Newbie here...
TLDR:reddish brown stuff came out of return jet after filter had been off for 2-3 days...is it algae?
With the rain, our pool filter hasn’t been running for maybe two days. I just turned it on and out of the return jet came reddish-brown...something. After a minute or so it was clear again. Whatever it was had to have been inside the (sand) filter (or settled in a hose maybe?) Could algae have been growing in the filter while it wasn’t running? The free chlorine level was at 13 the day I shut off the filter so I would think algae wouldn’t be able to grow?
Other info it it helps....
We had a nasty algae bloom several weeks back..I fought it for over a week (with algaecide and shock from the pool store) before I gave up and just overloaded it with chlorine
The free chlorine level was at 30+ for several days, but that finally seemed to do something. It changed the green water back to clear anyway. Then I used a flocculent (pool store again) and it took 3-4 days to vacuum all of the reddish brown stuff off the bottom. I assumed that was algae?
AAAAnd...that’s actually how I discovered tfp....ordered the test kit balanced the pool out, added the calculated amount of Borax. Aside from being a tad cloudy and the chlorine level hovering around 10, I haven’t had any other problems.
TLDR:reddish brown stuff came out of return jet after filter had been off for 2-3 days...is it algae?
With the rain, our pool filter hasn’t been running for maybe two days. I just turned it on and out of the return jet came reddish-brown...something. After a minute or so it was clear again. Whatever it was had to have been inside the (sand) filter (or settled in a hose maybe?) Could algae have been growing in the filter while it wasn’t running? The free chlorine level was at 13 the day I shut off the filter so I would think algae wouldn’t be able to grow?
Other info it it helps....
We had a nasty algae bloom several weeks back..I fought it for over a week (with algaecide and shock from the pool store) before I gave up and just overloaded it with chlorine

AAAAnd...that’s actually how I discovered tfp....ordered the test kit balanced the pool out, added the calculated amount of Borax. Aside from being a tad cloudy and the chlorine level hovering around 10, I haven’t had any other problems.