Positive but confusing experience after lowering filtering time

[jodens]

So I have a pretty big 20 x 40 pool that we got redone last summer in our new-to-us house. The pool company said a good rule of thumb for filtering time was at least 2800 rpm for as many hours as the average daily temps. So 8 hours a day in the 80's, 10 hours in the 100's, etc. Well we have a LOT of trees literally feet from the edge of the pool and crape myrtles too so when there's no rotation, all the debris seems to go everywhere and too much of it sinks. So I settled on 12 hours at 2800 rpm and 12 hours at 2000 rpm; 2000 using very little power relatively speaking but keeps the water moving to the skimmers. This has worked well and I didn't have any complaints.
I've been trying to save electricity this summer so I was like, let me try just 12 hours at 2800 and 12 hours off completely and everything has been fine surprisingly. But what I noticed is that I was getting close to needing a backwash before I made the change and immediately after the change my pressure and jet power were back to "just after a backwash" levels. A fresh backwash and new DE at 2800 rpm reads 18 psi and slowly over a few weeks at about 24 psi the jets become almost useless and I backwash. How has simply not filtering for 12 hours returned everything back to 18 psi and full jet power??

 

[Newdude]

hey Jodens and Welcome !!!

I don't have DE but even so it seems odd what you are experiencing. What I can tell you is that the rule of thumb you were quoted is a bunch of malarkey. Any pool only needs enough skimming/filtering to remove the large particles that dont sink entirely to the bottom. With less trees/dirt etc it is far less time to do so. Most pools skim and filter just fine at 1200 RPMs and cost next to nothing to do so. Mine is so cheap that we leave it running 24/7 at low RPM just to see the water ripple.

Dial that bad boy back and try 12 hours. Adjust from there if you see particles floating. If you have a SWG you have to run 100 RPMs above where the SWG turns on to allow for flow variances, dirty filters etc.

 

[JamesW]

When the pump is off, the DE can fall off of the grids and get redistributed. This lowers the pressure.

 

[Richard320]

What happened is the DE fell off the grids. And then when it turned on again and everything got stirred up, the powder stuck to the grids and the sand and whatnot stayed in the bottom. When you never shut it off it never fell off. At least that's the theory in this promotional video.

 

[JamesW]

It's the same basic principle used in the "bump" filters.

 

[jodens]

hey Jodens and Welcome !!!

I don't have DE but even so it seems odd what you are experiencing. What I can tell you is that the rule of thumb you were quoted is a bunch of malarkey. Any pool only needs enough skimming/filtering to remove the large particles that dont sink entirely to the bottom. With less trees/dirt etc it is far less time to do so. Most pools skim and filter just fine at 1200 RPMs and cost next to nothing to do so. Mine is so cheap that we leave it running 24/7 at low RPM just to see the water ripple.

Dial that bad boy back and try 12 hours. Adjust from there if you see particles floating. If you have a SWG you have to run 100 RPMs above where the SWG turns on to allow for flow variances, dirty filters etc.

I would love to run lower rpm but I used to do 1500 rpm for 24 hours and it just wasn't looking good. I switched to 2800 and it all cleared up and stayed clear. I must mention that I only have 3 jets on 1 long side and 1 jet on both short sides before the skimmers so 1 long side has nothing. With a low rpm a lot of surface debris just kind of hung out. I will try some lower rpm's at 12 hours and see what I can do. There is constant leaves, branches and crape myrtle blooms falling though which is why I originally thought I was doomed to 24 hour filtering. What is the point of variable speed pumps if only 1 good speed is necessary? I feel like I could have gotten a cheaper 2 speed pump instead.

 

[jodens]

What happened is the DE fell off the grids. And then when it turned on again and everything got stirred up, the powder stuck to the grids and the sand and whatnot stayed in the bottom. When you never shut it off it never fell off. At least that's the theory in this promotional video.

That makes a lot of sense!

 

[Newdude]

What is the point of variable speed pumps if only 1 good speed is necessary? I feel like I could have gotten a cheaper 2 speed pump instead.

Is it just a busy tree time right now, or is it the whole season ? My oaks go in spurts a couple of times in the season. Dusty pollen, then the flower snot things, then more dusty dirt just before the leaves drop and then the leaves drop. In between those times I can run alot less, although we don't for other reasons. When its heavy though, it definitely would take more time. With all pools being different, it could just be your environment leads to heavy pump speeds and time.

In theory we would all use all the speeds at different times and for different purposes but most of us just find our sweet spot and stay there. Its like anything else with lots if options that you'll never use most of them.

 

[jodens]

Is it just a busy tree time right now, or is it the whole season ? My oaks go in spurts a couple of times in the season. Dusty pollen, then the flower snot things, then more dusty dirt just before the leaves drop and then the leaves drop. In between those times I can run alot less, although we don't for other reasons. When its heavy though, it definitely would take more time. With all pools being different, it could just be your environment leads to heavy pump speeds and time.

In theory we would all use all the speeds at different times and for different purposes but most of us just find our sweet spot and stay there. Its like anything else with lots if options that you'll never use most of them.

I never knew trees shed their leaves every day until I owned a pool. The good news is that liquid chlorine lasts forever because the pool is so shaded but with 4 tall crape myrtles, a willow, 3 pecans and an oak just 5 feet from the edge all around, it's a constant daily battle to keep things out of the pool and the skimmers empty enough to still allow suction.
I remember now why I raised the rpms. Back when I ran 1500 all the time the skimming was just ok but I had yellow algae all the time. I doubled the pump speed and it stopped and the skimmers became very efficient. Like, oh, everything floating is actually entering the skimmers now. I'll drop it 100 rpms every few days and see what happens though. One thing I do know is that anything below 2000 and my chlorinator tube won't fill up with water. That's probably somewhat related to the previous algae problem now that I think about it. I remember the jets seeming strong enough at 1500 right after a backwash but once the psi's started to climb a bit they really got anemic fast.

 

[Newdude]

^^^^^ every pool has its own personality for sure. It stinks that yours has a power hungry appetite but RPMs in the 2ks are still 1/4 to 1/3 the wattage of RPMs in the 3ks. And you also answered your own question of needing a VS because you were able to dial it in exactly where it worked best, not just the 2 speeds the factory picked.

 

[pjt]

Remember you can space your run time throughout the day. For example, if you wanted six hours of runtime per day, you can set your pump to run 2 hours on, then 6 hours off, then 2 hours on, etc..

 

[JamesW]

What is the point of variable speed pumps if only 1 good speed is necessary?

Pools often need more than one speed. Even when people can use just one speed, it's difficult to pick a single speed pump that hits the exact right speed or a two speed pump where the high speed and low speed are exactly right. Part of the value of a variable speed is the ability to try different speeds until you find what works.