Thick sticky deposit in Aquascape skimmer

[Zayde]

The pond water looks clean, but the skimmer gets clogged every day with a heavy sticky mass. Over the past years I have needed to empty the skimmer no more than twice weekly (except during the leaf-fall season), but now it has to be done every day, and the water flow gets blocked so that the refill control does not work and the pond gets over-full.

Would this be algae ? There's plenty of algae on the rocks in the pond, which the koi happily munch on, but there's no heavy deposit on the bottom of the pond.

What to do ?

 

[Lisak1]

Hi @Zayde !

Tell us a bit more about your pond - how big, how many fish, what kind, how old is the pond, do you have filtration, are you using any kinds of chemicals in your pond? All would be helpful to know in solving this mystery.

 

[MitchM]

What's the colour - brown, grey?
It could be a local buildup of bacteria from a localized food source.
Have you used any additives lately or made any changes to the pond?

 

[Mmathis]

Hi, @Zayde It looks like you were having some kind of algae problem back in 2013. Is this the same issue or something different?

 

[Zayde]

Hi @Zayde !

Tell us a bit more about your pond - how big, how many fish, what kind, how old is the pond, do you have filtration, are you using any kinds of chemicals in your pond? All would be helpful to know in solving this mystery.

Built in 2006 : 1500 gal, koi and goldfish about 30 total - mostly quite small, but a few nice sized koi. The filtration is large fibre mats in a tank above the waterfall. I hosed them down in spring.
The water was very murky a couple of months ago and I used ALGAEFIX, which cleaned it up nicely, but now this heavy dark brown muck developed.

 

[Zayde]

What's the colour - brown, grey?
It could be a local buildup of bacteria from a localized food source.
Have you used any additives lately or made any changes to the pond?

No change to the pond, but I used ALGAEFIX some weeks ago when I couldn't see the bottom of pond, and that worked very well. This new stuff is dark brown, and quite heavy: shaking the skimmer net gets it to collect into a ball.

 

[Lisak1]

I kind of guessed it was dead algae collecting in your filter.

Here's the problem with algaecides - they work great to kill algae. But then you have a pond full of dead algae. And guess what new algae loves to eat? You guessed it - dead algae. Added aeration and lots of plants work great to clear ponds and don't have the side effect of causing more algae growth.

 

[MitchM]

Algaecides don't accomplish anything useful unless you also use heavy aeration and increased filtration at the same time.
Otherwise you only succeed in releasing the nutrients back into the water column, to the benefit of other organisms.
I think the brown sludge you see is a concentration of bacteria that will continue to grow until their food source is gone.
You probably have an increase in Dissolved Organic Matter that the bacteria and other algae needs to consume.
The best you can do is increase overall circulation, and clean the filters until the problem is gone.
If you can post some pictures of the sludge, maybe we can be more sure of it's identification.

 

[GBBUDD]

Action reaction . you killed the algae it had to go some where it would make sence it would mass together.

 

[Zayde]

Hi, @Zayde It looks like you were having some kind of algae problem back in 2013. Is this the same issue or something different?

That time it was a stringy green plant tangle floating in the pond. This time it's a carpet of brown gooey muck choking the skimmer, and there's nothing visibly like it in the main pond. Maybe it's dead plant debris that sank to the bottom and is somehow getting scooped up by the circulating pump.

 

[Zayde]

Thanks everybody for responding. Seems that a very thorough cleaning is the next thing to try. Big job.

 

[Tula]

I think it's also a build up of fish poop Given the size of your pond and fish load, you should consider cleaning the filter more often.

 

[Mmathis]

Thanks everybody for responding. Seems that a very thorough cleaning is the next thing to try. Big job.

That depends on what you mean by “thorough cleaning.”