DE Filter Strangeness...

RASelkirk

Well-known member
Jul 11, 2015
74
Port Neches, TX
Hi All,

I swapped over to a DE filter from sand almost 15 years ago. Went through the grid cleaning every year, between cleanings it only needed backflushing 2 or 3 times a year. About 2 years back, I started seeing what looked like filter media in the pool, so I ordered some new elements and changed them out (didn't help). Still seeing grayish-beige "dust" in the pool's bottom whenever the Zodiac G3 is not running. This past year, it seems like I'm BF'ing at least monthly if not sooner. Sometimes I can BF one day and overnight the filter has gained 8#. Does the quality of the replacement elements make a difference? They came off of E-Bay: " Pleatco PFS1836 36 sqft Filter Grid Set Pentair FNS36 Hayward DE3620 FS2003"...

Russ
 

Texas Splash

Mod Squad
TFP Expert
LifeTime Supporter
Russ, Pleatco generally has reliable replacement filters. I use them myself. Let's start with a basic question to make sure we rule out the easiest ….. are you 100% sure it's not algae (or dead algae) that's settling and clogging the filter? A dust appearance and pressure increase are early signs. Can you post a recent set of test results just so we can confirm and move to the possible scenario?

Just to confirm, since you're on a SWG, nothing else has been added to the water correct?
 

Jimrahbe

Mod Squad
TFP Expert
LifeTime Supporter
Jul 7, 2014
14,389
Bedford, TX
Russ,

I agree with Pat.. You have all the signs of an algae bloom... Nothing else that I know of will make your pressure increase over night by 8 lbs...

I don't believe that your problem has anything to do with the quality of your grids.

I suspect that this happened last summer and you never got rid of it... When is the last time you did an OCLT?? Overnight Chlorine Loss Test

Thanks,

Jim R.
 

RASelkirk

Well-known member
Jul 11, 2015
74
Port Neches, TX
What's an "OCLT"? That I don't know could possibly mean never. o_O It could be algae, usually (here in SETX) it's mustard algae which is easily discernible visually. I used to get it all the time with the chlorine/sand setup. The pool is a couple years past it's last repaint, if you brush hard enough you'll see whitish powder come off the walls. I usually only brush a couple times a year. The water is so pretty it's hard to imagine algae, but that would definitely explain the pressure problem. Since going to DE/salt, I've not really added anything other than occasional adjustments to PH and hardness...

Thanks!

Russ
 

RASelkirk

Well-known member
Jul 11, 2015
74
Port Neches, TX
Well, it looks like algae was the problem! I don't have access to liquid chlorine and the only bleach we have here is "scented" or with other unknown additives. I super-chlorinated overnight 3x's so far over the last 10 days and my free/total chlorine is finally showing about the same. Prolly once more after this week should do it, at least the filter is lasting as it should now...

Russ
 

mknauss

Mod Squad
TFP Expert
Bronze Supporter
May 3, 2014
22,404
Laughlin, NV
Home Depot typically has 10%. It may be a little old but since it has been cool should still be good. There is one in Beaumont.

Using your SWCG will not work.
 

proavia

LifeTime Supporter
TFP Guide
Feb 6, 2015
1,614
Chandler AZ
Walmart has Pool Essentials 10% liquid - just check the Julian dates to be sure it's fresh. Some members have reported the Walmart cleaning bleach (6%%) can be had for a good price.
 

RASelkirk

Well-known member
Jul 11, 2015
74
Port Neches, TX
I had to add for alkalinty, calcium, and CYA. Water is balanced now, turned of my SWG, tripped the timer dogs and added 2 gals of 12% liquid shock. After a full turn-over (~ 5 hrs) I'm seeing around 10 T-Cl on my strip. I know they're not accurate and the calculator says I should be at 14. ASSuuming I'm actually at 14, would this be considered sufficient?

Also I have ~ 20# of 3" tabs that are a year old, what are your thoughts on using them in a floater until they're gone instead of the SWG? My CYA is always waaay low and this may help prolong the next dose of additive...

Russ
 

mknauss

Mod Squad
TFP Expert
Bronze Supporter
May 3, 2014
22,404
Laughlin, NV
I would not use the tabs until you have a full test kit to properly assess your water chemistry values.

They do add chlorine and CYA, but are also very acidic.
 

proavia

LifeTime Supporter
TFP Guide
Feb 6, 2015
1,614
Chandler AZ
Without a proper test kit, you're just guessing. Have you considered ordering a TF-100 Testkit or a Taylor K2006C (yes, the 'C' is important. And since you have a SWG, it would be beneficial to have a Taylor K1766 Salt Testkit - or at a minimum Salt Test Strips.

Using a test strip to check chemical parameters (with exception of salt levels) is a wild guess at best. The investment in a quality testkit (and possibly a SpeedStir) will save you major dollars in the long run.

As @mknauss said, tabs add chlorine, CYA and lower pH (acidic). They also wouldn't be a first choice for doing a SLAM Process. And your SWG isn't up to the task either. You need liquid chlorine/bleach and a good test kit.

Also, please post a full set of test results - saying the water is now balanced and not providing accurate test results doesn't help us help you.

FC
CC
pH
TA
CH
CYA
Salt
Water temp (for figuring CSI)


We can help you clear your pool and help make it Trouble Free - but you need to furnish test results from one of the two test kits mentioned (TF-100 or K2006C).