CYA.......and others

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I seldom, if ever, respond to LONG posts with random multiple questions. To answer them correctly takes wa-a-a-y too much time for those of us who respond frequently.

Sometimes, I do not know the answers to so many questions so I favor those posts that are presented succinctly and I can answer succinctly.
 
Re: CYA....

My apologies. Just typed what was popping in my head. Point taken. I'll just be straight to the point.

If the effect of CYA was being incorrectly posted by Pool Math then why is not being corrected? It freaked me out when I saw that it could affect the ph by upwards of 3. I also read that the granules take time and will drift the ph on the low side. Myb I've read too much.

Looking for a solution, I searched for "CYA & low ph" and saw the suggestions of using borax. Something with dropping ph while keeping TA, so I went for it. Now what's done is done. Could anyone suggest what I need to do now—MA?
 
Re: CYA....

peachy said:
My apologies. Just typed what was popping in my head. Point taken. I'll just be straight to the point.
Click to expand...

No worries, I do "stream of consciousness" posts sometimes too....but I've learned to delete them before hitting the "Submit" button ;)


peachy said:
If the effect of CYA was being incorrectly posted by Pool Math then why is not being corrected? It freaked me out when I saw that it could affect the ph by upwards of 3. I also read that the granules take time and will drift the ph on the low side. Myb I've read too much.
Click to expand...

From the section of PoolMath entitled "Effects of adding chemical"

Note: pH calculations are not exact. These numbers are only suggestive of the relative magnitude of the pH change you can expect. Small changes, +-0.4, with pH between 7.2-7.8, TA around 80-120, and Borate near zero will be approximately correct. The further you go from those ranges the less these pH changes will correspond to reality.
Click to expand...

In that section of Pool Math, certain assumptions are made about your water chemistry to do the calculations. In reality, pH calculations, even for simple chemical systems, should always be performed by iterative mathematical calculations to take into account the effects of changing alkalinity, buffering, etc. Since PoolMath just uses Java as it's calculation engine, those types of complex mathematical programming are not available and so assumptions have to be made. Like the note says, if your adding small amounts of chemicals, then the calculations are approximately correct. For large changes, it's only suggestive of the direction not really the magnitude of change.

peachy said:
Looking for a solution, I searched for "CYA & low ph" and saw the suggestions of using borax. Something with dropping ph while keeping TA, so I went for it. Now what's done is done. Could anyone suggest what I need to do now—MA?
Click to expand...

No, don't do anything now. If your pH is up, just use MA to bring it down. There's no getting rid of borates once they are in the water but they will decrease over time with backwashing and water exchange.

Good luck,
Matt
 
Re: CYA....

Thanks. It's really nice around sunset and the lights are on. :D

TA: 80
CYA: 40–50 (ran it twice)
FC: 4
PH: 7.6 / 7.8 (Blue Devil / Poolmaster)

FYI, both FC testers I have are OTO type.

Is there a way to estimate how much Cl needs to be added each day?
 
Without CYA in the pool, the pool guy used to just looked at the simple 2-way test kit and the ideal Cl level would be around 2-3 ppm. Some even labels 1 ppm as ideal. With CYA, the minimum is now 3-4 targeting 5-6. If the higher ppm will also result in higher lost, what's the advantage of having CYA?

If I want to run the pool w/ as low ppm Cl as possible, can I just keep it at minimum all the time? my father doesn't like Cl that's why he asked for an ozonator.
 
CYA protects chlorine from the sun and also buffers the harshness by a large percentage. CYA will help you use less chlorine not more. Without CYA the sun would burn off the chlorine in a couple of hours or less.

I have a saltwater pool in TX and keep my CYA around 80 and my FC around 10. The water is great and everyone loves it. There is little to no chlorine noticeable chlorine effects. People are amazed that they can open their eyes with no discomfort whatsoever.

More here, Pool School - ABCs of Pool Water Chemistry
And here, Chlorine CYA Chart

Also, see this on how to add CYA, Pool School - Recommended Pool Chemicals
 

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Running at the minimum FC is playing 'Algae Russian Roulette'. You leave yourself no margin for error and as soon as the FC drops below minimum the algae is then able to get a foothold. Once that happens the only way to get around it is to SLAM the pool which is painful doing it once -let alone twice or several times!

The FC/CYA relationship is a ratio and therefore the minimum FC required (approximately 7.5%) is a percentage of the relevant CYA level. Most chlorine loss is through sunlight so having a higher CYA level means that you are losing less FC and therefore not needing to add as much chlorine. It also helps to stabilise chlorine losses over a day so that it reduces the likelihood of going below the minimum FC.
 
Others have given you great answers so far but I would urge you to read the following thread by Chem Geek regarding advanced pool water chemistry as it will help you to understand why it is we teach a FC/CYA ratio - Pool Water Chemistry

The only way you can run a minimum level chlorine pool is to add a supplemental disinfection system in it which will cost you money. You could add borates to your water to 50ppm as describe HERE. Another option would be to use a supplemental algaecide, the best choice of which would be Polyquat-60. Finally, you could also regularly use phosphate removal chemicals to lower the nutrient levels in your water making it less hospitable to algae growth. All of these additional methods would probably allow you to operate your pool at the lower end of the FC/CYA range or even slightly lower than the minimums.

But, as you can clearly see, all of those "extra" methods require you to spend more money, time and effort to maintain proper chemical levels than just simply using chlorine. While I don't typically like to argue with other members about their perceived "sensitivities" to chlorine, I would submit that most people who say they "don't like chlorine" is because they have never swam in a pool with a properly maintained chlorine residual. Most bad reactions to "chlorine" are really due to pools that were never properly maintained and had high levels of combined chloramines (CCs). Also, public pools are typically operated with low or no CYA and so the FC levels used create a lot of hypochlorous acid which is harsh on the skin, hair and bathing suits. CYA, properly used, creates a much better swimming experience than most realize.
 
Holy cow! Tried to read a page off that "Pool Water Chemistry" thread and i think i will need to call my Chemistry 101 professor for that to be comprehensible. I'll skip that stuff. Do you guys all have some chemistry background or something?

I've added the higher Cl level of 5 ppm.

Should I bother trying to raise the ph or is that good enough? Dry acid or MA (cleaner variety)...
 
PH should be maintained between 7.2 and 7.8. Muriatic acid is the chemical of choice to lower PH, cheap and easy to get. If yours is still 7.6 then that is great.

I learned everything about pool chemistry right here on TFP. It is not as complicated as it seems at first. Once you dive in and start maintaining your water chemistry it starts to make a lot more sense.
 
do I now have 5 ppm CL and 7.8 PH based on this photo? tough finding the right colour especially when you have 2 OTO testers from different manufacturers that doesn't seem to match. I have not found FAS-DPD Cl tester locally.

is it right, at full sun exposure, even with 50 ppm CYA, the half life of Cl is around 6 hrs?

Cl.jpg
 

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