Sand Filter takes a week to clear pool

Jump to latest Follow Reply
Q

Quant

Well-known member
Apr 9, 2018
56
Gilbert, AZ
My pump was down for about while before I could fix so I have a very cloudy pool. I started the SLAM process but from recent experience I know it takes about a week of constant pumping for the water to go from very cloudy to crystal clear and that is a long time to maintain the chlorine levels ($$$). After the initial backwash, in about 12 hours, the pressure really does not move up for the rest rest of the SLAM suggesting to me the filter is not filtering much given how much there is to take out of the cloudy water. I have started to experiment with the paper fiber additive to the filter to increase its filtration and after wasting a lot of it by using too much I find I can get the pressure to start to slowly rise with about just 3oz added requiring a backwash in about 12h hours. Adding any more than that and it gets to overpressure in a just a few hours. I assume, as the pool clears, this feedback loop will be change requiring more fiber or longer pumping to get to overpressure..

I paid to have my sand replaced about 4 years ago, and topped off my sand level last year myself. It was 2-3 inches low.

Questions:

How quickly should a sand filter clear a green pool under SLAM?

What is the optimal change in pressure you want to see while clearing a green pool? Seems like going days and days with a cloudy pool with no pressure change is wasteful of energy and chlorine.

Last, I noticed that the filter can be overpressure, or even +5-6 psi, and the act of shutting off the pump causes the water to flow back some and it resettles the solids in the filter such that the pressure returns to the lower starting pressure when turning it back on and not not having backwashed. Should I backwash when this happens or is it fine to wait for it to get back to +10 on its own?

Thank you in advance.
 
Quant said:
How quickly should a sand filter clear a green pool under SLAM?
Click to expand...
This varies by pool, condition of the water, and efficiency of the pool owner to maintain the SLAM protocol. Some owners are very fortunate to catch an algae bloom early and only need to go about 3-5 days before passing the OCLT, while others can take 2-3 week. Just depends.

Quant said:
What is the optimal change in pressure you want to see while clearing a green pool? Seems like going days and days with a cloudy pool with no pressure change is wasteful of energy and chlorine.
Click to expand...
We look for an increase of about 25%. of the clean psi That's when it is time to backwash. Since sand filters seem to filter best when they are slightly dirty, adding the DE as you described should help to capture the very fine particles.

Quant said:
Should I backwash when this happens or is it fine to wait for it to get back to +10 on its own?
Click to expand...
I would wait and backwash when the filter is operating like normal without down time.

Have you passed the Overnight Chlorine Loss Test yet? That's a key indicator to let you know you have killed the live algae.
 
Last edited by a moderator:
  • Like
Reactions: Quant
Reading between the lines it seems you are relying mostly on filtration to clear your pool............I suggest you think of it differently.

Chlorination is the primary factor in clearing your pool. A pool that is not chlorinated properly will perhaps stay cloudy forever.

Chlorination kills ALL the organics and THEN filtration clears the pool.

Trying to deviate from the SLAM process to save on chlorine may never completely clear your pool.
 
  • Like
Reactions: JJ_Tex, Quant, Bperry and 2 others
JamesW said:
Even if your pump is down, you can maintain the correct FC and the pool will not go green.

Follow the SLAM procedure.

What test kit do you have?

SLAM Process

Test Kits Compared

Click to expand...
This ^.

My pool pump has been off and pool uncovered since December and my pool is not yet green because I’ve got chlorine tablets in a floater in there. In fact I just had to start adding liquid chlorine as it’s been getting warmer and I don’t want my CYA going up much more.
 
  • Like
Reactions: Newdude and JamesW
Thank you all for the replies and I think this gives me what I need.

I agree that the keeping the SLAM up affects the process and keeping normal CL levels will keep you from getting to the point where you need to SLAM at all. After about six years of pool ownership I started dropping the ball on that more often in the last year, especially in the off season or when I had mechanical problems, but I do understand it. My layman's view is that chlorine does not just kill but it chemically burns out some of the organics that support microorganisms and the resulting ash in the pool seems to be more attainable to the filter.

Test kit: I started with the test kit that was recommended by this website (TF-100 from tftestkits.net) and I now just replace chemicals as I need them. I don't replace the whole kit, or use their refill kits, since I don't use everything in the kit and rarely need to order everything at once. Though I do need to order some new cylinders as the DPD powder has stained my chlorine test cylinder badly. I usually get new PH and CL test chemicals once a year, buy a big bottle of CYA solvent every few years. Admittedly, I don't replace the other test chemicals as often, like those for testing hard water, and total alkanlity, but I probably need to refresh those as they are getting a bit old.

For Chlorine I use only the R-0871 Reagent with the DPD powder for simplicity and the other methods of testing cl with strips or the other reagents do not seem to measure well the high CL levels I need in Arizona pushed up by the higher CYA in the UV intense summer months. Basically I know my pool well enough to know when there is "a little" chlorine, which is what the non-DPD test tell me, but I need the DPD test to tell me if I have enough, even when not in a SLAM.
 
  • Like
Reactions: Texas Splash
Quant said:
Basically I know my pool well enough to know when there is "a little" chlorine, which is what the non-DPD test tell me
Click to expand...
I use it exactly the opposite from that. 'Do I have enough chlorine for today ?' And the answer is yes. Tomorrow too. The next day and maybe even the next day as well.

216205.jpg
 
Newdude said:
I use it exactly the opposite from that. 'Do I have enough chlorine for today ?' And the answer is yes. Tomorrow too. The next day and maybe even the next day as well.

View attachment 556081
Click to expand...
You will note that that scale tops out at 5 for CL and I routinely want to treat chlorine levels above that in the summer and I never liked the confidence I had in that test especially as I was learning. And then when I had more experience, I find that test gives me no new information over simply knowing how my pool consumes chlorine normally. Even in a case such as yours in NY, where you probably get by on lower chlorine levels, I feel like keeping two separate CL test systems is marginal given how easy it is to do the DPD test versus the two sets of chemicals.
 

Enjoying this content?

Support TFP with a donation.

Give Support
Texas Splash said:
Not sure if you saw the post or if you need it, but tftestkits.net is offering a 20% discount through the month of March for TF-Series refills. :goodjob:
Click to expand...
Admittedly I have been using Amazon recently, but I want to support what you do so have bookmarked your site for that. A few years ago, I had trouble finding the link to order chemicals on the forum and though they were no longer offered. Thanks,
 
  • Like
Reactions: Newdude, Texas Splash and JamesW
Quant said:
You will note that that scale tops out at 5 for CL
Click to expand...
Orange is 10+ FC. It darkens like the yellow does from 0 to 10 and then it goes brown around 20.

With a SWG, all I need to know most days is that it's chugging along maintaining me well above min FC. I would never dose from the block test. (y)
 
Quant said:
I want to support what you do
Click to expand...
THANKS. But I need to clear up the common misconception. TFP and TFT are two entirely different entities. One is a charity and one is a business.

The TFP founder saw a need for a test kit with supplies better suited to how we do things, and TFT was born.

Both TF kits have better supplies for how we do things. They're guaranteed fresh and have fast shipping. The owner, available here, also steps in quickly when things go south. Mistakes happen, sometimes beyond their control like UPS/USPS etc. But they make it right as proven by countless public threads here. We reccomend them because they're great for members, both in product and support, not because it supports the forum.
 
  • Like
Reactions: Quant and JamesW
Newdude said:
Orange is 10+ FC. It darkens like the yellow does from 0 to 10 and then it goes brown around 20.

With a SWG, all I need to know most days is that it's chugging along maintaining me well above min FC. I would never dose from the block test. (y)
Click to expand...
I thought the scale the right is for Bromide. Looks like I have been reading it wrong, I will give it another look as its not clear to me how this works given the graduated yellow color. Though I am still not sure why it's a good idea to keep two ways of testing chlorine, when DPD is so easy. Thanks,
 
Newdude said:
THANKS. But I need to clear up the common misconception. TFP and TFT are two entirely different entities. One is a charity and one is a business.

The TFP founder saw a need for a test kit with supplies better suited to how we do things, and TFT was born.

Both TF kits have better supplies for how we do things. They're guaranteed fresh and have fast shipping. The owner, available here, also steps in quickly when things go south. Mistakes happen, sometimes beyond their control like UPS/USPS etc. But they make it right as proven by countless public threads here. We reccomend them because they're great for members, both in product and support, not because it supports the forum.
Click to expand...
I support TFP of course, and promote it often on people asking pools questions on social media and I understand the test kits are seperate. I support both, but thank you for the clarification.
 
  • Like
Reactions: JamesW and Newdude
Quant said:
I thought the scale the right is for Bromide
Click to expand...
It is. The labeled 10, and everything on the right side column under 'Br' is Bromide. The solution darkens yellow from 0 to 10 FC, eventhough the block only goes to 5. Then it turns orange like the pic I posted and darkens orange from 10 to 20 FC. It's not exact, but at that point, you won't be hitting minimum FC today. Some of us use it as a spot check just to know we aren't needed today.
Quant said:
Though I am still not sure why it's a good idea to keep two ways of testing chlorine,
Click to expand...
Your way is GREAT. :)
 
  • Like
Reactions: Quant and JamesW
Quant said:
I thought the scale the right is for Bromide. Looks like I have been reading it wrong, I will give it another look as its not clear to me how this works given the graduated yellow color. Though I am still not sure why it's a good idea to keep two ways of testing chlorine, when DPD is so easy. Thanks,
Click to expand...
You don’t need both. I’ve never used the yellow OTO test after I got a FAS-DPD kit. I know some people like the OTO test for quick checking but it’s not much longer to do the powder/drops when I’m already doing other tests. If you like both, go for it.
 
  • Like
Reactions: Quant
You must log in or register to reply here.
Thread Status
Hello , This thread has been inactive for over 60 days. New postings here are unlikely to be seen or responded to by other members. For better visibility, consider Starting A New Thread.
Top Bottom
Back
Jump to latest Follow Reply