How did this happen? Algea Explosion

[Tommygarry1]

Hi everybody. I woke up to a green and cloudy pool this morning after flash flood type rain yesterday. I have been taking care of my pool for the past three summers and this has never happened. The last time this did happen was the first year I owned this house and I was not taking care of the pool. It happened twice that summer so I decided to educate myself.

Even the last three summers, after crazy rainstorms. I have never woken up to anything but a clear pool.

I am attaching a picture of the pool, and a snapshot of my last two chemical readings. The bottom chemical reading is from yesterday morning before any rain. The top reading is from this morning.

Please note that the CYA that I am reporting is from the pool store. When I test my CYA I get 40 to 50 using the taylor test. I have no confidence in my ability to do the dot test and I have read all the articles and looked at the photos.

Also, I do notice that my pool water looks a lot more crystal clear with my chlorine levels around 6, which leads me to believe that the CYA level from the pool store is the correct reading. I've taken my water to the pool store multiple times and the CYA test was consistent, it even increased proportionally based on a CYA add that I did at one point

No clue how a FC levels of 7.5 and balanced water could not handle a rain storm.

Would love to hear anyone's thoughts. Thank you.

 

[PoolGate]

Well.... what can you do. Maybe do an OCLT and prepare to start the SLAM process. Also I suggest you get the standard/reference CYA 50ppm sample solution. This way you'll see what it looks like.

R-7065 CYA Standard 50ppm (2oz)

tftestkits.net

 

[duraleigh]

Any chance the rainwater ran INTO your pool?

 

[Tommygarry1]

Any chance the rainwater ran INTO your pool?

Yes, as my pool is at the bottom of my backyard which has a hill. The pool is surrounded by landscaping. They're definitely is runoff, as I did see dirt and debris on the steps. To be fair, I did also see that happening after storms the past three seasons where I would have some debris, but still had clear water.

 

[PoolGate]

For the future I would see what kind of draining can be integrated into your backyard to prevent water running in the pool. Maybe some French drains.

 

[duraleigh]

Runoff INTO your pool is the death knell for clarity.

Not much to do except run your pump[ 24/7, keep chlorine levels adequate, brush floor and walls often. That DE filter may plug up pretty easiy........watch your psi and clean the filter if it goes up 25%

I see no reason to SLAM until your pool gets cleaner and then perform an OCLT. I bet you pass but you still need clarity.

Keep filtering but PLEASE do NOT use clarifier or floc You may make it worse.

 

[Tommygarry1]

Thank you. I agree as this is pretty much what my pool looks like when I open it up and I usually add 2 or 3 lbs of Chlor Brite to get a little CYA kick and the pool is clear in 3 to 4 days. I did already add liquid chlorine, so too late on that, but I will just run the pump and continue to backwash. I just backwashed this morning as the psi jumped from baseline of 15 to 30 in a few hours. That usually happens 3 or 4 times in the first week when I open, so I anticipate I will need to backwash 3 more times over the next few days until it clears up. When my pool is clean, it takes weeks -- usually over a month for the psi to jump 25%.

 

[Tommygarry1]

Morning update. I can do a CYA test now. Big difference doing dot test outside. After 24 hours of filtering and 5 backwashes, I can see the main drains and the water is much better. Will be crystal by this afternoon. Also passed OCLT. Going to be hot today so glad the pool will be in use. Yesterday was a lost day.