What is this in water?

[6amswimmer]

I have an endless pool that I drained and refilled with water from a garden hose. I see black sedimentation in the floor of the pool. The water coming out of the garden hose is clear and yet there is also all this black substance in the floor of the pool. What do you think this is?

 

[aussieta]

water coming out of the tap looks clear, but may have small particles that you cant see
until you are dealing with such large quantites
when i filled my pool from city water it had a green tinge to it
you could not see it in a glass of water

 

[HiddenRiver]

I have an endless pool that I drained and refilled with water from a garden hose. I see black sedimentation in the floor of the pool. The water coming out of the garden hose is clear and yet there is also all this black substance in the floor of the pool. What do you think this is?View attachment 88488

I think folks recommend seeing if the material can be rubbed off with a chlorine puck. Do you have a proper test kit that can measure CYA FC and CC etc? This could shed some light.

 

[duraleigh]

Probably dead algae......although it looks a little too black. Does it brush away?