High Free Chorline

by Bernie

My name is Bernie and I’ve watched 2 of your videos now and thank you they where very helpful. I just took over the management of a hotel and am s novice to this pool stuff. I am not yet a certified pool operator but learning.

My trouble started a couple weeks ago with a large family that rented the pool and then another large party with 15+ kids for 2 days on New years eve. Then I added 2 chlorine tabs that I broke up with a hammer and a bag of shock after they left which was wrong I should of tested first I have a 30.000 gallon pool heated indoors as I am in Iowa.

And my free choline is high. Here’s what I got rockin 84 degrees, covered, test 4 times a day w/ Taylor k-2006c test kit Manual free was at 9.0 added chem-out now at 6.4 Manual total is .2 Ph. 7.5 Auto readings are: total 1.0 Orp 751 Ph7.6 How do you lower free chlorine with changing everything else?

Thanks for the question Bernie

First as a side note you can check with your local and state laws in regards of having a Certified Pool Operator on the premises. I was the pool operator for the Y in Oregon and the state law required to have a CPO for a pool 2100 sq. ft and over.

There are a few things going on here so I'll start with the chlorine tabs. These are a stabilized form of chlorine and will raise the CYA/stabilizer. For every 10ppm of chlorine added with Trichlor tabs you'll raise the CYA by 6ppm. The range for CYA is 30 - 50ppm. The only way to reduce the CYA is a partial drain and refill. If you go back to YouTube and watch the 5 part series of clearing up a green pool you'll notice the CYA was at 90 - 100ppm. I did a partial drain/refill to get the CYA down to 30ppm. Another pool I cleared up had no CYA so I added about 3 lbs. to bring it to 30ppm. Two completely different approaches to clearing up a green pool.

Next is the bag of shock. You need to be careful with "shock". Although several different bags say shock, they are different. Most of the time they're either calcium hypochlorite which is unstabilized or Trichlor or Dichlor shock which is stabilized. They're marketed the same way but the latter will raise the CYA very quickly. Unsuspecting pool owners shock their pools each week with a 4:1 or 6:1 (Thrichlor or Dichlor) shock but what they're doing is raising the CYA and within a couple of months their pools turn green and they have no idea why.

There are a few ways
to reduce the chlorine. First is time. 2nd is dilution by a partial water change. 3rd is usage and 4th is a product called Thiosulfate. If you look in your test kit for the TA you'll see R-0007. This is Thiosulfate which is a chlorine neutralizer. This is powerful stuff and should only be used as a last resort. I used this at the Y when I had to shock the pool. The FC was around 12 - 15ppm and I had to get it down to around 6ppm for the swimmers. If it's over-used it can mess up the other readings (TA and pH) and cause then to bottom out. I don't know why but it does.

Your FC reading is at 6.4 which is acceptable. A bit high but nothing to worry about. If you need to shock I'd encourage you to use liquid chlorine. It's 1 gallon to bring the FC up to 10 - 11ppm per 10k gallons. If you're pool is 30k gallons you'd use 3 gallons.

The only time you'd need to shock is when the combined chlorine/chloramines/CC get to 0.6ppm or above for 3 consecutive days. If you know there's going to be a large party or lots of people you can simply take the readings and add chlorine to bring the FC up to 5 - 6ppm. Do this a few hours ahead to allow the filter to treat the water. I ran the Y pool at 4 - 5ppm and everything was fine, and this was with 5k swimmers per month.

To save you a headache you can require swimmers to take a hot soapy shower before swimming. This will reduce the oils/sweat going into the filter and clogging it up. Water will always take the path of least resistance. The water will end up going around the inside of the filter and be returned back to the pool and unfiltered water. Not good.

With an indoor pool be aware of proper fresh air intake and exhaust. This will keep the chlorine smell down and keep the walls from getting wet and possible moldy. You probably need to run the filter 24/7 being this is a commercial pool so I'd encourage you to check with the state laws on that.

One thing I forgot. You mentioned Chem-Out. Is this Bioguard Chem-Out? If so this is nothing more than inorganic salt according the MSDS.

If you feel your situation is more complex than this, I do phone consultations for a donation of your choice. It makes things go much faster and many people have found it extremely beneficial, saving them time and money in the long run. All your questions will be answered. I have nothing to sell you so you know I'm not bias.

Pool Consultation


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