Crystal clear, no chlorine

MarkL-TX

Member
Aug 21, 2020
7
College Station, TX
I have been using the great info on this site to put together a plan to get my pool back (from nature, pool store chemicals, whatever). Doing what the pool installer/store said worked great, until it didn't. Now I have algae (finally!) and a chemistry that reflects things that I now know should have stayed out of the pool (and some chemicals at home that will never see the pool to be dealt with somehow). I did realize a while back that I couldn't just use trichlor all the time like I was told to, so CYA is not as bad as it could be. It is TX, so high-ish CYA may not be so bad.

Last night: 0.2 FC, 0 CC; pH 7.3 (just lowered from 7.5); CH 230, CA 90, CYA 60. Per recent pool company test, Cu is down to 0.2 ppm, phosphates >3000 (they don't believe their own device here, but is consistent with history.

I was planning to SLAM starting Sat evening, so I added ~5 ppm chlorine (48 oz 12.5% bleach).

Key backstory: pool has not held chlorine overnight since at least late June. There was a period of insufficient maintenance before that, and 2 weeks of pool on autopilot. The pool looked and smelled great at all times, which contributed to the neglect (there were squeakier wheels). In late June, 1 lb of Cal-hypo (10 ppm) stained the bottom of the pool. The stain appeared faster than the brush could come out, but disappeared on its own (probably within hours). Eventually, this was traced to Cu oxidation. Three doses of Metal Out later (don't judge, being this stupid got me here to get smarter) I had lower Cu and lots of Phosphates. Bunches of the Cu came out in filter cleanings, but the Cu rebounded to >0.4, but now with kilo-Phosphates. It de-stained the pool, though. After a brief interlude with a phosphate remover the pool store recommended, we decided to stop playing the old-lady-who-swallowed-a-spider game and come up with a real plan.

Fast forward: I still can't drop Ca-hypo in (must be Cu in plaster now?), but I can pre-dissolve it. CuLater seemed to help with the Cu without additives. The pool has remained clear, with visible surface algae starting to appear in the last week or so. Having researched Cu and Phosphates, I had decided that chlorine was 'safe'--it still didn't last overnight, but visible algae was absent, and bleach didn't cause stains. I didn't go there when Cu was so high there was instant staining, since I wasn't sure if that wasn't catalytically destroying the Cl.

Today: After seeing some algae last night and adding Cl and brushing, I saw more in the morning; 0FC/0CC. Bad. I added 10 ppm Cl via Cal-hypo (pre-mixing). The water got cloudier. In 15 minutes, I had 1 FC, 1.5 CC (FAS-DPD). Worse. Much worse. I had assumed the pool was usable (specifically, tomorrow) with Cl addition, even without overnight survival. Maybe you'd argue with that; but if the Cl doesn't last 15 minutes there's no argument to be had. 76 ppm of Cl addition later (in stages, of course, with tests in between and a couple brushings), I may have slowed the loss rate, but not much. I pursued this less aggressively during mid-day (work + UV) but will get back to it soon. It has been variably cloudy; distinctly greenish after a couple Cl additions (I imagine that's the Cu). Update: It lost 90% of added Cl within 90 minutes after last addition; will go to 30 minute cycle this evening.

Finally: the pool installer included an O3 system; the light works. I'm guessing the Cu oxidation means the O3 generation is not working or at least not accomplishing anything. So, this is likely not relevant, but who knows?

My best guess is that the best way to get the pool to hold Cl is to add Cl until it relents, and then SLAM. So, I am going down this path earlier than planned, as best I can at the moment. I have 90 ppm-equivalent in bleach on hand, plus 10 ppm of cal-hypo (the pool can stand a bit more Ca, but not enough to finish this process). Looks like I'll need more.

If there are any red flags and this Cl is just going to waste, please say so. Otherwise, the appearance of algae sure makes me think I should treat this like a crystal-clear 'green swamp'--there's algae/stuff hiding somewhere, and chlorine will win, with persistence. (It does get significant debris input, oak & dust; is skimmed 2x/day and we recently upgraded suction-side cleaner to robot; skimmer baskets & leaf traps emptied, filters cleaned recently.)
 

Mdragger88

Bronze Supporter
Jun 1, 2018
1,628
Hernando, Ms
You have 2 choices:
1: Drain& refill about 40-50% to lower copper, cya & whatever else u have added then start option 2 👇

2: Begin SLAM Process now- no time like the present- follow the FC/CYA Chart
Frequent fc testing & liquid chlorine additions to maintain slam level of 26ppm. As often as possible but not more than once per hour. It will require large amounts of liquid chlorine due to the high cya level but it’s definitely doable
If you’re not raising to slam level every time you are wasting liquid chlorine .
After u pass all 3 end of slam criteria
Then deal with the copper & sequesterants👇
 

MarkL-TX

Member
Aug 21, 2020
7
College Station, TX
I had seriously considered #1. But on a septic system, with drainage to neighbors yards, a slow water replacement seems better.

I'm not sure I can believe the magic number really matters much at this stage--70-80% of FC is lost in 30 minutes, it spend most of its time <5. But no matter, #2 is what I did (well, in progress). Raised to 26, 4 times since my last post, about hourly since I could start. Nonetheless, efficiency will have to be compromised tomorrow. There was a reason I wanted to wait. Oh well. "26" is theoretical, of course, since FC doesn't last long enough to be uniform. Totaled 95 ppm-equivalent across 4 additions, never tested above 4 FC after an hour.
 

MarkL-TX

Member
Aug 21, 2020
7
College Station, TX
Quick update Saturday: needed 90% of shock level added again last night at 10:20. My wife got up to add 80% of shock level without a measurement, since it has been losing 90% in an hour.

It was at 1 ppm FC at 7 AM; I added 25. Then, the pool turned a corner. 10.5 FC at 8 AM; I topped it off. >25 ppm FC at 9:15 (I stopped adding drops); no addition. 24 ppm at 10:15; no addition. At this point the pool needed to go several hours on its own--but I felt way better with hours of slow loss of FC rather than hours when it lost 90% in the first hour. I hear that it saturated a test strip that purports to go to 10 ppm at 3 PM, so it is at least sanitary and maybe shocking.

The plan is to maintain shock through tomorrow and attempt OCLT if things are still looking good. Maybe test tonight if the numbers look really good through the evening after I get back to real tests. The slight cloudiness is gone and the pool is quite clear again.
 

Texas Splash

Mod Squad
TFP Expert
LifeTime Supporter
The plan is to maintain shock through tomorrow and attempt OCLT if things are still looking good. Maybe test tonight if the numbers look really good through the evening after I get back to real tests. The slight cloudiness is gone and the pool is quite clear again.
Good you are seeing improvement. :goodjob: But don't rush the SLAM Process and lose your progress. Save the Overnight Chlorine Loss Test for the last step and go to it only after the water is crystal clear. Maintain the proper SLAM-FC level for your current CYA (see FC/CYA Chart) and inspect/brush every inch of that pool. Something caused that severe FC loss and you need to make sure you find it. If you have a niche behind the light, pull the light. Hollow steps or a ladder? Main drain cover, look underneath. Leave nothing to chance so the chlorine can do its job. Good luck!
 
  • Like
Reactions: Mdragger88

MarkL-TX

Member
Aug 21, 2020
7
College Station, TX
We've kept it at 20+ (targeting 27 with each addition, with SLAM level of 24) last night, and overnight, and every 3 hours today. Given how hard it was to get here, and how easy it is to stay here, we're just going to hang at this level for a bit. Our previous blind spot was the overflow -- not connected to the pool yesterday due to low water; but since it does connect, it needed to be hit.
 

Newdude

Gold Supporter
TFP Guide
Jun 16, 2019
5,469
NY
Given how hard it was to get here, and how easy it is to stay here, we're just going to hang at this level for a bit
Many people hold the SLAM for an extra day or two for exactly the reason you stated. A day or two in the easy stage could prevent many days back at the hard stage. It’s a no brainer. Keep up the great job !!
 

Katodude

Silver Supporter
Aug 22, 2017
1,244
West Palm Beach/Florida
You may also just want to run FC a little hot for a few weeks after the SLAM. Not full SLAM level but 15% - 20% of your CYA. The few times I have had to do a SLAM this seems to help me. When I want algae dead, I want it good and dead.
 

MarkL-TX

Member
Aug 21, 2020
7
College Station, TX
It's now two mornings in a row, waking up at or very near SLAM levels. We've lost some overnight, but can only estimate based on the last addition, since we haven't formally tried the test yet. My wife has a new reason to stay at SLAM levels. Apparently mosquitoes can't taste chlorine (guessing). They seem to land and drink until they die. She's pondering the overnight mosquito loss test.

I think easing back to normal with a slightly elevated period sounds like a great idea, just as insurance.
 
  • Like
Reactions: Mdragger88

MarkL-TX

Member
Aug 21, 2020
7
College Station, TX
We lost only ~0.5 ppm last night, with trace CC and a clear pool. So, yay. The test was not planned--I had added enough Cl through the day to keep up with UV (and wind) losses. So, I didn't need to add after measuring last night. And the night was calm, with little influx of organics. We'll proceed with another 24 h at SLAM levels, then drift down to 15% of CYA for a few days. That'll get us through the storms before we start to establish a new baseline per the FC/CYA chart.