Mixed Chemicals = Cloudy Swim Spa / Pool

[milhouse19]

NOTE TO ALL: This poster's pool is INDOORS and is functionally a SPA, not a POOL (95 degrees year round). The standard advice we give here does NOT apply!

I have a 3000 gallon (indoor) Endless Pool which has been stable for about 2 years using Chlorine. I recently had a part replaced that required draining about 1/3 of the pool (this past Saturday). After filling it back up, the balance was off and the installer added PH raise and Alkalinity raise at the same time. Then as he was leaving he added a clarifier. 6 hours later when I take off the cover it was completely cloudy with maybe 18" visibility and a slightly green tint. I don't think the cloudiness was caused by anything mechanical (Endless Pools just use a cartridge filter which wasn't changed and 2 Nature2s which were replaced), but I can't be certain.

After talking to a (different) pool professional, he told me to shock the pool which I did on Sunday.

As of this morning (Wed.), its still cloudy. All pool levels are ok (PH is a bit low, but not terrible) except for Chlorine which is so high its off scale., The cloudiness may have slightly improved, and it looks more blue than green, now, but really its not much better. I ran the filter for about 12 hours yesterday.

If it matters, since its indoors, it doesn't get a lot of sun so I haven't been able to burn off the Chlorine. Also, the pool is kept around 95 degrees since its for my wife's therapy.

Any suggestions on how to clear the pool? I don't mind waiting a few days, but its been 4 now and there has been little improvement. If I have to empty and refill, I'd rather do it sooner than later. I'm also worried that the chemicals will damage the liner - I've already had issues with Endless Pool liners.


Unrelated, I am thinking of switching from Chlorine to Bromine if I have to empty and refill, but would like any input on whether that's a good idea. The itchy skin and destroyed bathing suits are taking a toll, plus I understand Chlorine works best around 75 degrees, while Bromine works better at higher temperatures.


Thanks

[PoolDoc]

NOTE TO ALL: This poster's pool is INDOORS and is functionally a SPA, not a POOL (95 degrees year round). The standard advice we give here does NOT apply!

Hi Millhouse;

Not so short answer on how to clear it:

# drain it, and refill.
After 2 years of use, a spa is long overdue for a drain and refill. Un-filterable, un-oxidized residue builds up in spas because they are not UV-irradiated and are much smaller relative to the bather load, than pools. However, before draining, add 4 full gallons of plain 6% household bleach and allow it to circulate uncovered for 6 hours or so BEFORE you drain. You will probably need to make sure windows and such are open before you do this. If you can't do so, add the bleach AFTER you refill, and then dechlorinate with hydrogen peroxide (BaquaShok)

# ditch the Nature2 cartridges.
The only possible positive effect of Nature2 is anti-algae, and to prevent growth of bacteria like Legionella (http://en.wikipedia.org/wiki/Legionella). But algae is not a problem on indoor pools, and if you chlorinate effectively that will never be a problem. Worse, it's unlikely the Nature2 units are working for that purpose. If you want to use copper on your unit, using plain copper sulfate would be a better choice. Under certain conditions, like when adding acid, the Nature2 units may unexpectedly release copper into the water.

# forget about bromine.
I'm going to ask Chem_Geek to look at this, but I'm not aware that there is any substantial support for the marketing claim that bromine works better at higher temperatures.

# replace your filter cartridge
Essentially for the same reason you should replace your water.

# limit future water treatment to 5 chemicals, and no others:
1) plain 6% household bleach (to chlorinate)
2) muriatic acid (to lower pH)
Dilute 1 part acid to 3 parts water BEFORE storing. (Be VERY careful. Do this OUTDOORS, while wearing gloves and glasses. Have a running water hose beside you to rinse way any splatters. Do NOT breathe the fumes.) Once diluted, the acid will no longer fume, but still should not be stored indoors.
3) borax (to raise the pH)
4) hydrogen peroxide (to dechlorinate)
5) polyquat algaecide (used at 2x the listed dose to 'keep' the pool any time you plan to neglect it)

# reduce skin and eye irritation with borax, and possibly with salt.
50 - 100 ppm borax will inhibit growth and reduce eye / skin irritation somewhat. Up to 5,000 ppm salt will reduce both significantly . . . but check with the manufacturer -- adding salt may void your warranty.

# do NOT use any of the 'special' spa or pool chemicals.
Many of these are a hobo-soup of chemicals with unpredictable results, or create known long term complications.

# plan to drain the spa 100% at least every 6 months
(I'm assuming it is used regularly)

# monthly, shock to 20 ppm (about 1 gallon of bleach) and then dechlorinate
after 8 hours or more. Leave the spa uncovered during this period and ventilate the area

# if you want to reduce odors and negative effects further, you can try 20 - 30 ppm stabilizer,
which will enable you to maintain higher chlorine levels without damaging swimwear or affecting eyes.

# get a Taylor K2006
so you can accurately test your water yourself. Use it to work out a routine so that chlorine levels can be maintained consistently. Levels should never, ever be below 1 ppm.

# if your spa is private, ask your wife to skip the suit.
Not only will this eliminate the suit deterioration issue, it will eliminate the skin and sanitation issues that come from half-dried suits used on indoor pools.

Obviously, there are specifics here I haven't included. But if you want to follow this plan, let us know and I'll work out the details.

[milhouse19]

When I initially had the pool installed we tried to use plain bleach to chlorinate, but it seemed like no matter how much we added (in some cases multiple gallons), it was never enough and the pool eventually had some sort of algae or bacteria floating in it. Switching to Chlor-Brite took care of it and as kept it clean, until now.

Also, draining and refilling every six months isn't an option, unfortunately, as heating 3000 gallons to 95 degrees using the stupid electric heater can take 5-7 days of 24/7 use, resulting in electric bills over $1k for that month.

Thanks for the in-depth reply. I'll have to think about some stuff.

[True Blue]

Let me add, that in diluting your muratic acid that you NEEd to add acid to water, never the other way around.

[PoolDoc]

That's a good rule of thumb, but it doesn't really matter with muriatic acid. Unlike the case with sulfuric acid (the only other liquid acid commonly available to poolowners), the reaction of muriatic acid with water is not exothermic.

[True Blue]

The dissolution of hydrochloric acid (muriatic acid) is not as exothermic as sulfuric acid, but it is indeed exothermic.

[PoolDoc]

When I initially had the pool installed we tried to use plain bleach to chlorinate, but it seemed like no matter how much we added (in some cases multiple gallons), it was never enough and the pool eventually had some sort of algae or bacteria floating in it.

. . . . .

Also, draining and refilling every six months isn't an option, unfortunately, as heating 3000 gallons to 95 degrees using the stupid electric heater can take 5-7 days of 24/7 use, resulting in electric bills over $1k for that month.

Chlor-Brite is dichlor . . . if you've been using that for 2 years, wow! Your stabilizer level must be really high. You NEED that Taylor testkit.

But chlorine is chlorine -- if you aren't losing to sunlight, then when you lost the bleach, you would have lost an equivalent amount of Chlor-Brite. There may have been 'goo' in your unit that you cleaned up with bleach before you switched to dichlor. Or, you may have been buying "pool bleach" which can often (especially in summer) have less, possibly much less, chlorine than the label says.

Regarding refilling, if you can't do it 2x a year, at least do it annually. You can refill now, and the incoming water (at least here in Georgia is around) 75 degrees.

But lemme do some calcs:

3000 gal * 8.3 #/gal = ~25,000 lbs of water.
delta T = 95 - 70 = 20 degrees (now)
delta T = 95 - 35 = 60 degrees (winter)
BTUH req'd = 25,000 * 20 or 500,000 BTUH (now)
BTUH req'd = 25,000 * 60 or 1,500,000 BTUH (winter)
3412 BTUH = 1 KWH
So you need . . .
500,000 / 3412 KWH in summer = 146 KWH
1,500,000 / 3412 KWH in summer = 439 KWH

The highest residential rates I know of are less than $0.20/KWH, so summer water heating costs should be $29 and winter should be $87.

Let's keep going. A standard inconel sheathed 4500W water heater element requires a 30A 220V circuit, costs about $30 and can be set in 2" copper pipe, if you maintain continuous flow. It transfers heat at over 98% efficiency and is compatible with pool water. It should heat your pool in summer in 33 hours, and in winter and about 100 hours in winter.
[ 5500W: http://www.amazon.com/Camco-02933-Sc.../dp/B001RD7MK0 ]

So . . . if it's costing you anything approaching $1,000 to heat a fresh filled spa, something is seriously wrong, either with your installation, or my calculations.

[chem geek]

The standard Water Replacement Interval (WRI) in days for a spa is (1/3) x (Spa Volume in U.S. Gallons) / (# of Bathers) where the soak-time is usually 20 minutes or so, but that's for a hot (104ºF) spa. For a pool, you could go 3-6 times longer depending on temperature so let's say 3 times for your pool. If one person uses the pool every day for one hour (so that's the factor of 3 we're assuming for equivalent hot spa use), then we have (1/3) x (3000 gallons) / (1 person) = 1000 days or 2.7 years. If you are using this pool with more people or for longer than an hour per day, then the water would need replacement sooner. 95ºF is pretty warm so perhaps you only get 2x the WRI so less than 2 years. The point is that you are around the edge of what you can get away with for water replacement. Replacing every 6 months should not be necessary -- that's the timeframe for a real 350 gallon spa for 30 minutes of one person soaking every day and using the Dichlor-then-bleach method (Dichlor-only needs a water change in half that time so twice as frequently).

As for chlorine vs. bromine, there is nothing wrong with using chlorine at higher temperatures and many spa users with hot (104ºF) spas use it successfully, BUT the key is to use some Cyanuric Acid (CYA) in the water otherwise the chlorine is too strong. It sounds like you have been using chlorinating liquid or bleach without having any CYA in the water (either from adding pure CYA initially or by using any stabilized chlorine, Trichlor or Dichlor, products). The itchy skin and destroyed bathing suits are most likely from your high Free Chlorine (FC) levels with no CYA.

As for your chemical regimen, the only addition I'd make to what Ben listed would be to add some CYA to the water (he does mention this later in his suggestions). Probably using 20 ppm CYA is sufficient and you would then target 2-4 ppm FC as your normal FC range. This is somewhat higher than normal FC/CYA ratio in order to help oxidize bather waste faster and reduce the amount of measured CC, but you may need to use supplemental oxidation as well if you find that CC persists. For hot spas, the high temperatures break down the bather waste with chlorine fast enough, but I'm not as sure how 95ºF will do -- I think it will be OK. I know that 80ºF in an indoor pool doesn't do well without supplemental oxidation or UV in sunlight.

I wouldn't add 5000 ppm salt. There's too much risk for corrosion unless you are very familiar with your equipment and know that it will tolerate such levels. 50 ppm Borates is something many people find helpful for a shimmer to the water, but I'm not so sure it will have as noticeable effect on skin. The irritated skin came from the FC with no CYA and you'll be fixing that by orders of magnitude.

[milhouse19]

Thanks for all the info.

I'm curious why no one seems to favor Bromine. My installer encouraged me to switch to it (with no financial incentive for him). Is it just price or is it more work than Chlorine?

[PoolDoc]

I'm sure he believes it's true that you should. It's been a 'truism' in the pool/spa business for year, although without much foundation, that chlorine was for pools and bromine was for spas. It's one of those things I wrote about years ago, things that 'everyone' in the pool biz knows to be true, but aren't.

*If* you actually use only bromine . . . which means using sodium bromide and bleach, there might be some benefits. But there's quite a bit of data from Canadian and British studies that hydantoin from bromine tabs builds up and causes real problems.

By the way, I don't think Chem_Geek noticed that you were using Chlor-Brite, which I assume is the Leslie's dichlor, so instead of not having enough stabilizer, you probably had too much.