Need help with a problem. Precipitate on bottom of pool

Hi All,
I recently installed a Pentair Whisperflo 3/4 HP pump and a 48sqft FNS plus DE filter. I went on vacation 1 day after the install. I returned 4 days later to a pool that was 90 degrees (when I left it was 70) and a very hazy pool. Turns out while I was gone one of my relatives came over, turned the heater on and didn't shut it off. Compound the high pool temp with 95 degree temps and I had zero chlorine. Last night I added 3 gallons of bleach and it brought the FC to about 8ppm.

Now the pool is clear but I develop sediment on the bottom of the pool. I vaccum it up with my blue diamond but it returns a few hours later. What is this precipitate? I am thinking it's either dead algae or something, even though the pool wasn't green or DE.

I am concerned because the pump is on a timer and if the heater was on when the pump shut off could it have damaged the grids? I plan to backwash tomorrow and inspect the grids but the filter is brand new so I am hoping not to find anything unusual.

Any advice appreciated.

Joe

This will at least bump the post to the top. Can't answer your all of your question except that shutting off the pump with the heater on should do no damage at all. With gas heaters it is routine to control the pump and let the heater do its thing. Heaters have overtemp and flow switches to kill the gas as soon as flow stops. If flow switch fails then overtemp safety should kick in. Also, the heater should be downstream of the filter so there should be no interaction.
Al

It sounds like dead algae to me. It can take a while for all of it to filter out. What are your chem levels?