Can't keep my pool clean this summer!

[PoolStored]

Follow the slam process…link—>SLAM Process

 

[PoolStored]

With a CYA of 100, Perform #8 here to get a more accurate CYA.

CYA - Cyanuric Acid Test​

You likely need to replace a large % of your water. See No "Drain Water Exchange" You need to get your CYA down to at least 60. Water exchange is 1:1...so if your CYA is 120, you need to replace 50% of your water to get to 60.

Draining - Further Reading​

After you replace water, follow the SLAM process to clear the pool. Link-->SLAM Process

 

[kennyjg44]

Thanks for the input! I will retest the CYA.

For what it's worth, my pool has been staying mostly clear as long as I vac / brush every few days (I usually don't have to do it this often). I have found in years past that chlorine and CYA burn up quickly with the sun, is that not the case?

 

[kennyjg44]

I ran the CYA #8 test, came out to about the same (50*2). So no change.

I'm just pressed to start draining my pool, though. For the most part, it looks and feels clean enough. The water isny crystal clear, and after a day or 2, I'll get dirt/algae growth forming on walls and bottoms. Shock, scrub, vac, repeat.
Chlorine level very low again this morning, despite the high CYA, which I thought was supposed to keep chlorine in the pool...

 

[PoolStored]

To clear the pool of algae, you need to follow the slam process....Link-->SLAM Process

You can do it at CYA of 100, but it will take an enormous amount of chlorine.

It would be better to replace 40% of your pool water to reduce CYA to 60.

 

[kennyjg44]

To clear the pool of algae, you need to follow the slam process....Link-->SLAM Process

You can do it at CYA of 100, but it will take an enormous amount of chlorine.

It would be better to replace 40% of your pool water to reduce CYA to 60.

Is there an explanation as to why I'm not holding chlorine?

 

[PoolStored]

Is there an explanation as to why I'm not holding chlorine?

Algae is consuming it. You need to use the SLAM process to kill the algae, so your FC can hold.

 

[kennyjg44]

Algae is consuming it. You need to use the SLAM process to kill the algae, so your FC can hold.

Thanks for that, makes sense. Then the obvious question is, why am I getting so much algae? It's my SWG not keeping up?

I've looked over the SLAM process. I will try and see how I can fit it into my schedule.

Somewhat unrelated, is there any guidance here on filter pressure and / or backwashing? My pressure has raised consistently since my first summer, almost at 30 now. It never drops, even after a backwash (which I only do monthly).

 

[PoolStored]

Then the obvious question is, why am I getting so much algae?

You need to maintain your FC based on your CYA. Answer here: Link-->FC/CYA Levels

It's my SWG not keeping up?

Post up the make and model # of the controller and the SWCG cell.

filter pressure and / or backwashing? My pressure has raised consistently since my first summer, almost at 30 now.

Does your gauge go to 0 when you turn the pump off? If not, bad gauge. Might be worth a replacement anyway.
Backwash. Run the pump on high, not clean pressure. Test your pressure on high regularly, when it rises 25%, backwash again.

 

[Deb04]

Thanks for that, makes sense. Then the obvious question is, why am I getting so much algae? It's my SWG not keeping up?

Because your CYA is so high. Your CYA is binding up so much of your FC that it can't do the job of killing algae. That's why it would be so helpful to replace 40% of your water to get your CYA down to 60.

 

[SJPoe]

Is there an explanation as to why I'm not holding chlorine?

Your FC is being consumed by UV (the sun) and by killing Algae.

Think of the CYA more like a gatekeeper (the chemists here will be screaming inside their heads now) - the more CYA you have, the less FC molecules get to go attack stuff....which is why as long as you keep the FC/CYA ratio in balance, you don't suffer all the side-effects of high Chlorine. The FC is there, it's just not allowed out-to-play, and just sort of sits there, waiting

Now, during an extended period, eventually enough of the FC gets past the gatekeeper and dies killing the Algae, or by getting bombarded with UV - and you end up with no FC. With less CYA, this happens quicker, as more FC gets past the gatekeeper. If there is enough FC getting past the CYA, then the Algae never gets a chance to grow, and your pool stays shiny and clean. If there isn't enough, then the Algae can slowly take hold, as it's growing quicker than the FC is available to kill it, regardless of how much is 'behind' the CYA.

To kill off the established Algae, we need a lot of FC to get past the CYA, for an extended period of time. So, we can either put a LOT of FC in the pool, or we can reduce the CYA and let more of the FC past in a given period. Its a lot cheaper (usually) to replace the water to drop the CYA concentration, than to hold an FC level very very high for an extended period.

 

[kennyjg44]

Your FC is being consumed by UV (the sun) and by killing Algae.

Think of the CYA more like a gatekeeper (the chemists here will be screaming inside their heads now) - the more CYA you have, the less FC molecules get to go attack stuff....which is why as long as you keep the FC/CYA ratio in balance, you don't suffer all the side-effects of high Chlorine. The FC is there, it's just not allowed out-to-play, and just sort of sits there, waiting

Now, during an extended period, eventually enough of the FC gets past the gatekeeper and dies killing the Algae, or by getting bombarded with UV - and you end up with no FC. With less CYA, this happens quicker, as more FC gets past the gatekeeper. If there is enough FC getting past the CYA, then the Algae never gets a chance to grow, and your pool stays shiny and clean. If there isn't enough, then the Algae can slowly take hold, as it's growing quicker than the FC is available to kill it, regardless of how much is 'behind' the CYA.

To kill off the established Algae, we need a lot of FC to get past the CYA, for an extended period of time. So, we can either put a LOT of FC in the pool, or we can reduce the CYA and let more of the FC past in a given period. Its a lot cheaper (usually) to replace the water to drop the CYA concentration, than to hold an FC level very very high for an extended period.

Thanks for this unbelievable explanation - makes a ton of sense (sorry chemists!)

After all is said and done, sounds like I need to find the right FC / CYA balance to allow for a clean pool but not over-chlorinated - how is that done?

 

[kennyjg44]

Post up the make and model # of the controller and the SWCG cell.

AutoPilot Pool Pilot Digital Nano+

 

[kennyjg44]

Does your gauge go to 0 when you turn the pump off? If not, bad gauge. Might be worth a replacement anyway.
Backwash. Run the pump on high, not clean pressure. Test your pressure on high regularly, when it rises 25%, backwash again.

My gauge does set back down to 0 when the pump is off, but I will try to swap it anyway.

To my knowledge, my pump doesn't have any settings to run on "high", nor do I know how to test the pressure (just the gauge).

 

[PoolStored]

So you have a single speed pump?
Use the gauge, sorry. I used test to mean, run the pump on high and read the pressure.

Your salt cell creates 1.06 lb/day of chlorine, which would add 8.5FC if you ran it for 24 hours at 100% If you clear the pool, it should be able to sanitize your pool. It should be OFF for slam.

 

[kennyjg44]

So you have a single speed pump?
Use the gauge, sorry. I used test to mean, run the pump on high and read the pressure.

Your salt cell creates 1.06 lb/day of chlorine, which would add 8.5FC if you ran it for 24 hours at 100% If you clear the pool, it should be able to sanitize your pool. It should be OFF for slam.

Understood! My pressure gauge is reading 28 consistently for most of this summer; started the season closer to 20. When the pool was first installed, it ran at about 8, but haven't been close to that value in years, no matter how many backwashes I've done.

At the pool company's suggestion, I only run the filter/pump ~8 hrs a day, and I'm pretty sure that the SWG is not set at 100% (they set it all up).

 

[SJPoe]

After all is said and done, sounds like I need to find the right FC / CYA balance to allow for a clean pool but not over-chlorinated - how is that done?

Exactly. Once the SLAM is complete (you've nuked all the Algae to the point it is undetectable), then you just need to maintain the correct FC-CYA balance to ensure it never comes back.

If only someone had worked that out for you already

The Free Chlorine and Cyanuric Acid Relationship

Managing your cyanuric acid and Free Chlorine levels is key to stabilizing your pool. Learn how these two items affect each other.

www.troublefreepool.com

I'm not kidding when I tell you I have not 'shocked' my pool in almost 3 years using the TFP system. You tell me how it looks...

 

[kennyjg44]

Looks unbelievable! My pool looks like that every now and then LOL! I did read the FC/CYA relationship article; makes some sense, but I guess I'll worry about that when I get my CYA levels under control.

I'm guessing my first few years of pool ownership haven't been as great as I feel the water has looked, as this year has proven an issue. I do think I've overused CYA in past years because there was never any FC in the pool....

 

[kennyjg44]

Tried to start the water exchange processv after work today. I feel like someone's playing a joke on me. If my calculations are accurate, I'm looking at almost 24 hrs of water exchange to do about 50%

 

[PoolStored]

Yep. Took me 36….