Opening Pool First Time, Total Chlorine VERY high

Jul 12, 2017
This is my first spring opening our pool. We used the tarp style cover with weights around the edge(switching to safety cover for next winter). Temp. of water is about 45 degrees F. Water overall was pretty clean. Shallow end was clear and the deep end was cloudy but I could see the white drain at the bottom. There was a film of algae on the bottom of the pool. Did not have time yet to vacuum. After turning on the pump and letting it run, I took a sample and had the following results:

PH- 7.2

The next day I still had not vacuumed(no time yet), but I tested to see what the Chlorine was doing.

FC- 8 I added a little chlorine to get it back to 10 just to help with the cleaning process.

On Day 3 I finally vacuumed and backwashed my filter a few times. Water started to look even better. Deep end is still a little cloudy. Results:


FC is holding pretty well. Never dropping more than 2 ppm. My question now is what can I do to get the FC down and finish getting my pool crystal clear. I have a feeling I will need to shock it.... I am going to be out of town this weekend so it will have to wait until early next week. Please let me know what I should be doing next.

- - - Updated - - -

I forgot to give my CYA results. I know the water is cold and the results may not be accurate, but my CYA on all 3 days was 60.


Mod Squad
LifeTime Supporter
TFP Expert
Apr 18, 2010
East Texas
I'd do an overnight chlorine loss test and see if that indicates a need to perform a full SLAM. FC will drop on it's own....especially if your SWG hasn't kicked in yet.
Apr 16, 2016
Central Florida
Thank you for posting your test results!!! Very helpful indeed. A couple things:

1. I think performing an is a fine path, but ultimately an unnecessary delay since you can see a good quantity of algae and have cloudy water with CC verifying the problems
2. You would experience the best results from doing as close to a full as your schedule allows, as soon as reasonably possible, even if interrupted by your weekend. No worries, your efforts between now and then will still very much count. Even if you don't do it now, the algae still needs to be held down, which will present as an increased FC demand, so keep up your great job of maintaining the 7-10 FC for your 60 CYA. Falling under that will let your algae bloom fully very fast. No matter what you choose, you'll see benefits from bringing FC up to as high as 24 as frequently as you can ([FC/CYA][/FC/CYA])
3. Instead of posting FC & TC, please post FC and CC.
4. It is actually best not to backwash before you need to, as a slightly dirty sand filter actually catches the finer dead algae particles that present as cloudiness. Unless you're not going to be home to check it, wait to backwash until the PSI reading is 25% higher than your starting clean pressure.
5. Great job on the vacuuming, but if you have a brush head, please brush the pool too. Algae forms a bio-film that somewhat defends it from chlorine, and brushing tears it open enough to really help the chlorine get in there and work!

For a quick refresher of CC:
Chlorine Drop test
1. Rinse and fill the “Chlorine only” graduated cylinder to the 10mL mark
2. Add ONE heaping scoop of the R-870 powder and swirl to mix. (It may not all dissolve….don’t worry) The solution will turn pink. (unless you have no chlorine)
3. Next, carefully add R-871 solution one drop at a time. Count each drop and swirl until the solution turns back to clear. Multiply the number of drops you added times .5 (14 drops X .5 = 7ppm)
4. Record your results as FC (free chlorine)
5. To test for Combined Chloramines, add 5 drops of R-0003 to the solution and swirl. If it remains clear, you have no CC’s. If it returns back to pink, add R-0871 as before, counting and swirling between each drop. Once the solution returns clear, multiply the added drops times .5 again…..this will be your CC reading. Record it. The total of FC and CC should be recorded as TC (total chlorine)