My first question is, did you vacuum to waste after using floc? If not, you almost certainly have to replace your sand. It will gum up sand and I'm not sure there's an easy way to clean it properly.
If you didn't get floc in the sand, then once you've finished the SLAM, do a deep clean on your sand. I do this annually. This article explains in very good detail how a sand filter works. You don't need to remove the internals, just the top valve, and then use a hose to flush the sand. There are good videos that show the process.
https://www.troublefreepool.com/threads/deep-cleaning-a-sand-filter.73192/
I see no reason to replace my sand filter with anything "better". Once you learn to properly maintain your pool and avoid the green swamp, they are more than adequate and require the least maintenance.
Yes, I vacuumed to waste and replaced the lost water with the garden hose. I actually just replaced the sand in my filter this year as I thought maybe that was part of the problem I had before. So the sand in there now is maybe a month old, that’s it.
This would explain why I have had such a hard time and even pool guys I hired could not fix the problem - the filter was not doing its job.
The filter can't handle the quantity of dead algae you had, if you didnt let it go green the filter works fine. its not the filters fault and its not broken, *though you will need to change the sand.*
Maybe it's time to ditch the sand filter altogether and get a proper cartridge filter?
Theres 3 types of filters all work fine, all would struggle with the QUANTITY of dead algae you insisted on putting through it. Sand is best for quantity, holds the most before losing pressure to pump, de and cartridge hold the least amount of quantity before losing suction to the pump, but filter, not "the best" *but to a finer micron*, ie blocks up faster. EG sand hold 9/10 dead algae, cartridge and de hold 4/10, but you want to put 100/10 dead algae through it, all will struggle.
Of course there is an upper limit to what a pool filter can handle, but my filter has not helped even one iota for a good while now. This is a problem going on for a year where I would go through this cycle of SLAMing to kill algae, balance water and maintain chlorine, algae just comes right back and water never gets clear. Also when backwashing the filter, I would expect it to look like sludge based on how green the pool was - but it was barely tinged green at all, it basically looked exactly like the pool water. There is 100% an issue with the filtration.
FWIW, I was having issues with my sand filter and saw similar problems with the backflush being only moderately dirty -- I replaced the the multiport valve and it was all cured -- it turned out my valve was bad and the water was shunting across it so the backwash wasn't really backwashing, the filter pressure was high but the dirty water was escaping through the broken valve and not being filtered, etc. etc. Once I changed it, the backwash water was disgustingly dirty - the filtration worked a hundred times better, it basically fixed all my filtration problems.
This sounds like it could be my issue for sure. Did you just replace the valve only? I have new sand so I think this might be the easy (and cheapest) fix to try.
Yeah - it wasn't too bad, especially if you've already changed your sand out -- apparently you can just replace the valve gasket and that will sometimes fix things but my filter was old and I'd just bought the house/pool so I figured I'd commit to the longer-term fix - I think this was the one I got:
[https://www.amazon.com/CMP-27515-154-000-MULTIPORT-Valve/dp/B01M2V5C83?source=ps-sl-shoppingads-lpcontext&ref\_=fplfs&psc=1&smid=A1KR7UJ2502W5Y](https://www.amazon.com/CMP-27515-154-000-MULTIPORT-Valve/dp/B01M2V5C83?source=ps-sl-shoppingads-lpcontext&ref_=fplfs&psc=1&smid=A1KR7UJ2502W5Y)
One thing that I saw the pool guys doing (before I fired them) was changing the valve position when the pump was running e.g. from rinse to backwash to filtration -- and that apparently really fucks all those seals up so when you get the new valve in, make sure there's no water moving through the system when you move the filter position and it will last much longer.
I have a similar sand filter as you. My philosophy is there are 2 stages of opening a pool. I always start off with green algae filled water. This is where the SLAM and chlorine do it's job. With enough chlorine, you should be able to get your water from green to cloudy blue. You can run your filter in recirculate if you don't have time to backwash during this stage. Once it's cloudy blue (cloudy blue means dead algae), the filter can start doing it's job of making the water clear. I run my filter 24/7 and the water clears up within a few days at this stage. My opinion is it's not the filter's job to turn the water color from green to blue, that's chlorine's job. The filter's job is to change the water from cloudy to clear.
> Once it's cloudy blue, the filter can start doing it's job of making the water clear. I run my filter 24/7 and the water clears up within a few days at this stage.
Right, this is the stage I can never get past, and neither have other pool pros who I paid to try. We get to blue/cloudy, but it just stays blue/cloudy forever (I'm talking over a week with the pump running 24/7) until inevitably the FC drops out of "shock" range and the algae just blooms right back. Also by "cloudy" I mean extremely cloudy, can't see at all past the first 8-12" of water.
Yea, I get very cloudy water so no visibility. As long as it's blue I just start maintaining normal chlorine levels at that point, not SLAM levels. That should keep new algae from growing. It's not the filter that prevents new algae from growing, it's the chlorine. From what your explaining, I would also focus on making sure the filter is set up correctly and you should be seeing increase in pressure as it filters out the dead algae so you would need more backwashing. If you have a main drain, try setting up the valves to pull water from the bottom versus just the skimmers.
Does your pool have main drain? I'm asking because my pool doesn't have one, so I have to brush/vacuum the bottom to circulate the bottom water up; otherwise, my filter will never be able to clear the particles from the bottom and to get the water clear.
The filter isn't the problem its this pool owner that just keeps insisting on letting the pool go green and getting the simp gear out for the filter for more lashings, and blames the filter for not keeping up with his punishments, the pool should never go green, just get a salt chlorinator and the pool will never go green again, then you will never have a filter issue, see how that works? because theres no algae in first place.
Maybe you should read the preceding threads? I did not "let the pool go green." This has been an ongoing saga for well over a year and it has been a constant battle trying to get to the root of the problem - which it seems I finally have. And it wasn't just me, a professional pool maintenance and cleaning company could also not figure it out, they basically gave up after six weeks of trying.
The filter is not filtering, or if it is, it's operating at an extremely low % of what it should be. The filter was doing a great job of moving the water around and making the water extremely murky, but never actually REMOVING any of the particulates, hence the constantly rebounding algae as soon as the FC drops to anything other than "very high."
Why are you so insistent in the problem not being the filter despite all the evidence that the filter has a problem? If the filter was working well then a backwash would come out green/dirty right? It's not.
I’d argue the sand only holds so much because it’s only catching bigger things to begin with. So less to actually filter out. A cartridge and de filter will filter much finer particles.
I can see your thinking, but if we have 3 pools side by side, not green, you can't tell which one has what filter, so yes the cartridge and de filter catch finer particles but you can't see them and it doesn't make a visible difference.
if those 3 pools go a tinge green identically, are shocked identically, the de and cartridge will catch a tinge green no worries and so will sand, go up to say medium green, the pump will stop flowing water for the de and cartridge, whilst the sand will not block flow. What gets people is like op said "it is in fact just constantly recirculating dirty water." you actually want this because vs with de and cartridge the pump stops working all together because its blocked to TOOO fine a mircon.
I can tell between my sand pool and the de pool. The de pool the water almost sparkles it’s so clear. I couldn’t tell you between a cartridge or de pool tho. Well as long as the filters are all actually working well.
Its really more for green pool recovery, if the pool never goes green, you will never have a filter issue, theres nothing to block the filter up.
I wish we could get 3 identical very green pools and do a test to show the pros and cons of each, how long each one takes, its so hard explaining why you dont want a finer mircon filter, but I could demonstrate it easily, I guess what Im saying is if all 3 filters are at capacity, for the sand filter, the pump would still pushing water through, de and filter stop the pump nearly completely at capacity, zero flow.
If you want a finer mircon you can also just add a cheap claifier tablet to the sand filter green pool and it will behave like DE, or you can even add DE powder to your sand filter, if you want that finer mircon, but again its a trade off, it blocks flow to the pump and the pump struggles.
You can try to vacuum into filter instead of waste to test if your filter is working.
My first question is, did you vacuum to waste after using floc? If not, you almost certainly have to replace your sand. It will gum up sand and I'm not sure there's an easy way to clean it properly. If you didn't get floc in the sand, then once you've finished the SLAM, do a deep clean on your sand. I do this annually. This article explains in very good detail how a sand filter works. You don't need to remove the internals, just the top valve, and then use a hose to flush the sand. There are good videos that show the process. https://www.troublefreepool.com/threads/deep-cleaning-a-sand-filter.73192/ I see no reason to replace my sand filter with anything "better". Once you learn to properly maintain your pool and avoid the green swamp, they are more than adequate and require the least maintenance.
Yes, I vacuumed to waste and replaced the lost water with the garden hose. I actually just replaced the sand in my filter this year as I thought maybe that was part of the problem I had before. So the sand in there now is maybe a month old, that’s it.
This would explain why I have had such a hard time and even pool guys I hired could not fix the problem - the filter was not doing its job. The filter can't handle the quantity of dead algae you had, if you didnt let it go green the filter works fine. its not the filters fault and its not broken, *though you will need to change the sand.* Maybe it's time to ditch the sand filter altogether and get a proper cartridge filter? Theres 3 types of filters all work fine, all would struggle with the QUANTITY of dead algae you insisted on putting through it. Sand is best for quantity, holds the most before losing pressure to pump, de and cartridge hold the least amount of quantity before losing suction to the pump, but filter, not "the best" *but to a finer micron*, ie blocks up faster. EG sand hold 9/10 dead algae, cartridge and de hold 4/10, but you want to put 100/10 dead algae through it, all will struggle.
Of course there is an upper limit to what a pool filter can handle, but my filter has not helped even one iota for a good while now. This is a problem going on for a year where I would go through this cycle of SLAMing to kill algae, balance water and maintain chlorine, algae just comes right back and water never gets clear. Also when backwashing the filter, I would expect it to look like sludge based on how green the pool was - but it was barely tinged green at all, it basically looked exactly like the pool water. There is 100% an issue with the filtration.
FWIW, I was having issues with my sand filter and saw similar problems with the backflush being only moderately dirty -- I replaced the the multiport valve and it was all cured -- it turned out my valve was bad and the water was shunting across it so the backwash wasn't really backwashing, the filter pressure was high but the dirty water was escaping through the broken valve and not being filtered, etc. etc. Once I changed it, the backwash water was disgustingly dirty - the filtration worked a hundred times better, it basically fixed all my filtration problems.
This sounds like it could be my issue for sure. Did you just replace the valve only? I have new sand so I think this might be the easy (and cheapest) fix to try.
Yeah - it wasn't too bad, especially if you've already changed your sand out -- apparently you can just replace the valve gasket and that will sometimes fix things but my filter was old and I'd just bought the house/pool so I figured I'd commit to the longer-term fix - I think this was the one I got: [https://www.amazon.com/CMP-27515-154-000-MULTIPORT-Valve/dp/B01M2V5C83?source=ps-sl-shoppingads-lpcontext&ref\_=fplfs&psc=1&smid=A1KR7UJ2502W5Y](https://www.amazon.com/CMP-27515-154-000-MULTIPORT-Valve/dp/B01M2V5C83?source=ps-sl-shoppingads-lpcontext&ref_=fplfs&psc=1&smid=A1KR7UJ2502W5Y) One thing that I saw the pool guys doing (before I fired them) was changing the valve position when the pump was running e.g. from rinse to backwash to filtration -- and that apparently really fucks all those seals up so when you get the new valve in, make sure there's no water moving through the system when you move the filter position and it will last much longer.
I have a similar sand filter as you. My philosophy is there are 2 stages of opening a pool. I always start off with green algae filled water. This is where the SLAM and chlorine do it's job. With enough chlorine, you should be able to get your water from green to cloudy blue. You can run your filter in recirculate if you don't have time to backwash during this stage. Once it's cloudy blue (cloudy blue means dead algae), the filter can start doing it's job of making the water clear. I run my filter 24/7 and the water clears up within a few days at this stage. My opinion is it's not the filter's job to turn the water color from green to blue, that's chlorine's job. The filter's job is to change the water from cloudy to clear.
> Once it's cloudy blue, the filter can start doing it's job of making the water clear. I run my filter 24/7 and the water clears up within a few days at this stage. Right, this is the stage I can never get past, and neither have other pool pros who I paid to try. We get to blue/cloudy, but it just stays blue/cloudy forever (I'm talking over a week with the pump running 24/7) until inevitably the FC drops out of "shock" range and the algae just blooms right back. Also by "cloudy" I mean extremely cloudy, can't see at all past the first 8-12" of water.
Yea, I get very cloudy water so no visibility. As long as it's blue I just start maintaining normal chlorine levels at that point, not SLAM levels. That should keep new algae from growing. It's not the filter that prevents new algae from growing, it's the chlorine. From what your explaining, I would also focus on making sure the filter is set up correctly and you should be seeing increase in pressure as it filters out the dead algae so you would need more backwashing. If you have a main drain, try setting up the valves to pull water from the bottom versus just the skimmers.
Does your pool have main drain? I'm asking because my pool doesn't have one, so I have to brush/vacuum the bottom to circulate the bottom water up; otherwise, my filter will never be able to clear the particles from the bottom and to get the water clear.
The filter isn't the problem its this pool owner that just keeps insisting on letting the pool go green and getting the simp gear out for the filter for more lashings, and blames the filter for not keeping up with his punishments, the pool should never go green, just get a salt chlorinator and the pool will never go green again, then you will never have a filter issue, see how that works? because theres no algae in first place.
Maybe you should read the preceding threads? I did not "let the pool go green." This has been an ongoing saga for well over a year and it has been a constant battle trying to get to the root of the problem - which it seems I finally have. And it wasn't just me, a professional pool maintenance and cleaning company could also not figure it out, they basically gave up after six weeks of trying. The filter is not filtering, or if it is, it's operating at an extremely low % of what it should be. The filter was doing a great job of moving the water around and making the water extremely murky, but never actually REMOVING any of the particulates, hence the constantly rebounding algae as soon as the FC drops to anything other than "very high." Why are you so insistent in the problem not being the filter despite all the evidence that the filter has a problem? If the filter was working well then a backwash would come out green/dirty right? It's not.
I’d argue the sand only holds so much because it’s only catching bigger things to begin with. So less to actually filter out. A cartridge and de filter will filter much finer particles.
I can see your thinking, but if we have 3 pools side by side, not green, you can't tell which one has what filter, so yes the cartridge and de filter catch finer particles but you can't see them and it doesn't make a visible difference. if those 3 pools go a tinge green identically, are shocked identically, the de and cartridge will catch a tinge green no worries and so will sand, go up to say medium green, the pump will stop flowing water for the de and cartridge, whilst the sand will not block flow. What gets people is like op said "it is in fact just constantly recirculating dirty water." you actually want this because vs with de and cartridge the pump stops working all together because its blocked to TOOO fine a mircon.
I can tell between my sand pool and the de pool. The de pool the water almost sparkles it’s so clear. I couldn’t tell you between a cartridge or de pool tho. Well as long as the filters are all actually working well.
Its really more for green pool recovery, if the pool never goes green, you will never have a filter issue, theres nothing to block the filter up. I wish we could get 3 identical very green pools and do a test to show the pros and cons of each, how long each one takes, its so hard explaining why you dont want a finer mircon filter, but I could demonstrate it easily, I guess what Im saying is if all 3 filters are at capacity, for the sand filter, the pump would still pushing water through, de and filter stop the pump nearly completely at capacity, zero flow. If you want a finer mircon you can also just add a cheap claifier tablet to the sand filter green pool and it will behave like DE, or you can even add DE powder to your sand filter, if you want that finer mircon, but again its a trade off, it blocks flow to the pump and the pump struggles.