Pond help please

HariboJunkie

I have 2 half barrel ponds at either end of the garden. One is shady and partially sunken and well established (4 years) and has a couple of resident frogs and toads . The birds use it for drinking and bathing and there is currently a fledgling robin and blackbird living in the margins.
The other pond has only been there for 3 months and it stinks. We did have tadpoles in it but they only lasted a week. I have cleaned it out several times but the smell (like sewage) keeps coming back. There is a bit of pond weed in it and a water lily which is doing fine. Today I found a huge toad in the old pond which the frogs don't like so I moved him to the new pond which I had cleaned out yesterday. He seems very happy but I have also noticed lots of larvae in there today. I have identified them as rat tail maggots which are the larvae of the drone fly so beneficial pollinators but they only inhabit foul smelling ponds apparently. Sooo... the questions are.... Why does the pond stink and will it harm the frogs and toads?

Hope someone can help.

alanobrien

Sure something isnt leaching into the water from the barrel or through it ?
If your not sure it may be worth trying to line the barrel with polythene or similar to see if that makes a difference.