Originally posted by Psychoparrot

To isyeye and anyone else who suggested methane - guess I could scratch'n sniff! Wouldn't it burn if it was pure oxygen or methane. As one of the ponds hasn't got enough material yet to produce that amount of methane from decomposition, plus the cold - don't think it could be methane.

ignant - the plants are mainly oxygenators - canadian pondweed, hornwort plus bogbean, mint, watercress, iris,waterlilly and rushes. I guess a decomposing alien might produce alot of gas!


Yes, beginning to make sense - plants started producing O2, then rapid temp. drop. The water would freeze on the surface first, trapping O2 bubbles from escaping. More and more O2 would get trapped causing a backup, with that bubble growing in size till limited by frozen water. It would be a while before the plants became frozen or O2 production inhibited so a fresh bubble would build up, until it too, was limited as the layer of ice rapidly travelled downwards. This would explain the apparant layers. As it does not often go from being so mild to so cold in such a short time, O2 bubbles rarely get trapped like this. Makes sense to me.

While I was at school and uni I worked for a small company that actually installed ponds and water features. Most water plants release oxygen in a way that is readily absorbed by the water, whereas rotting vegetable matter just releases it. Also more water can dissolve oxygen almost twice as readily as methane. Cold water especially dissolves much more oxygen than warmer water and plants also take back a small component of that oxygen especially at night. Rotting of vegetable matter does dramatically slow during the colder months but it doesn't stop altogether unless your pond gets frozen through and therefore still produces gases

We used to suggest using oxygenating plants as a way to actually stop bubbles in ponds as the plants can filter out a lot of the nutrients which would normally just rot and more oxygen in the water kills the anerobic bacteria which can often make a pond quite stinky, though like I said above garden ponds always have some rotting matter in them which produce some amount of gas.

In short the bubbles are more than likely methane with a minor CO2 component. If it stinks a little then there will also be ammonium sulphide component (rotten egg gas) as well and quite possibly a little oxygen also. If these gases are totally trapped in the ice then they should be fine but if they're still in contact with the liquid water itself I would suggest making a smal hole and releasing them as eventually this methane can be absorbed by the water also (though not as readily as oxygen) which can in turn can make it toxic. Yes you should be able to light them up - do it at night with a lighter handy.

1littlewolf OK will pop down later and give it a try - certainly don't want the water going toxic.

I have taken care of the ponds, removing autumn leaves and cutting back dead vegatation such has parts of the water lily, leaves and flowers once past their best. The older pond did not even get any filamentous algae last year, the water keeping beautifully clear. As I mentioned earlier, the newer pond was teeming with daphnia in later autumn - could have harvested them for fish food. Unless the situation is desperate I only top them up with collected rain water and both ponds were 'seeded' with a bucketful of pond water and mud from a clean untainted pond that I know. Watercress is happily growing in both - and I would be happy to eat it. Also lots of watersnails. There is no pump involved, just me attempting to keep the water good by maintaining the status quo and limiting amount of nitrates.

I was a bit concerned that most of the tadpoles vanished quickly and I saw very few baby frogs last year, which I put down to the adult newt population.

Will report back re bubble smells!