Brown "dust" accumulates on floor of pool

[jgerk]

Hi everyone. My pool is four years old. On original sand. Could the sand break down into "dust" after four years? I'm seeing this brown dust accumulate on the pool bottom, at the liner seams, and slight gaps in my underfloor insulation sheets. I vacuum it all carefully, by hand, into the filter, then immediately backflush the filter, but in two days the brown "dust" or silt is back.
Does sand break down? Is the dust or silt coming from the sand? If it's dust from the air, the dust or silt seems so fine maybe sand can't filter it out. Is there an additive I can pour in to encapsulate this type of fine stuff to get it floated to the skimmer and filtered out?
Everything seems to be in good working order otherwise. No drips from anything, pump runs on a timer so a total of 4 hours a day, broken into four, 1 hour periods to increase solar gain. Two adults use the pool every few days for a couple hours, otherwise covered with solar cover.

 

[Shirker]

It is probably not sand breaking down. Could be coming from the air. Or it could be dead algae. I recommend doing an over night chlorine loss test (OCLT). This will tell you if you have a chlorine demand (other than the sun). If you do, you should SLAM the pool to get rid of the algae before it becomes an issue.

Overnight Chlorine Loss Test

 

[TonyM]

I agree - sand lasts longer than we will be around (unless you ask the pool store). Sounds like dust and/or pollen to me, but definitely do an OCLT to be sure.

I get it regularly in Tennessee - mainly starting in June through July. I have to vacuum about every 3 days or so to keep up with it. I live out in the country, with more cows than people in the area. They keep dust in the air. The farmer rolling hay keeps dust in the air. My lawnmower keeps dust in the air. With clay being the main component of middle Tennessee soil, it seems to drop straight to the bottom when it hits the water.

 

[duraleigh]

The chances are about 90% it is dead algae settling to the pool floor, You do not have adequate chlorine in your pool to kill all the algae but you kill some of it and it settles to the floor and accumulates.

You need to SLAM your pool Read the article and ask lots of questions. Many people screw up this process by not following the instructions precisely.

PS - you should only backwash your filter when you have a 25% increase over your clean pressure.