What went wrong?

[AliB]

This was my first year with a Hotbin - it started off well but in the last few weeks it has got very squelchy and smelly. So today I emptied it right out. The photos show the difference between the top and bottom. The stuff at the bottom wasn't far off being compost but was quite wet. The stuff at the top is the lighter coloured photo and it was nasty. Any ideas what happened and what I should be doing differently if I give it a go again next year?

[Duffy]

Hi AliB, I am a bit of a novice as I have only just got started properly with my Hotbin, but here are a few thoughts:

I wonder whether the upper part of the bin is getting enough air? If the bottom layer is becoming more compacted as it is forming compost then the air cannot get through. There is a lot of advice on the Hotbin website on possible problems and how to solve them and a lot of the problems seem to be to do with moisture content and air circulation.

How often have you emptied the made compost? I think they recommend emptying it as soon as compost is made: 1 month for mulching grade and 3 months for richer grade. If it has been there longer it may have stopped the air circulating. If it has been emptied more frequently it could be not enough bulking agent. Someone suggested to me, when I was struggling, that I poke holes down into the composting material to introduce better circulation but I ended up emptying the bin instead so I don't know if this would work.

[HotBinDjinn]

This was my first year with a Hotbin - it started off well but in the last few weeks it has got very squelchy and smelly. So today I emptied it right out. The photos show the difference between the top and bottom. The stuff at the bottom wasn't far off being compost but was quite wet. The stuff at the top is the lighter coloured photo and it was nasty. Any ideas what happened and what I should be doing differently if I give it a go again next year?

Hi, the bottom layer doesn't look too bad. It just needs to dry out a bit and it will probably make decent compost. Don't expect to see the fluffy compost come pouring out as you see in advertisements. The top layer has defenetely gone anaerobic. Zooming in on your photo, it looks like there are a lot of undigested leaves in there and I can see them even forming a layer in one place. I think the leaves need to be broken up a bit with a mower or shredder first, this will allow the bacteria access to the internal structure of the leaves and will prevent them from forming a layer that is likely stopping drainage and therefore airflow.

[AncientBrit]

Hi AliB, I am a relative newcomer to HotBins - I bought the larger Mk2 in July this year, so not much experience. But comparing your photograph of the upper layer to how mine looks, there is no evidence of any shredded paper in yours. I use cross-shredded now, having started with strip, and every time I stir the contents it is very visible in the mix. Also, within a couple of days of adding fresh material it is covered with a 'fuzz' of mould which I assume is caused by the action of the bacteria. I always stir the top layer to aerate it and bring up some of the already-composting material to mix with the fresh.

Whatever I do seems to be working, as the temperature of the top layer sits between 50 and 60 degrees all the time.