Drain first or SLAM

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pgjohnson

Well-known member
Jun 21, 2015
102
Australia
Hi,

So failed the OCLT test and realize I need to SLAM.

A few months back (June) I did an ascorbic acid treatment which worked well. Now just wondering as my Total Copper measured around 0.4 as to earlier in the year around 0.2 so wondering if I should replace some water first before I SLAM else that suspension could cause staining again?
I think (not clearly visible) I can see what could be staining starting again although could be my imagination/poor eye sight s its very light and barely visible.

Basically just wanted to know what the best attack here is, drain to remove some copper or just go ahead with a SLAM. Is copper the same as the source of the iron stains that are now sequestered in suspension or is copper unrelated?

Thanks
 
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If you are sure you have an elevated copper level, and the staining could be from that copper, I would be inclined to get it out first by using a sequestrant to get it into suspension as much as possible then changing water. It's imperative you remove the copper or else you face the possibility of having incredibly difficult stains to remove later post-SLAM.

But here's what is odd. An AA treatment would work for iron, not copper. So you have to be sure of what you are dealing with here. It's not clear in this thread where these metals are coming from, so if you have more details on the source that could be helpful.
 
I don't actually think the staining is from copper. Only reason I mention copper is pool shop test (yes I know I can't trust but only option at this stage as unable to test myself) changed from 0.2 to 0.4. And definitely not reliable as measured again with them today and now 0.1 (said due to ph down from 7.9 to 7.2 - but again I know I should not rely on pool shop advice). After reading on this site was concerned at 0.4 could cause issues if I SLAM.

AA treatment was done on iron stains (vitamin C test) and was successful, maybe a product I used introduced the copper? So definitely think new stains could be iron, copper was only mentioned due to tests. And as mentioned not sure I can even see stains, a person looking at my pool would probably not see them.

Reason I need to do this is chlorinator is failing and OCLT failed (6.5 down to 4). Other than that pool is crystal clear and looks like nothing wrong with it :)

Thanks
 
Based on your update, I would focus on the potential for iron and of course algae. Normally we recommend to do the SLAM first to take algae out of the equation and be able to see clearly across the pool surfaces during the AA. Naturally it's quite possible the SLAM Process would aggravate any iron in the water, at which point we recommend trying to mechanically capture the iron at this point via polyfill. Once the SLAM is complete and you've attempted to filter out iron, owners are left with the choice of leaving the water as-is (if the polyfill removed enough iron) or doing the AA, dumping & exchanging for new water.

But here's something to think about. I believe you are still in the middle of your swim season down-under correct? So you know part of the AA process is letting the FC fall to zero for a short period. When you do that in warm water, there's an increased potential for algae. After you complete the SLAM, you could introduce the algae later during the AA when you drop the FC level. Even if you use a non-copper algaecide it's a risk, so keep that in mind. I like to encourage members over here to do their AA at the beginning or very end of the swim season when the water is cold to lower the chance of algae, but sometimes waiting isn't an option. Just be aware of the possibilities and go with what works for you. Hope that helps.
 
I am going to attempt to SLAM in the next day or so but think my CYA level is around 20 - 30.

1. Is it best to add some stabiliser to get this just above 30 or can I start the slam process at the same time as adding stabiliser using the sock method?
  • my pump is in for repair and will be back tomorrow, can I add stabilser by letting sock float around with no pump running?
2. When you do the SLAM, one of the tests is the OCLT, do you do this multiple nights. So lets say you pass OCLT test on night 3, on day 4 do you still keep at SLAM levels and test again night 4?

Thanks
 
pgjohnson said:
Is it best to add some stabiliser to get this just above 30 or can I start the slam process at the same time as adding stabiliser using the sock method?
Click to expand...
If you believe the CYA is slightly low, you can add the stabilizer during the SLAM.

pgjohnson said:
When you do the SLAM, one of the tests is the OCLT, do you do this multiple nights. So lets say you pass OCLT test on night 3, on day 4 do you still keep at SLAM levels and test again night 4?
Click to expand...
The OCLT is usually the last test of the 3 criteria to be performed. Once you pass, you're done.
 
So currently doing a SLAM, 2nd day in.
From reading on this site it seems like adding too much choline makes the levels drop faster? SLAM level is 16 but have sometimes been pushing up to 20 but it drops very quick down to around 14/15 after 2 hours. OCLT last night was 2.

Should it drop this quickly if I go higher. Pool is extremely clear and has been for about 3 weeks but chlorinator was battling and chlorine had fallen to 0 at one stage.

Feel like I am missing something? OCLTs in the past week or so hovered around 1.5 loss.

Yesterday at one stage it did not move after 2 hours, today seems to be dropping faster.

OCLT last night: 16.5 - 14.5

1. What should the level be on at night to start OCLT, or even if have extra chlorine say like 20 should stay at 20? Will it only hold at SLAM level?
2. Is the test accurate in the morning if pump is not running all night, I am unable to run at night due to noise.

Seemed to hold from 5pm to 7pm, mostly sun gone. Will do overnight test.

Thanks
 
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A few things to address in your last post:
1 - The starting OCLT level is based on your CYA and the required FC-SLAM level as noted on the FC/CYA Levels. So if your CYA is 30, the FC should be 12. If the CYA is 40, the FC should be at 16. If your CYA is 50, the FC should be 20. The intent is to "try" and maintain that proper FC level throughout the day and up until you start the OCLT at night before going to bed.
2 - Ideally, the pump should be running 24/7 until the SLAM is complete. If you must turn off the pump, be sure to turn it back on at least 30 min before taking the second (morning) water sample for the OCLT. Remember, you have to do this before the sun hits the water.

In addition, you mentioned something about your chlorinator. Keep in mind that during the SLAM Process, the salt cell should be off and you should be using liquid chlorine to maintain that elevated FC level. No chllorinating device should be on during the Overnight Chlorine Loss Test either. If you are experiencing a large drop in FC, it can only be a few things:
a. Inconsistent FC test results
b. Too low of CYA resulting in rapid FC loss during the day. But if your CYA is 30-50, it's fine.
c. Algae is still somewhere in the pool and not discovered. This one is much more common than you might think, so we may need to come back to this one.

If you have any other questions let us know.
 
Yeah, pump running is the issue, sun up at 5am and unable to start pump until 7am.
CYA around 30/40
Sun down around 6pm

Test at 7pm - 20.5
Pump off at 7:30pm
Test at 9pm - 19

Might never be able to get accurate results with not being able to run pump. Have not ever seen signs of algae and pool has been clear for weeks even after chlorine dropping to 0 and CYA around 20/30. Have been having drops around 1.5 in the past few weeks consistently.
 
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Algae is not visible until it is. My water was clear but when I removed my ladder and took it apart I found algae throughout the apparatus. That was the culprit causing my OCLT failures. Once cleaned and reinstalled I passed OCLT several times before calling the SLAM complete.
 
I have a VSP pump, just old and starting to make a noise, and also not really a solution at this point in time.

Sun rise around 4:45am.
4:50am - 17
Pump switched on at 5am
6:00am - 17
8:00am - 15.5

No ladders or anything, just return pipes and some non used return pipes for heating (no heating currently in pool) and 2 LED lights.

No sure (so won't) remove hydrostatic valve lid and check for algae in there. Also have covers for return valves? Dived in and checked covers (3 - 2 for unused heater return valves and 1 for hydrostatic valve), would all need to be removed via screwdriver (except hydrostatic valve, no idea, don't see screws) , don't think I will attempt that at this stage. Can see slight dirt at bottom of hydrostatic valve pit, tries to vacuum out but difficult.
 
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Also say I am out with my CYA reading. So if I am raising my SLAM too high (20 instead of 16) I have read from the forum that FC drops much quicker above SLAM.

The question is, if my FC is above SLAM level, is there any way that can drop in an OCLT?
 
pgjohnson said:
if my FC is above SLAM level, is there any way that can drop in an OCLT?
Click to expand...
If the FC was extremely high for the CYA, it is possible. But only being 3-4 ppm over shouldn't be a factor.

The return jet eyelets shouldn't be an issue. A drain cover can sometimes hide organics because the water movement isn't quite as strong, so at some point you might need to check. With nothing else in the pool (no light niche, ladder, seams, etc) there's not much else to check. Are you using a speed stir device to assist with testing?
 
No speed stir device. I feel my CYA is around 30/40 but thought just up to slam level 20 to see if helps for a day. Today will keep around 16.
Can see some dirt (not too much) in hydrostatic valve drain but no idea how to get cover off (not brave enough to try remove yet), dived in and tried to vacuum some out but not much luck.

Over past 2 days, had a period of 4/5 hours with no drop around 16 on day 1 and 1 period of 2 hours no drop around 20 on day 2.

OCLT day 1/2: 2 ppm (16.5 - 14.5)
OCLT day 2/3: 2 ppm (19 - 17) - 20.5 to 19 from 7pm (dark from 6pm) to 9pm, 19 to 17 from 9pm to 4:50am next day (SLAM around 20 for day 2)

Should the drops in ppm be getting less each day or can they remain the same for many days and then only get better.
 
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Drain cover and drain entrances are notorious for extending SLAMs. I'd figure out a way to get the covers off and scrub the drains.

Do you have an autofill? Scrub it.
Have you checked the weir doors for algae?
 

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