cloudy water after super saturation with chlorine, normal?

Causes and cures for cloudy swimming pool water.
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tjvisions

cloudy water after super saturation with chlorine, normal?

Postby tjvisions » Fri 13 Jul, 2007 08:37

We are new owners of a home with an in ground 30,000 gal pool. we have had issues with the water chemistry since we purchased the home last month. The pool would just not hold chlorine. After doing an overnight demand test at the local pool supply store, the pool company told me that I was not holding chlorine and that I needed to add 55lbs of chlorine to hit that threshhold to allow the pool to hold chlorine. She gave me a list of ingredients to buy and directions on what to add...here is what we did.

We started on Wed PM and added 12lbs of sod bicarb (balance pak 100) and waited an hour before adding 18lbs of sod carb (balance pak 200). After 15 minutes, we added 55lbs of fast dissolving chlorine (super soluble). The filter (DE) was running after starting this process and he water was hazy when starting.

On thursday morning, the water was much more blue in color, but very hazy. I was barely able to see the bottom in the deep end at 8.5 feet. I backwashed the filter and continued to let it run which seems to clear the water to some extent.

This morning, I expected the pool to be much better however, it looks worse. It is very cloudy, unable to see the drain at the deep end. My filter pressure is the same as after the backwashing the day before. My free chlorine is high, my ph is low (below 6.8 ), total alkalinity is way over 200.

I just am unsure whether I have been given wrong information on what to do or whether this is normal and will clear in a day or two. Any advice from the experts is greatly appreciated!


chem geek
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Postby chem geek » Fri 13 Jul, 2007 10:01

Unfortunately, you were given wrong information. Your pool is probably cloudy due to having too much Total Alkalinity (TA) though usually a low pH would prevent such cloudiness -- but this depends on your Calcium Hardness (CH) level. Also, if the fast dissolving chlorine was Dichlor powder, then you probably significantly increased your CYA level.

For your 30,000 gallon pool, adding 12 pounds of sodium bicarbonate and 18 pounds of sodium carbonate would cause the pH to go towards 9.0 and would add 96.4 ppm to your TA level. The 55 pounds of Dichlor dihydrate (if that's what it was) would increase your Free Chlorine (FC) level 121.7 ppm and your Cyanuric Acid (CYA) level by 110.8 ppm! The pH would initially drop to around 8.6 and your TA level would increase (from the CYA). As the chlorine got used up, the pH would drop to around 6.8 and the alkalinity would drop to be around 54 ppm higher than you started.

If this sounds insane, well it is. If the Free Chlorine (FC) level is still very high, then the pH test is worthless since high chlorine levels well above 10 ppm will interfere with the test. First of all, get yourself a good test kit, the Taylor K-2006 you can get from Taylor here or from Leslie's here or the even better test kit based on the K-2006 from tftestkits here . With accurate numbers, we can then figure out what to do next. If you really added 55 pounds of Dichlor and have your CYA at 110, then we KNOW you'll have to do a partial drain/refill of your pool to lower the CYA (i.e. to dilute it), so perhaps you can get started on that now while waiting for your test kit. The dilution will also lower your TA so this should reduce cloudiness as well. If your pH is really on the low side, then you'll want to raise it, but you can just to this with some aeration since your TA is high.

I certainly hope the extremely high chlorine level didn't cause any damage. The only saving grace is that the pH was high when you added it so the chlorine wouldn't be as powerful.

Richard
tjvisions

Postby tjvisions » Fri 13 Jul, 2007 19:59

Richard, Thanks for your detailed response. I have ordered the kit you mentioned, however it wont arrive for a week. In the meantime, I have tested the water again today with my kit and the chlorine seems to be in the 3.0 range and the ph is still low. It is much yellower than the 6.8 color low range that I have on my kit. The cloudiness is now gone and the water is clear and blue. I have added some balance pak 200 to try and raise the ph. After adding it, there was some residue on the surface which has never happened before. I will take in another water sample to the local pool supply store to test so i can get more detail numbers....I will post the numbers when I get them. Thanks again
tjvisions

Postby tjvisions » Sat 14 Jul, 2007 09:17

After analysis at the pool supply store, here is what they have told me
TDS 1800, CYA 100, tot cl 4, free cl 4, ph 7.2, tot alk 190, hardness 370, quat 4. When i took the sample the water was crystal clear, i turned on the pool cleaner and left. An hour later, the pool is cloudy. Is this from the sun or water circulation from the cleaner? Does this still qualify for a partial refill?
chem geek
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Joined: Thu 21 Jun, 2007 21:27
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Postby chem geek » Sat 14 Jul, 2007 12:32

Yes, you need a partial drain/refill because your CYA is high (100) and you also have high TA (190) and CH (370) which when combined when the pH goes up will lead to cloudiness. Also, at a CYA of 100 you would need an absolute minimum FC level of 7.5 ppm to keep away algae (4 ppm FC is definitely not enough) and should target 11.5 ppm. I suspect the cloudiness is an algae bloom developing combined with some calcium carbonate over-saturation.

Also, the pool store's "100" for the CYA could be "100+" since some CYA tests only measure up to 100.

You should have your tap water (fill water) tested as well. It won't have CYA in it (or normally shouldn't) but it will have TA and CH so you can see what you will be dealing with initially.

Now what I've outlined is ONE option for you. You could try and live with your CYA level and just use an algaecide to keep away the algae such as PolyQuat 60 on an initial dose and then weekly maintenance. However, I think you'll be happier with a lower CYA level. It's much easier to shock a pool with far lower amounts of chlorine needed at the lower CYA level if you ever need to do that in the future.

Richard
tjvisions

Postby tjvisions » Sat 14 Jul, 2007 22:52

I will check the tap water with them as well. How much water loss is a partial drain and are there any products to help prevent this from occurring again? I know there are some ionizers and purifiers advertised, do they work and are they worth the extra money?
chem geek
Pool Industry Leader
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Joined: Thu 21 Jun, 2007 21:27
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Postby chem geek » Sat 14 Jul, 2007 22:58

If you replaced half of the water and your initial CYA was 100 then it would get reduced to 50. Partial, in your case, is pretty drastic.

As for preventing algae in the future, all you have to do is maintain the Free Chlorine level to be 11.5% of the CYA level with an absolute minimum of 7.5% of the CYA level. But if you think you cannot do that, then adding a weekly maintenance dose of PolyQuat 60 algaecide will keep the algae away. Other options, such as copper, have potential side effects (green water if pH goes up and green hair for blonds).

Even the manufacturers of Trichlor and Dichlor recommend you use a weekly algaecide. Of course, they make those as well, but it's actually one of the accurate pieces of advice they give. They don't talk about keeping algae away using chlorine alone and certainly not in any relation to CYA levels, but then you'd be buying bleach or chlorinating liquid instead of their product and where's the money in that?

Richard

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