100's of Worm type "things" in pump/filter pipe

[PeterP]

I have garden pond of about 2000 litres with some gold fish, grass carp and ghost carp, all seem to be happy and healthy. I notice the pump seemed a bit slow and purchased a new rotor for it. When I removed the screw on elbow to the pump it was full of hundreds of tiny worm like creatures no more than 5mm long and about 1-2mm across and brownish in colour, they were attached at one end to the inside of the pipe the other end being free to wiggle and when they came away they wiggled in a swiming motion.
The infestation was so bad that they had almost blocked the pump outlet. on further investigation I found all the pipes to my two filters were also full of these creatures.
I have had to remove all the pipes, blasted them out with a garden hose, this removed a ball of worms from each pipe, I then imerse the pipes in Jeyes fluid to remove most of the remainder from inside. I am not making it up when I say there where thousands of them, if not more.
I have in the past found a few on the filter spray bar inside the filter but have been shocked by the numbers today and some in a pipe that has only been in use for a few months.
They do not seem to be bothering my fish and only seem to be in the pump to filter pipes and not in the pond. I am concerned that they almost cause a blockage that in the end could cause my pump to fail. The pump is quite powerful at 2000L and hour and both filters have germicidial tubes in. The pond water is crystal clear and the blanket weed killer is working.
Any ideas what they are and what I can do about them?
I know they are not red worms.

[sidewalkdoctor]

Could be wrong but to me it sounds like Mosquito larvae....

[PeterP]

Originally Posted by sidewalkdoctor

Could be wrong but to me it sounds like Mosquito larvae....

Thanks for that sidewalkdoctor but I thought they had a larger head and swam to the top of water for air. These "things" a fixed enough to the inside of the pipes strongly enough to resist the pump blowing through 2000L and hour. I can see no evidence of them in the actual pond.

[Red Squirrel]

In the filters of our koi pond we have hundreds of blood worms but you say that the one's in your pond aren't red so I don't know what they could be Peterp.

[PeterP]

Originally Posted by Red Squirrel

In the filters of our koi pond we have hundreds of blood worms but you say that the one's in your pond aren't red so I don't know what they could be Peterp.

I can only say they are not like the blood worms that I have fished with in the past and I would not describe them a red. If my "thinking head" had been on I would have photographed them. Will have a look in the filter to morrow and see if I can get a picture of one as they are sure to be back.

[AndyC]

Black fly (Simulium) larvae?
They turn up quite frequently in pond pumps I believe.


Andy

[PeterP]

I managed to find some smaller ones in the filter to day. These are shown against a 5p piece.
I have posted it here, could they be chironomidae larva?
http://www.wildaboutbritain.co.uk/ar.../DSCF00045.JPG

[The Woodman]

As AndyC says, they do sound from your description like Simulium larvae being attached at one end.

I once did seasonal work in a salmon hatchery that used water from a fellside stream and these larvae attached themselves to the outlets of the troughs where the water flow was greatest. They were aslo quite content with low light levels within the hatchery building.

[PeterP]

Originally Posted by The Woodman

As AndyC says, they do sound from your description like Simulium larvae being attached at one end.

I once did seasonal work in a salmon hatchery that used water from a fellside stream and these larvae attached themselves to the outlets of the troughs where the water flow was greatest. They were aslo quite content with low light levels within the hatchery building.

Woodman, I think you and AndyC are right. I have spent hours Googling the Simulium Fly/Larvae and eventually came across a Koi fish forum from 2006 where someone had the same problem and was about to replace his pump to discovered the same level of infestation. He posted some very good pictures and they are identical to the larvae I had. The general opnion seems they are a food source for the fish and cause no harm. A heavy infestation can affect water flow but this improves as the larvae pupate, it is also a sign of good water quality.
Thank you to everone who helped me find the answer to what thought was a major problem.

[The Woodman]

Food for fish maybe, beware, some species of Similium can cause nasty reactions when they dine off humans. There's one called the "Blandford Fly" which I doubt you'll get in Northamptonshire as it lives in Dorset that is responsible for many a long term itchy and painful bite.

Glad you've got it sorted.