Water Balanced But Not Looking Great

[mculik5]

Relatively new pool owner here, using the BBB method for a 29K gallon vinyl pool. The pool was looking great prior to the holiday weekend. The water was clear and well balanced, I had added some DE to our sand filter, vacuumed it several times (with our Doheny Discovery), etc.

Over the holiday weekend, we had a light swimmer load - 2 kids and 3 adults. After the weekend, I backwashed the filter, mostly to remove the DE, as it was impacting my pump flow rates and didn't make a noticeable difference in water clarity (to my eyes, at least).

Since the weekend, I've noticed two things:

1. On 7/6, a little bit of algae growing on the pool walls. Not much, and seems to be be better now, but there is still some there. When brushed, it appears greenish-brown in the water.
2. In generally, the water is looking a bit cloudy/matte. Not terrible by any measure, but not the crystal clear, sparkly water like it was before the holiday weekend.

Here are my recent test results, using the TF-100 kit:

Date	Temp	FC	CC	TC	CYA	TA	pH	Added after testing
6/30/2017	--	1.5	0	1.5	--	--	7.8	2 jugs bleach
7/2/2017	81	2	0.5	2.5	50	100	7.8	2 jugs bleach
7/6/2017	--	2	0	2	50	110	8	3 jugs bleach (b/c of algae), 1/2 gal muriatic acid
7/8/2017	--	5.5	0.5	6	50	110	7.5	none

Any tips to help eliminate the algae and get back to beautiful water?

Thanks.

 

[Richard320]

Yes. SLAM Process

 

[mculik5]

Thanks, Richard!

I had to get bleach, so I didn't start slamming the pool until the evening of July 9. I used Pool Math to figure out how much bleach to add to bring the FC level to 16. I waited a few hours, then did a chlorine test, which showed FC 15.5. I decided to do an OCLT for the heck of it, thinking lots of bleach would be converted overnight dealing with the algae and whatever is in the pool that is making the water cloudy.

I checked the pool the morning of July 10, before the sun came up. FC 15.5...no chlorine lost overnight... I didn't add any bleach, and went to work. Checked the pool when I got home. FC 9.5, so I added enough bleach to raise the level to 16 again.

I checked the pool again this morning (7/11), and it was still showing FC 16. Again, no chlorine lost overnight...

The algae I mentioned before is still there (has NOT spread), and the water is still cloudy/matte. I've been running the vacuum each day, and from a debris perspective (leaves, dirt, etc.), the pool is pristine. The water is still "blue," and I can still see the bottom in the deep end, but the water is cloudy... For what it's worth, I've been running the pump 24 hours/day - 22 hours at low speed, and 2 hours at high speed. I have a flow meter, and based on that, I'm turning the pool over once per day. Also, I have a digital pH meter that said the pH was 7.66 as of this morning.

Finally, regarding target FC 16 for shock level vs. FC 20, my CYA readings fluctuate between 40 and 50 (because of my subjectivity about whether the dot is visible or not). When I tested before starting the slam, it tested at 40, so I went with that since it saves a little bleach.

What do you think is going on? Continue slamming, or are there other things I should consider?

Thanks.