SLAM Effectiveness

[rscrouch]

I have a 15,000 pool with a DE filter. I started the SLAM process one week ago because I was losing > 1 ppm of FC overnight - sometimes up to 3 ppm. I have followed the process pretty closely. My water is crystal clear, my CC is zero, and I'm not seeing any algae - alive or dead - in the pool. However, I'm still losing 1-3ppm of FC nightly, so I'm reluctant to stop the SLAM process. Any idea why I'm still seeing the loss? Could it be residual algae in the filter? Should I backwash and then continue the SLAM?

Current readings (Taylor TF-PRO):
FC: 21 (SLAM target: 21)
CC: 0
PH: 7.3
CYA: 52
TA: 76
CH: 425
Water Temp: 76 degrees

 

[reggiehammond]

CYA is only valid on the 10's. Not sure how you came up with 52, hope that's not pool store testing.
Always round up; so your CYA is really 60 for SLAM, Target 24.

pH testing is invalid at FC 10+. TA testing results in values that are in 10's; not sure how you came up with 76.

Algae in filter would already be dead at SLAM levels. Would be wise to take a look behind lights, weir doors, inside skimmer, etc. Any ladders, steps, etc?

Please fill out your signature. Would also help immensely to log poolmath results and share those via built in function.

SLAM can occasionally require a lot of POP. Pool Owner Patience.

 

[Newdude]

Why did you OCLT in the first place ? Was the daytime loss questionably high ?

Any UV or Ozone ?

What's the story with the 76 TA ? I see people guessing a 75 if it seems between 70 and 80, but 76 ?

 

[rscrouch]

CYA is only valid on the 10's. Not sure how you came up with 52, hope that's not pool store testing.
Always round up; so your CYA is really 60 for SLAM, Target 24.

pH testing is invalid at FC 10+. TA testing results in values that are in 10's; not sure how you came up with 76.

Algae in filter would already be dead at SLAM levels. Would be wise to take a look behind lights, weir doors, inside skimmer, etc. Any ladders, steps, etc?

Please fill out your signature. Would also help immensely to log poolmath results and share those via built in function.

SLAM can occasionally require a lot of POP. Pool Owner Patience.

Thanks. I’ll get the signature done. I’m using poolmath, so I’ll use that from now on.

I entered the original post on my phone and somehow fat-fingered the CYA & TA. CYA is actually 50 and TA 90 according to their Taylor test kit.

I’ll check the lights. I’m also going to get in and water blast the rock trim to make sure nothing’s hiding in there

 

[rscrouch]

*the Taylor test kit, not “their”

 

[dereksanders]

Ladders and all other nooks and crannies. If water can get somewhere so can algae.

 

[Newdude]

Take a step back and look for anywhere it's hiding in plain sight. Someone found their auto fill all gunked up a while back that was causing the extended slam. They probably stepped over it 150 times in the process but didn't think to check it.

 

[PoolStored]

It is hiding somewhere:
Scrub skimmers.
Check weirs for algae in foam.
Scrub inside any autofill.
Scrub inside and outside ladders.
Scrub behind lights.
Remove any main drain covers and scrub the covers and inside the drains (pump OFF).
Scrub the seam/retaining plastic around stairs.
Scrub the walls at least daily.

Post pictures of the pool so we can see what we are dealing with.