SLAM almost done - CYA too low for Salt Water Pool? + Maintaining after the SLAM

[Visa1976]

Hi, still a newbie, but thanks to TFP...finally figuring out how to get my pool in good order. Started with CYA just above 90, so exchanged large amount of water and ended up with a CYA just under 40, got pH to 7.2 and started the SLAM. Seems I am nearing the end of the SLAM. I'm ready to add more salt to get it back to a good number, but am curious as to what my target CYA should be. I don't ever want to have to exchange that much water again, so a little gun-shy of raising the CYA too much -- but also want to make sure I don't lose so much FC as I try to settle in to the new normal.

Live in Dallas so it is piping hot here right now and my pool gets massive amounts of direct sun starting at about 9am until about 7pm. Asking for advice on more permanent CYA level and Salt level (assuming 3200) + how to determine the best FC relative to baseline target with endpoint CYA.

Also love to hear how to make sure I don't ever have to SLAM again - wondering about how to deal with pool parties and such (I have 6 kids of my own and we invite groups over often). Thanks in advance!

 

[jwiegley]

Hi, I’m just curious as to why you needed to SLAM this time?

 

[wireform]

I would advise you to not raise the CYA yet until absolutely sure the slam is over. My recommendation to you would be several days of each having a good not borderline OCLT to be sure the slam is over along with the 3 criteria rule. Then you can raise your CYA to 70-80 and use the hot side of the FC target per the poolmath chart. Salt level has nothing to do with the CYA but all to do with the cells recommended level to make it more efficient. CYA per the level for a SWCG pool to shield the produced chlorine.
Pool parties are always hard on the FC and that's where practical dosing of LC before the party would serve best. You can raise it upto the slam level per the CYA you have but I doubt you need that much so I'd say use poolmath to see how much LC per the % strength you have to raise it anywhere between 5 and 10 for good measure. After the party seeing what the actual loss is/was will tell you how much you'd need to add for future parties.

 

[Visa1976]

Hi, I’m just curious as to why you needed to SLAM this time?

Had an algae problem we couldn't get under control. The water wasn't terrible, but the algae was gaining ground. An over-night chlorine drop test was showing excessive loss of chlorine. So the SLAM was in order according to the standards used in TFP.

 

[Visa1976]

I would advise you to not raise the CYA yet until absolutely sure the slam is over. My recommendation to you would be several days of each having a good not borderline OCLT to be sure the slam is over along with the 3 criteria rule. Then you can raise your CYA to 70-80 and use the hot side of the FC target per the poolmath chart. Salt level has nothing to do with the CYA but all to do with the cells recommended level to make it more efficient. CYA per the level for a SWCG pool to shield the produced chlorine.
Pool parties are always hard on the FC and that's where practical dosing of LC before the party would serve best. You can raise it upto the slam level per the CYA you have but I doubt you need that much so I'd say use poolmath to see how much LC per the % strength you have to raise it anywhere between 5 and 10 for good measure. After the party seeing what the actual loss is/was will tell you how much you'd need to add for future parties.

Thanks! Last night's OCLT was better but still not there. Dropped 1.5 in FC. Going to keep at it. Just feels like it is taking a long time.

 

[Newdude]

Also love to hear how to make sure I don't ever have to SLAM again

The sun will burn off FC everyday, even in bad weather. Your mission is to replace it so that you never sniff minimum FC per your CYA level. It's a moving target and in April, 3ppm may last a week. In August it may last 3 hours mid day. Think of a bell curve across the season for UV loss. There's an occasional whoopsie week in there like a particularly high UV heatwave, but for the most part next week responds like last week.

I don't like the word minimum, it sounds way too ok-ish for me. Call it Swampville instead and you'll be inclined to give it the respect it deserves. 'Still above minimum' and 'Dancing on the outskirts of Swampville' have 2 distinct feels about them. I suggest the latter.

Dancing or even going below min doesn't guarantee algae, but each occurance is a chance and given enough chances, algae is all but guaranteed. YMMV if it's 2 or 9 chances that swamps you.

In the peak season, you may need to dose over target to achieve the mission. So be it. This is where folks go sideways because they see they are in target range and assume everything is great. Again, that might be enough in the early/late season and it might not in the peak season. PoolMath or the charts don't know your climate or point in the season, so you need to understand those, and how your testing time relates to the daily loss. 1 or 2 ppm above min is probably ok after the days loss, but probably isn't before the days loss. Start the day high and end free and clear above min.

SWG pools still swing, just not as much as LC pools. When you produce your FC is just as important in regards to the daily loss as how much FC you produce. For example, if you only produce at night, the pool will swing like a LC pool during the day and you need a larger window between the high and low FC. If you run 24/7, you'll dip a little during the mid day and make it up overnight.

 

[Visa1976]

The sun will burn off FC everyday, even in bad weather. Your mission is to replace it so that you never sniff minimum FC per your CYA level. It's a moving target and in April, 3ppm may last a week. In August it may last 3 hours mid day. Think of a bell curve across the season for UV loss. There's an occasional whoopsie week in there like a particularly high UV heatwave, but for the most part next week responds like last week.

I don't like the word minimum, it sounds way too ok-ish for me. Call it Swampville instead and you'll be inclined to give it the respect it deserves. 'Still above minimum' and 'Dancing on the outskirts of Swampville' have 2 distinct feels about them. I suggest the latter.

Dancing or even going below min doesn't guarantee algae, but each occurance is a chance and given enough chances, algae is all but guaranteed. YMMV if it's 2 or 9 chances that swamps you.

In the peak season, you may need to dose over target to achieve the mission. So be it. This is where folks go sideways because they see they are in target range and assume everything is great. Again, that might be enough in the early/late season and it might not in the peak season. PoolMath or the charts don't know your climate or point in the season, so you need to understand those, and how your testing time relates to the daily loss. 1 or 2 ppm above min is probably ok after the days loss, but probably isn't before the days loss. Start the day high and end free and clear above min.

SWG pools still swing, just not as much as LC pools. When you produce your FC is just as important in regards to the daily loss as how much FC you produce. For example, if you only produce at night, the pool will swing like a LC pool during the day and you need a larger window between the high and low FC. If you run 24/7, you'll dip a little during the mid day and make it up overnight.

Super helpful! Do you also suggest 70 CYA as a minimum for me? I see the range starting at 60. Do you also suggest running your SWG 24/7 at a lower percentage or just running it through the day for as long as is necessary at a higher percentage? How far above baseline FC do you try to max out at during summer months (I know you are in a different climate, but just trying to get a feel for the variances)?

 

[Newdude]

Do you also suggest 70 CYA as a minimum for me?

You'll road test that and report back.

60 to 90 is the accepted SWG range based on climate. 60 usually works for me up north but you're 53 miles north of Heck, and have much worse UV.

Do you also suggest running your SWG 24/7 at a lower percentage or just running it through the day for as long as is necessary at a higher percentage?

Personal preference. I'm on team 24/7. When you are skimming is just as important as for how long. If the floating crud has 12+ hours to get waterlogged and sink, it needs to be vac'd off the floor. Or you only run at night but it's particularly windy during the day today. It's going to make more work for you.

24/7 will likely never make you wonder if you're filtering enough. It should be well covered by default.

24/7 also keeps the FC topped off around the clock so if a big storm hits overnight, not only are you covered, but you're mixing that 0 FC rain water immediately so it doesn't have time to fester.

There is a cost adding 12 ir so more runtime hours to the electric bill, but at low RPM it's $10 or so a month more over what you needed with part time operation. To some it's worth every penny, others like their literal pennies too much.

How far above baseline FC do you try to max out at during summer months

I let the SWG match the high UV loss days of that part of the season and accept it will over produce on the cloudy days. I step in when FC drifts beyond 8 to 12. I might run a little higher in the insane part of the TX season if I was by you.

 

[dereksanders]

In my neck of the woods I have my CYA at 80 and it worked splendidly. I’ve been running my SWCG anywhere from 3-6 hours depending on conditions, starting at 5:00am, to take my level at or near 9. I’ve never lost more than 4 in any day.