Richard, there are two challenges here. The first is maintain the slam level completely until you are not losing FC overnight. The second is to clear the water.
In my slam which, had high debris load like yours, I had to STOP TOUCHING THE WATER in order to STOP stirring up the silt while the top layers filtered.
While in a normal slam its good to brush etc., in a heavy debris slam that putrified a high volume of particulate matter like leaves, its actually better IMHO to LEAVE THE WATER ALONE, as I suggested earlier, for several days to SEE if it will clear. Especially in your case, where you already changed the filter sand.
Every time you rake, vacuum or otherwise disturb the water right now, including using a cleaner just yet, you're stirring up the silt.
As long as you're stirring up the water, nobody here can accurately diagnose whether you have a problem with the filtering or not.
I'd personally like to see you go from today to Monday without touching the water except to add chlorine and check that your psi is good and your pump basket doesn't clog. But no raking, brushing, vacuuming at all. Take pictures of the whole pool from the same spot each day.
If you've maintained your FC religiously, not touched the water, and maintained correct filtration, I predict your clarity will have increased and silt will drift on the bottom, ready for a very slow, careful vacuum to waste.
If you do those things and this does not happen, then and only then might I offer a different diagnostic suggestion which would remedy.
Btw, if you lose pressure and your water is at the correct level halfway up the skimmer, you don't need to backwash...you need to clean out the pump basket. The only time you should backwash is if your psi increases 25%. Sand filters work better a bit dirty, as I mentioned earlier.
Ok, I will follow your approach. A couple of points, though. First, when my filter clogs, and the pressure goes up, it clogs, and the pump will lose prime. Sometimes the entire prime is lost so that nothing is pumped, and other times , it will be a slow flow. In either event, I have to re-prime to backwash, and rinse. if I have totally lost prime it can take a few minutes to get it going. Once, its going it will flow for X minutes or hours depending on debris (stirred up state), or whether I have added diluted DE to the skimmer basket. An earlier post reply, stated that if I add DE I'll be backwashing every hour or so. He is right ! So, if I am to leave the pump/filter alone, and want it to run, then I should not add DE now, correct?
My filter pump basket very rarely, if ever fills with debris requiring cleaning. My shallow skimmer basket collects the brunt of leaves, while the deep end skimmer collects a much lesser amount of stuff.
Yesterday, when I vacuumed to waste, and did as close of an inspection as possible of the water (cupping handfuls as it expelled), I noticed tiny bits of brown/black debris, and I mean tiny! Nothing large, or obvious, and no muck, brown sediment (other than the tiny bits), leaves, or other obvious items. So I remain convinced that 99% of the gunk is gone. What remains on the bottom is guesswork until visible. One can see about 12-18 inces down at this juncture.
Otherwise, I will let things alone and see what happens. I will have the skimmer ports open and the main drain closed. Yes ? I assume your fellow TFP people agree. I will continue to monitor the FC and add to slam levels. I have been doing this about 5-6 X per day.
Please let me know if something needs change. Thank you for all of your help, suggestions, and support!
- - - Updated - - -
There is nothing easy about cleaning a cartridge filter. It takes about an hour and at least half of that time is spent with a garden hose going full blast hosting off dozens of pleats in 4 different cartridges. I've done it many times.
If you installed a quad DE filter on your pool right now you would have to clean it and add new DE every day.
I've seen people with DE filters and a swamp have to backwash and recharge DE every hour. Or just run it on bypass because they have to go to work and not filter at all all day long.
I appreciate your input because I certainly have no experience with these things. An earlier post stated that he believed that if I had a DE filter things would clear w/in 24 hours. So, again, I only know what people suggest. Thank you for your input because I find your experience invaluable !
- - - Updated - - -
1st thing is to look inside your current filter. I'd want to get the pool cleaner before putting in a new filter. If you're serious about a new filter look at the Pentair Quad DE filter. It has the filtering capabilities of DE with the cleaning ease of a cartridge filter.
Thank you, I will check it out.
- - - Updated - - -
The type of filter has nothing to do with killing algae and clearing up the pool. Any filter will filter the pool. There are thousands and thousands of people who have slammed and cleared up their pool with a sand filter. Chlorine is the only thing that kills algae and clears up the pool. When I had some algae and my pool was barely cloudy I had to take my cartridge filter apart and clean the cartridges every 2-3 days, it took about an hour each time. If you installed a cartridge filter right now you'd have to take it apart and clean it every day. I would have much preferred to be able to just backwash when the pressure rose 20-25%.
Once the pool is fairly clear and the chlorine holds better you can add DE to the sand filter to help it clear faster,
Pool School - Add DE to a Sand Filter. Or you can add DE now but don't leave because you'll probably have to backwash in an hour or less.
I have found that adding DE does create quite a backwashing need !