Update: OCLT Results and Next Steps. Question Re: OCLT

[ald2002]

Pool is not holding chlorine. OCLT is my next step. First time performing and need to “phone” a friend. I understand I need to turn off my SWG before the night and am test. Is it best to keep the pump running or turn off during the testing period? Thanks.

 

[duraleigh]

In theory, it makes no difference but it will keep you pool well mixed for the early AM test so I would let it run.

Good luck with your test...........show us the results.

 

[ald2002]

In theory, it makes no difference but it will keep you pool well mixed for the early AM test so I would let it run.

Good luck with your test...........show us the results.

Thank you! Another likely silly question. My pool school was so short and I do not remember how to shut down my SWG. Can I simply set IntelliChlor output to 0%? I appreciate ya’ll and I will post results in the am.

 

[Texas Splash]

Can I simply set IntelliChlor output to 0%?

That should work fine.

 

[ald2002]

That should work fine.

Thank you. Fingers crossed….

 

[ald2002]

Results are in please below - I passed. Also added most recent test results. I need help on next steps, please.

OCLT Results
Evening FC - 4/CC -0
Morning FC 3/CC-0

Test Results as of 7.11 am
FC - 1
CC - 0
pH - 7.5
TA - 100
CH - 350
CYA - 40 (too low for SWG)
Salt - 3000 ppm
Temp 83

Last week pool was sparkling blue and turned light green quickly (I posted about this). Through the help of this forum iron was suspected since I had a brown area on my skimmer which was removed with vitamin C. My pool maintenance crew arrived to clean my filters and salt cell. My pool guy offered to help. Turned green a few minutes before he arrived.

To my ignorance, I am still learning, I allowed him to add A+ Stain Remover which I think is AA. He called it vitamin C. They left me with Regal “Metal Out” which I used the next day. I should have used a recommended sequestrant from TFP - lesson learned. Mistakes are the best way to learn. The pool cleared up quickly.

Is it possible AA is neutralizing the chlorine? AA was added on 7.6 and sequestrate added on 7.7.

My CYA is low. Is it possible this is the root cause? Note, last year CYA was high and I had to drain my pool. Kept CYA at 40 last summer and chlorine held at 5 ppm with output at 30% with no issues.

Water is clear. I have SWG output up to 70%. Will test during the day and add LC as needed to mitigate the risk of algae.

Please suggest next steps. Thank you.

 

[Texas Splash]

Is it possible AA is neutralizing the chlorine?

Yes, although by now you would think it should all be gone. Here's what I would do now:
1 - Increase the FC to about 6-7 ppm with liquid chlorine. Do that ASAP. It's odd you passed the OCLT but then lost 2 ppm of FC so quickly, so I'm not so sure you're out of the (algae) woods yet. Keep some liquid chlorine available for a few days and be sure the FC remains nice and strong. Never let it fall below 3 ppm.
2 - Your CYA is definitely low and needs to be increased. I would feel better knowing all algae concerns are behind you before increasing, but I would take the CYA to at least 60 for now. It's slightly below the recommendation, but should help the SWG and be manageable if you discover in the next day or two a SLAM Process is still required.

Everything else is fine for now, just watch that FC level. If it drops quickly again, you might consider one more OCLT just to be sure.

 

[Texas Splash]

Once you are 100% sure the FC is holding and there are no further signs of algae, then go ahead an increase the CYA to 70. That additional CYA makes a big difference in SWG performance.

 

[ald2002]

Yes, although by now you would think it should all be gone. Here's what I would do now:
1 - Increase the FC to about 6-7 ppm with liquid chlorine. Do that ASAP. It's odd you passed the OCLT but then lost 2 ppm of FC so quickly, so I'm not so sure you're out of the (algae) woods yet. Keep some liquid chlorine available for a few days and be sure the FC remains nice and strong. Never let it fall below 3 ppm.
2 - Your CYA is definitely low and needs to be increased. I would feel better knowing all algae concerns are behind you before increasing, but I would take the CYA to at least 60 for now. It's slightly below the recommendation, but should help the SWG and be manageable if you discover in the next day or two a SLAM Process is still required.

Everything else is fine for now, just watch that FC level. If it drops quickly again, you might consider one more OCLT just to be sure.

Is it ok to test via OTO throughout the day? For OCLT I use FAS-DPD. I will hold on CYA. THANK YOU!

My pool is a stubborn lol.

This is strange. I did notice some brown around the light. Looks like iron. Will dive in later and see if I can remove with vitamin C.

 

[ald2002]

Once you are 100% sure the FC is holding and there are no further signs of algae, then go ahead an increase the CYA to 70. That additional CYA makes a big difference in SWG performance.

Copy. Thanks.

 

[Texas Splash]

Is it ok to test via OTO throughout the day?

Sure. But what I would recommend is to practice with it and the FAS-DPD (powder & drops) so you can establish a good visual comparison between colors. If the FAS-DPD shows an FC of 6, 7, or 8, you'll know what that OTO color shade should be. Obviously if it's low the shade will be very light.

 

[ald2002]

Sure. But what I would recommend is to practice with it and the FAS-DPD (powder & drops) so you can establish a good visual comparison between colors. If the FAS-DPD shows an FC of 6, 7, or 8, you'll know what that OTO color shade should be. Obviously if it's low the shade will be very light.

Agree. Just tested with FAS-DPD. Still at 3ppm. Going to add LC now. How often do you suggest I test? I’ve been testing a lot.

 

[Texas Splash]

How often do you suggest I test? I’ve been testing a lot.

Normally once a day is fine when the chemistry is stable. Since yours has been a little up & down recently, perhaps try to check once in the morning and once later in the evening. Once you feel confident the FC is remaining stable, cut back to once per day.

 

[ald2002]

It’s me again! I inspected every possible nook of my pool. Noticed part of my light is no longer flush against the pool wall. See photos. This means there is space between the light and pool wall. Is this a possible place for algae to hide? Photos aren’t the best. I see a bit of brown stuff but hard to tell what it is. Sorry to be obsessive but the high chlorine load is driving me nuts.

 

[Texas Splash]

I can't tell from the pic, is that one of those halogen lights with a niche behind it, or it that an LED type? There might be a niche since that one screw seems to be holding it in. Definitely a potential hiding place for algae. If you do pull it out, make sure power is OFF first at the breaker that supplies power.

 

[ald2002]

I can't tell from the pic, is that one of those halogen lights with a niche behind it, or it that an LED type? There might be a niche since that one screw seems to be holding it in. Definitely a potential hiding place for algae. If you do pull it out, make sure power is OFF first at the breaker that supplies power.

LED light. Awful photo, sorry. I am not brave enough to pull the light out. I’ll need to get help with that. Performed another OCLT. Also learned my pool volume is off by nearly 2k. No wonder I had problems balancing.

 

[Texas Splash]

LED light. Awful photo, sorry. I am not brave enough to pull the light out.

Normally we don't bother trying to remove LED lights, but yours seems a bit different to me. Let's ask @1poolman1 if this light is worth removing to inspect for algae behind it. We don't' want to cause more problems.

 

[ald2002]

Normally we don't bother trying to remove LED lights, but yours seems a bit different to me. Let's ask @1poolman1 if this light is worth removing to inspect for algae behind it. We don't' want to cause more problems.

Thank you

 

[1poolman1]

The light, probably, was never completely flush with the pool surface. You're just now noticing the gap. There is always water behind a light in a pool, even the ones that thread into a 1.5" fitting. The light ring appears to be a Pentair Amerilite with a conversion kit in it or, maybe Ameribrite. Can algae hide behind it? Likely. Would there be enough to cause a huge chlorine demand? This is where I differ with some of what has been said here. There is water back there, it is needed to cool the fixture, and yes, LED fixtures do get hot. Lots of chemical reaction happen faster in warm water and that may account for the brown stain you saw. Does the algae there cause an issue, maybe, but there is very little, if any circulation behind the light to get it out of the niche.

You could loosen the screw, take a garden hose and flush behind it to clean the niche out, they usually have a lot of dirt in them, and algae does like dirt. It is a sealed unit, won't hurt you and not that hard to replace if you take the screw all the way out. Its about 1 1/4" long so you can unscrew enough to get a good flow of water back there with a hose without completely removing it.

You could then, with the light loose and away from the wall a bit further than it is now, pour a jug of chlorine, or a handful of chlorine powder, right down the wall over the niche. Some will get in behind the light.

 

[ald2002]

The light, probably, was never completely flush with the pool surface. You're just now noticing the gap. There is always water behind a light in a pool, even the ones that thread into a 1.5" fitting. The light ring appears to be a Pentair Amerilite with a conversion kit in it or, maybe Ameribrite. Can algae hide behind it? Likely. Would there be enough to cause a huge chlorine demand? This is where I differ with some of what has been said here. There is water back there, it is needed to cool the fixture, and yes, LED fixtures do get hot. Lots of chemical reaction happen faster in warm water and that may account for the brown stain you saw. Does the algae there cause an issue, maybe, but there is very little, if any circulation behind the light to get it out of the niche.

You could loosen the screw, take a garden hose and flush behind it to clean the niche out, they usually have a lot of dirt in them, and algae does like dirt. It is a sealed unit, won't hurt you and not that hard to replace if you take the screw all the way out. Its about 1 1/4" long so you can unscrew enough to get a good flow of water back there with a hose without completely removing it.

You could then, with the light loose and away from the wall a bit further than it is now, pour a jug of chlorine, or a handful of chlorine powder, right down the wall over the niche. Some will get in behind the light.

Thank you!