What is this ?

[JustThe12OfUs]

That stringy brown stuff on the bottom? And what, if anything, should I do about it?

 

[linen]

I don't know what it is, but I would clean it out and see if more returns. How do you swg plates look, is there any buildup on them?...this stuff could be from that.

On a side note, we would recommend unplugging the electrical connector to the copper bars (in your picture) since you do not want to add copper to your water.

 

[JustThe12OfUs]

Okay. Tell me where the "plates" and I'll tell you what they look like.

 

[JustThe12OfUs]

Unplug the copper thing? What's it for then? I just followed the set up instructions.

Is the sorta flat thing connecting from the sand box to the outtake valve the 'plates'?

 

[JustThe12OfUs]

Oh wait. The copper things stay there, just disconnect the plug that I would presume charges them? Is that what you mean?

 

[jblizzle]

Oh wait. The copper things stay there, just disconnect the plug that I would presume charges them? Is that what you mean?

Yes.
Although some people have removed the bars completely.

 

[linen]

Oh wait. The copper things stay there, just disconnect the plug that I would presume charges them? Is that what you mean?

Yes.

Unplug the copper thing? What's it for then?

It produces copper ions which act as an algaecide. Unfortunately, copper can stain pool surfaces and turn blond hair green. Good news is, proper levels of chlorine (in your case produced in the generator) is all you need.

Is the sorta flat thing connecting from the sand box to the outtake valve the 'plates'?

That looks like them. There should be no build up on the plates. Make sure you look between them too, you may have to remove them from the container to do so. If you are seeing build-up, that is a chemistry issue.