Mixed Chemicals = Cloudy Swim Spa / Pool

[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.

[milhouse19]

Sounds like Chlorine is the way to go.

So how does adding bleach before I drain the pool help? Wouldn't it just add more Chlorine to the overly-chlorinated pool?

In any event, I am going to drain and refill tomorrow. As a general rule, how much Chlorine would I need to add initially and add each week? Or should I just try to use household bleach?

My wife is probably going to be pregnant soon but needs the pool for therapy, so anyway to lower the amount of chemicals would be welcome. I am not someone who freaks out of things like this, but I also think its always better to minimize chemicals if I can.

Thanks for all your help.

[PoolDoc]

If your stabilizer is as high as we think, it's not over chlorinated -- it's actually under chlorinated! (See Best Guess chart)

Sometimes biofims form in spa piping, and is very hard to remove. Sustained very high chlorine levels will do it. But your stabilizer level may be so high that's not practical. In that case, it would be best to do a high chlorine just after filling, before adding any stabilizer. 10 - 15 ppm with no stabilizer for 24 hours should do it. If you add stabilizer afterwards, those levels won't be too high to swim in.

[milhouse19]

OK, Thanks. I do have the Taylor kit (Taylor Complete (high) DPD Test Kit K-2005). The problem is that the FC is off the chart (Leslie Pools also found the same thing). I've been trying to lower it, but without direct sunlight its not easy. The PH is a bit low (around 7.0). TA is in the 80s.

As for the heating, there are a few things that cause the expense. The run from the heater to the pool is about 45 feet and uses PVC, and the $1,000 quoted is for the month, which includes 30 days of running around 10 hours a day to keep it at 95 degrees. We only have a solar cover since the heavier covers which trap more heat are to heavy for my wife.

I did just check and the clarity has improved, but it sounds like it still make sense to dump the water and start over. I just pulled out my Endless pool documentation and they recommend 1/2 cup clorox per day for indoor pools. I will start there unless anyone has a better suggestion.

Thanks again.

[Watermom]

You have the Taylor K-2005. The one we recommend is the Taylor K-2006. They are not the same thing. You don't need to buy a whole new kit. If you just order the K-1515, that will give you the FAS-DPD component that your kit is lacking that will allow you to test high cl levels. You can find it in the Amazon link in my signature below.

[chem geek]

Ben is correct that I missed the posts about the Chlor-Brite. I now see the subsequent posts where you say you used Chlor-Brite. That is Dichlor where for every 10 ppm Free Chlorine (FC) it also increases Cyanuric Acid (CYA) by 9 ppm. So even with a low 0.5 ppm FC per day chlorine addition (and yours might be higher at 1 ppm), this is over 13 ppm CYA increase PER MONTH. So your CYA level may be very high and that makes the chlorine much less effective. I suspect you may have high Combined Chlorine (CC) as a result and that can be very irritating. After you get your Taylor K-2006 kit, you'll have proper readings for FC, CC, pH, TA, CH and CYA. We can then figure where to go from here, though I strongly suspect you'll need to replace more water to lower the CYA level.