- May 3, 2014
- 59,072
- Pool Size
- 6000
- Surface
- Fiberglass
- Chlorine
- Salt Water Generator
- SWG Type
- Pentair Intellichlor IC-40
All bleach has some sodium hydroxide in it. Minuscule amounts. Part of the manufacturing process.
Pool Chlorine Level Keeps Dropping (Please help! Incurring astronomic costs in chemicals)
- Thread starter qsch1
- Start date
aehaas
Member
"Photometers are not accurate"
Buy cheap and you get poor results, buy professional equipment and get professional results. I am a biochemist and stand by my recommendations. 'No connection to the products I recommend. Price is no object for me. (Though, like some, I do not necessarily spend more than needed). I demand accurate results and these products do the job. You will be shocked how values/results vary among testing methods. All I can say is that I had trouble getting my 34,000 gallon pool in Florida perfected. No issues for years after I got better testing equipment and followed my basic rules. NO Trouble since.
FYI - I do pool care once a week. I generally over treat the acid addition by a little as it does not have to be treated as often.
ali
Buy cheap and you get poor results, buy professional equipment and get professional results. I am a biochemist and stand by my recommendations. 'No connection to the products I recommend. Price is no object for me. (Though, like some, I do not necessarily spend more than needed). I demand accurate results and these products do the job. You will be shocked how values/results vary among testing methods. All I can say is that I had trouble getting my 34,000 gallon pool in Florida perfected. No issues for years after I got better testing equipment and followed my basic rules. NO Trouble since.
FYI - I do pool care once a week. I generally over treat the acid addition by a little as it does not have to be treated as often.
ali
- Mar 5, 2020
- 3,190
- Pool Size
- 66000
- Surface
- Plaster
- Chlorine
- Salt Water Generator
- SWG Type
- Astral Viron V35
Thank you for sharing your real life experiences, much appreciated. Just one note on pH and chlorine efficiency.
What you are saying is correct for a pool without CYA, where the equilibrium between HOCl and OCl- is the only relevant equilibrium that affects HOCl, which is the effective sanitiser/oxidiser. In this case, the HOCl concentration decreases by 50% between pH 7.5 and pH 8.0 by turning into OCl-.
With CYA, chlorinated cyanurates add to the equation, and the HOCl concentration decreases now by only 15% between pH 7.5 and pH 8.0. As HOCl turns into OCl- with increasing pH, more chlorinated cyanurate turns into HOCl, compensating for most of the loss from turning into OCl-.
The remaining small pH-dependency is considered in TFP's recommended levels and can be ignored in everyday pool maintenance.
I am open to your recommendations. If enough people confirm what you've found, I'd recommend it to the people who are looking for such. The cost isn't even a rounding error on some of the pools being built here.
It would also potentially solve a problem for people that pay as much to ship Taylor internationally, or can't ship Taylor internationally.
How long have you been using it ? There were a couple other units that worked well until they didn't at a year or two.
- Mar 5, 2020
- 3,190
- Pool Size
- 66000
- Surface
- Plaster
- Chlorine
- Salt Water Generator
- SWG Type
- Astral Viron V35
This looks OK.
Sodium Hydroxide (also called lye or caustic soda) is expected to be there. Bleach is manufactured by electrolysis of a brine solution (basically an industrial sized SWG). The produced chlorine gas is bubbled into Sodium Hydroxide where the chlorine turns into Sodium Hypochlorite and chloride. You end up with a solution of Sodium Hypochlorite, salty water and some excess lye.
What we are concerned about with household bleach is that they often add fragments, "splash less" agents, etc. These, we don't want in a pool. But that doesn't seem to in this bleach. It's only 5% strength compared to 10% or 12.5% as "liquid chlorine" sold for pools. But that's OK, you just need a bit more, PoolMath will tell you how much.
Last edited:
aehaas
Member
I have used the test equipment for at least 10 years. The photometer is that old. The pH meter needs a new probe about every 3 years, about $60.
Ali
Ali
- Jun 1, 2018
- 14,015
- Pool Size
- 26000
- Surface
- Vinyl
- Chlorine
- Salt Water Generator
- SWG Type
- Hayward Aqua Rite (T-15)
Leslie’s / local pool store also has very expensive photometer equipment as well. I suppose the pool store employees aren’t typically chemists so it could be operator error on their part.
Their system has overwhelming evidence here against it. Then they confirmed what we knew about their tolerances, with most +/- 25% when in range.
Copper and iron have 100% variance at the threshold for possible staining.
aehaas
Member
The photometer I recommended has accuracy ranges from 2 - 10% with the least accurate test (10%max) is alkalinity. The chlorine is at 5% within a test range of 0-12.
ali
ali
So I have now started slam and at my last logs, I need a slam level of 28. I managed to get the CYA down to 70 by filling the plunge pool below my pool with fresh water (1000-2000 Gallons). I assume all I need to do now is keep that level of 28 and check it and boost up as much as I can and also sweep the whole pool. Then after check overnight chlorine pool loss and if it’s less than 1 I am good?
You need to satisfy all 3 SLAM criteria to count it as good -
No visible algae, alive or dead.
Overnight loss =<1
Combined Chlorine =<.5
And no need for the OCLT if the water isn't stupid clear or you're still seeing signs of algae. Any fail of the 3 continues SLAM.
Ok so after about 3 hours I checked it and the FC dropped to 19, as I need 28 for the slam, I put back in 3 gallons (5%) of the liquid chlorine I have to keep it at 28.
The more effort you put in, the faster it goes, no matter how bad it may be. When its reasonable, test/dose every 2 to 3 hours at first until the FC holds longer than that, then adjust your intervals accordingly. Usually if you hit it often the 1st day, the FC holds 6 to 8 hours the 2nd day. And maybe 12+ the 3rd day. It gets easier as it goes. Let the testing be your guide.
You can also test/dose early, say on a weekend, to buy you the next 3 hours running errands and such.
You can also test/dose early, say on a weekend, to buy you the next 3 hours running errands and such.
So basically this is what happened the first day. After about 3 hours I was asked to put in another 3 gallons. We brushed it a lot then after about 3-4 hours again I was asked to put in another 4 gallons. It’s the end of the day now, shall I do more tonight or wait until the morning? We scrubbed it well, and it looks quite clean. I think the filter must be pretty dirty now so asked the gardener to come tomorrow to change that. I am down to 4 gallons left from 20. I was told that 10 gallons of 15% should be enough. They are only 5%, not 15. I assume I need at least 8 more gallons what are your recommendations?
- Mar 5, 2020
- 3,190
- Pool Size
- 66000
- Surface
- Plaster
- Chlorine
- Salt Water Generator
- SWG Type
- Astral Viron V35
10 gallons are a good start. That's enough to get up to SLAM and see how quickly you go through it. And then buy more. Every SLAM is different, you have to go with the flow. The more often you check and get back to SLAM level, the faster the overall process, but there's also no point in getting paranoid. I would check one more time once it's dark.
In your case with limited reagent access and relatively high SLAM level, I would even consider using a 2.5ml sample (measured with a syringe) and have 2ppm per drop resolution for the test and dose. Just assume for the dosing that FC is 2ppm lower than you tested to calculate the next chlorine top-up. You might overdose slightly, but wasting a bit of chlorine is in your situation better than running out of reagents mid-SLAM, I'd say. Or make a 50:50 mixture of pool and rain or distilled water and take a 5ml sample of that to get 2ppm per drop.
In your case with limited reagent access and relatively high SLAM level, I would even consider using a 2.5ml sample (measured with a syringe) and have 2ppm per drop resolution for the test and dose. Just assume for the dosing that FC is 2ppm lower than you tested to calculate the next chlorine top-up. You might overdose slightly, but wasting a bit of chlorine is in your situation better than running out of reagents mid-SLAM, I'd say. Or make a 50:50 mixture of pool and rain or distilled water and take a 5ml sample of that to get 2ppm per drop.
It’s not possible to predict how much chlorine is needed. You’re gonna need more most likely. You keep going as long as it takes to meet the 3 criteria to stop.
Can I use 5 ML pool sample water and then add the drops to test the chlorine. Each drop should be 1.0. Or how would that one work? You are saying to use 2.5 pool sample water 2.5 rain water and each drip will be 2 ppm?
I also checked my Calcium Hardness just and it is now reading as 850 from 750 a few days ago and the Total Alkalinity is 70 from 120 (it dropped). I have also checked salt and it is now 4400 from 5400 due to adding more water to the pool. I assume the high chlorine levels could be causing some discrepancies.
Last edited: