I have used an Intex salt water system for many many years with great results each year. I used to use a filter pump before.
Last year I began using the Intex sand filter for the first time. Because I live in New England, I store the pool and hoses in the garage; The Salt Water system in the house; and the sand filter pump in a Rubbermaid shed outside, after I drain it and cover the openings to prevent anything from getting in the sand.
This year, suddenly, there was a bad smell from the pool water. The water is crystal clear and there was nothing rotting anywhere or anything like that. The pool looks great. This is the first time a swamp pond smell happened in all the years while using Intex pools (various sizes) and the salt water generator. The only difference between then and now was the new filter system - now using sand instead of a filter cartridge.
So I looked online for clues on why the pool water could have such a bad smell. One person says to check the sand filter and if it there is black stuff in there. So I backwashed/rinsed the sand filter process, then after that was done I opened up the sand pump. There was black chunky stuff in there on top of the sand in clumps here and there. It grossed me out. Not sure if it was mold, but it must be it.
The sand is the right type of filter sand and it was new last year (purchased from a pool store).
I scraped a bunch of it out and then reassembled the system again and did another backwash/rinse cycle. I then opened it up again and more black stuff.
1) Did this black (mold?) develop from storing the filter pump with wet sand (even after draining it last year)? It was stored in a Rubbermaid shed.
2) Is it normal to have black clumps of stuff in a sand filter?
All last year with the new sand filter pump, I think I only backwashed/rinsed it out 2-3 times during the entire summer. Because this was so new to me, I was a little unsure about the sand filter process. But still, the water looked great and smelled great all last summer. (I only used the salt water generator all these years. Never had to add any other chemicals. The pool water looked great and it never bothered us.)
So, after I opened the sand filter the second time, I pulled out the center unit accidentally on top of the sand. Now I have no choice but to remove all the sand to reassemble the center piece.
I might as well put new sand in now since I have to remove the current sand in there.
3) How do you properly winterize this Intex sand filter in New England?
4) How do you prevent the black stuff from occurring again?
I am tempted to give up on the sand filter and use the cartridge filter system again. At this point, it seems to be less of a hassle. All I used to do with that was just rinse the cartridge and replace. Done.