weird drainage problem

[Friendly_Ben]

My sink isn't draining at all anymore. It was draining abit then i used some cleaning fluid in it and it blocked it completely! Anyway I have a bottle trap and that is clear I also got a 1.8m long metal spring that i have stuck dow the waste pipe and it goes down with out getting stuck except on corners but with some work I cna get it around them. So I assumed the blockage is further along the pipes, but when i put in about about 300-400ml of water the plug whole has filled again. This seems to suggest the water isn't leaving the bottle trap, but it all apears clear.

could there be a blockage further downa dn the air in the pipes is stopping the water going down? I don't know if pressure affects it at all.

Any ideas? Cheers

[ChrisR]

Yes.
SOmetimes air pressure does funny things like that.