Crazy Pool Readings! URGENT HELP REQUIRED ! PLEASE HELP!!!

[Anonymous [GDPR] European in the UK]

Hi,

Please could someone help.

I live in london, uk and have had crystal clear waters in my pool (approx 79000l) all summer. However after a recent pool party and my adding of chlorine and ph adjusters, the chemical readings are very strange. I was having difficulty understanding the readings using normal dye tests so went out and bought a SCUBA II digital reader to provide more accurate readings.

The readings I currently have are
PH7.4
Free Chlorine - My meter just says HIGH i.e. above measurable range
Total Chlorine - My meter just says HIGH i.e. above measurable range
Cyuranic Acid = 114
Total Alkalinity = 268

The pool has a turquoise / green tinge to it, there is some residue on the sides of the pool. Having said that it was just about useable today... even though it was no where near its crystal clear blue normal self.

The pool has a vinyl liner and an air source heat pump, with water heated to 30 degrees celcius.

Do I need to wait for chlorine levels to drop over a period of time?
Should I partially drain the pool?
Should I isolate / turn off the heat pump to avoid any damage due to high alkalinity?

I normally used stabilised chlorine granules to santise along with chlorine tablets in the skimmer.

Really hope somebody can help with meaningful advice. I would prefer not to drain the pool as it is so large to refill, but will do so if there is no alternative.

Hope you can help!!

S

[CarlD]

Hi Stan!
Sometimes, it's hard for us to help those outside North America, because some of the test kits and chemicals are very different. Can you get a simple OTO/Phenol Red test kit? Color matching tests CAN be tough to interpret but drop-testing is usually more accurate and easier. For example, the FC test goes from red or pink to crystal clear. The Total Alkalinity test goes from green to red. Ben, our site's owner, is very leery of ORP testers. I know little about them but they have to be calibrated frequently.

Your pH is OK, FC and TC don't tell us anything because we don't know what the limit of the normal range is. You can double whatever that range is, probably, by mixing pool water and distilled water half and half and testing the dilute mixture. CYA is very high. I'll bet anything you're using Di-chlor powder and Tri-chlor tablets. Stop. They have elevated your Cyanuric Acid (CYA) to a difficult range. And your Total Alkalinity number seems extremely high to me. Have you been adding a lot of baking soda to it? Do you have a Hardness measure as well? It's usually not relevant to vinyl pools unless extremely high.

At a guess, you have an algae bloom. The solution is not complex. You'll have to raise your chlorine level to a sufficient degree and keep it raised till the algae is dead. If your CYA reading is accurate, that means to an FC level of no less than 25ppm. It will take several days or more. You can use two chlorine sources. The first is our first choice, always: Bleach. Ordinary, unscented, house-hold bleach, the stronger the better. Liquid Chlorine, sold in pool stores here across the pond, is the same thing, only stronger. Here, "ultra" bleach is available in an 8.25% concentration. LC can be 12.5-14%. It's all called "Sodium hypochlorite". Alternatively, if your hardness level is low, the lower the better, you can use Cal-Hypo powder--calcium hypochlorite. Cal-Hypo doesn't add CYA but does add calcium. Again, if you're not getting close to 400ppm (hardness) it's not a problem.

How much? While we figure in US gallons here, the ratios are the same. Here's the rule of thumb for bleach: If the concentration is 8.25%, one liter of bleach will add 8.25ppm of chlorine to 10,000 liters of water. But it will take two liters of 8.25% bleach to add 8.25ppm of FC to 20,000 liters. So you'd need ROUGHLY 8 liters of 8.25% bleach to raise your pool by 8.25ppm. That works for any concentration--5.25% adds 5.25ppm, 14% adds 14ppm.

Not sure I can do the conversion on Cal-hypo so well, but I estimate that 325 grams of 65% Cal-Hypo powder will add 10ppm of chlorine to 79,500 liters of water + 7-8ppm of calcium.

Meanwhile, read our various forums on dealing with algae, and go to our sister site, PoolSolutions.com and read everything you can.

That's just for starters.

Good luck!

[Anonymous [GDPR] European in the UK]

Thanks Carl.

Appreciate the advice. The pool meter that I have is meant to be quite accurate...
http://www.lovibondwater.com/product/scuba-ii.aspx

The Chlorine level reaches up to 6mg /l so we know that chlorine level is higher than this. I will try your method of diluting the water to get an proper chlorine reading.
I have read that my Cyunaric acid levels should be no more than 100 ppm, so although mine are high... they may not be exceptionally high.
Yes I have been adding some kind of baking soda to help stabilise ph.

A local pool person has suggested the following

- Keep the pool cover off to help the sunlight breakdown the high chlorine
- Brush the Algae so that it combines with the free chlorine in the water
- Add some fresh water where possible to help dilute
- Drain a little of the old water where possible to help dilute

He suggested doing the above before adding any more chemicals. Do you think this is a sensible approach?

Many thanks!

[CarlD]

Hi Stan!

Stop adding baking soda. It's not doing you any good and it's raised your Total Alkalinity into a very,very high level.
I don't know how 6 mg/l translates to ppm though this converter I found seems to indicate they are almost the same thing. So your FC measure tops at 6...and you need to get it 25!
Try diluting 3 parts of steam distilled water to 1 part of pool water and see where the meter reads it--then quadruple the reading. If it doesn't hit the "HIGH" mark you need more chlorine.

Here's what I think of your pool guy's advice: Most of it's not going to do any good.

CYA of 100ppm means you need to MAINTAIN a free chlorine level of between 8 and 15ppm, and you need to shock at 25ppm. Lowering your FC before your algae is dead is not going to work.

Pool guy's advice:
While sunlight will break down chlorine, when CYA is over 100ppm, it won't do much, especially since you are at such a high latitude that the sun is much weaker. CYA is like sunscreen for chlorine, and you've got an excess of "sunscreen". It's also NOT what you want to do re: algae.
Brush the walls and floor of you pool to knock the algae loose. Yeah, that's good advice. Do it every day, but if you aren't going to raise your chlorine it won't help.
Fresh water won't hurt, but the only things YOU should want to dilute are you high CYA and TA levels. To cut your CYA in half you need to replace half your water.

The first won't help (probabaly won't hurt), the 2nd is good, and the last two are like trying to dig a coal mine with a teaspoon. Gonna need a LOT bigger shovel!

http://www.unitconversion.org/concen...onversion.html

[Anonymous [GDPR] European in the UK]

Carl

Really appreciate your help. Sorry to ask further questions... but you seem to have greater knowledge than me.

1) My current chlorine level is above 6 (my meter only reads up to 6), but we can conclude it is very high! If I add more chlorine as you suggest, will that not make my chlorine exceptionally high.... it will take over a month for the chlorine to return to normal levels no?
2) Adding more chlorine will not reduce my CYA level, or improve my alkalinity level. So I will still have CYA of well over a 100 no?
3) Can I not try adding some Algaecide instead as an alternative to shock chlorine? This would prevent the need for me to reach epic levels of chlorine no? Just worried as my meters normal range stops at 6 and yet you are suggesting shocking to 25 ppm. Seems really high to me... I wouldnt be able to use it for ages right?

Sorry to ask further questions

S

[CarlD]

Stan,

Check our sister site for lots of great information on the relationship of chlorine to stabilizer and how to test:

http://poolsolutions.com
http://poolsolutions.com/gd/best-gue...ine-chart.html

1) You need to know WHERE your chlorine actually is. Try using the dilution method to get an estimate. If your tool reads "HIGH" when you've diluted 1:1, then your FC is over 12. If it reads "HIGH" when you've diluted 1:2 (1 pool to 2 distilled) then your FC is over 18. Etc.

You are worrying about chlorine levels being too high when your PROBLEM is algae keeping your pool green and keeping your water for being sanitary. It's like the old joke:
"When you are up to your (waist) in alligators, it's hard to remember that the objective was to drain the swamp". You've got alligators (algae) and you're worried about the swamp.

2) Chlorine does not affect CYA or alkalinity levels. If you want lower CYA you must remove and replace water. So if your CYA is 100, you need to drain off and replace half your water to drop it to 50. Total alkalinity is lowered by lowering pH, then aerating the water to raise pH without raising TA--that's a discussion for when you're rid of the "alligators"!

3) There is only one algaecide we recommend and that's mainly as a preventative, not a cure. That's Polyquat 60%. Everything else has ammonia and/or copper and or bromine and cause far more trouble than they are worth. Look at the table I referenced--the "Best Guess" table. 25ppm is ONLY high if your CYA is low. CYA is a two-edged sword that protects your chlorine from breaking down in UV rays but also slows down its effectiveness. Handled properly, it can be a boon, handled incorrectly a bane. High CYA and correspondingly high FC levels can keep a pool from losing chlorine in hot, sunny climates. Some pool service companies use CYA=100 so they only have to show up once a week because the chlorine holds. Some of our members in hot states keep CYA = 80 and maintain their FC between 5 and 10ppm.

If your CYA was between 10 and 20ppm, you'd be shocking at 12ppm of FC, not 25ppm.

Once you get your algae clear, you'll need to keep your FC between 8 and 15, just for maintenance! Yup. That's really true. And yes, you can safely swim in it when the FC is that high--because the CYA is that high. You can even swim in it when it's 25--as long as the algae is dead and it's clean. It won't hurt your skin but if it's 25 wear older bathing suits because they made fade.