minutes the plate is not clogged, it it just sits on top - then it is blocked.

Please note if your HOTBIN is working at 60°c, by definition the airflow cannot be restricted and the base plate is not clogged.