Sanity Check please!

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AChristie76

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Sep 11, 2014
59
Oviedo, FL
Hi,

I've been having a tough time balancing my pool. It's my first season with a pool, so I'm still in the learning curve, but I would like to bounce my concerns off you and see if that can give me a new idea or mindset...

My tf-100 numbers first:
FC (failed an OCLT last night): 4.5ppm at 8pm. 2.0ppm at 5am.
CC: 0.0 at 8pm. 0.0 at 5am.
pH: 7.5
TA: 90
CH: 350
CYA: 30

The water is clear, but since I failed the OCLT I told the wife to not let the kids swim today and pumped up the FC to 12ppm (per the FC/CYA chart)...following the process. More brushing and testing this evening.

Here's where I need a sanity check, am I doing things about right?
I'm been running the pump for 12 hours a day and I've got my SCWG at 85%. My FC keeps slowly lowering and I've been supplementing with bleach more frequently than I'd like. We've had a ton of sun and a ton of rain lately in Central Florida, so I realize I'm burning off chlorine (sun), and decreasing CYA (rain and drain off/splash out)...a double-edged sword.

Does my pump time and SWCG level seem about right for a pool in CFL? Seems like too much run-time to me, but I don't have any basis for comparison. I've been trying to up the CYA level, one sockful at a time, and when I test, I re-run it a couple of times to verify the value (the reagent is about 3 months old).

I don't have any ladders or rails in the pool. But do have a wide rock faced spillover from the spa to the main pool. I keep up on brushing the rock, but there are many 'nooks-and-crannies'. I'm hoping that when we designed and built the pool we didn't create a permanent and unchangeable home for algae. Anybody else have a rock spillway? Do you do anything in particular to keep it clean?

Or perhaps I just need to make my way through another SLAM....but then I'm afraid my FC will creep down again, and I'll be back in the same position.
What bugs me too, is that I've read posts here from folks that say they haven't SLAM'ed in years...is it just that these people have such a deep understanding of their chlorine that they can predict when and how much to add?

Very much appreciate your input! Thank you
 
Hi Adam! Welcome. Great to see you using the TF-100! Some thoughts here:
- Are you actively trying to SLAM and meet the 3 criteria? Your water seems clear, so did you see any algae trying to form?
- Remember, with a SWG your Recommended Levels for some things (i.e. CYA) are higher). Please see the links below to help you gauge (70-80)
- Note that CYA won't register on your tests until a few days after it was placed in the pool
More info to follow. I hope some of this helps you until others chime in. :)
 
Hey - thanks for quick reply!

I wasn't actively in a SLAM, until I kicked it up to 12ppm this morning, due to dropping 2.5ppm overnight. But I had a suspicion before then...my chlorine was just moving down too fast for my liking, and I had been adding bleach too often. With the SWCG up to 85% and 12 hours a day, I feel like it should make enough chlorine to sustain the need. Am I wrong? Do other SWCG owners need to supplement frequently?

I have not seen any algae form, but with all the rock, I have concerns it may be hiding (even with the almost-daily brushing).

I've been trying to boost CYA for a while...one sock, wait about a week, retest, add a sock, wait a week, retest. Wash, rinse, repeat =)
 
If you failed an OCLT then something is eating away your chlorine. In the day time you are fighting both the algae and the sun. This is why your SWG can not keep up. Kill the algae and the SWG should work much more efficiently.
 
You're doing correctly with the sock Adam. True, it's possible your FC is battling something flowing from your water feature I suppose. All you can do is process of elimination. Perhaps first - commit to a SLAM now while you're CYA is not too high, that way you will require less bleach. You're water isn't too bad, so the SLAM hopefully will be accomplished fairly quick. After the SLAM, watch your levels. If the cc climbs, or FC drops drastically, it may be time to re-evaluate everything/anything that your water comes in contact with. Also true that many SWG owners will rely primarily on bleach while doing the SLAM to save on the SWG/cell. As to how long to let it run each day, I would have to let other TFP'ers chime-in on that one. But as Scuba_Steve mentioned, once your water is balanced and not fighting the sun and any issues with the water, your SWG should be efficient.
 
9pm: 12.5ppm
5am: 10.5ppm

SLAM goes on.

I do have a question. What I've found is that normal grocery store/walmart bleach is 8.25% and it's Active Ingredient is "Sodium HydrochlorITE"
Walmart also carries in the pool section something not labeled bleach, but named Chlorizor (or something like that), where it is 10% "Sodium HydrochlorIDE".

What's the difference between the two? Are they bleach, and bleach-strong?

I'm waaay far past from 11th grade Chemistry class...but a quick google search tells me that regular bleach is polyatomic and carries an extra oxygen atom. The Chlorizor is monoatomic, lacks that extra oxygen. But, at the heart of it, I dont know what that means.
 
I don't know very much about chemistry. I do know that chlorine works by oxidizing things. I would imagine that having more oxygen atoms would make it more reactive. Then again, it might make it less reactive because the oxygens are bound to each other...
 

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The "hypochloride" is a typo from the manufacturer. They meant "sodium hypochlorite" and it's essentially chlorinating liquid which is the same as bleach, just stronger. So you can use the 10% stuff if it's less expensive per FC. For simplicity, divide the cost by the percent to get a "cost per percent" as a rough guide for pricing. Technically a different factor is to be used for chlorinating liquid sold by Trade % compared to bleach sold by weight % sodium hypochlorite, but for your purposes you can just use the simpler $/% ratio for comparison.

The eHow article is incorrect about sodium hypochlorite being less reactive than normal chlorine (whatever that means) and that it raises the pH. They are forgetting that 1) chlorine is identical once in the water and 2) the pH drops back down when the chlorine is used/consumed.

Your Hayward T-15 is supposed to output 1.45 pounds per 24 hours which in your 12,000 gallon pool should be 0.60 ppm FC per hour. 12 hours at 85% should be 6.1 ppm FC which is a lot. Your OCLT failure indicates you've probably got nascent algae growth in your pool consuming a lot of chlorine and you need to do a SLAM to get ahead of that. After you've dealt with the algae and you get to a normal OCLT and reasonable daily usage, then you can raise your CYA so that your cell doesn't have to work as long and that should help you keep your pH in line and also have the cell last longer. But first you've got to kill off the algae in the pool.
 
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