Millionth SLAM but not quitting

[SW Pool Owner]

I've done SLAM and passed the OCLT a few times now. I've even done the OCLT an extra day and passed. I have another algae bloom, and I've started SLAM again. My FC was around 20 for SLAM and dropped to 7 at the lowest with a CYA of 50, so I have a few ideas where this algae is coming from.

1) I have a large sakura shrub with a branch of leaves that has grown and has a few leaves touching the water, I didn't really pay much attention to this but if this is the algae source you guys can shame me now

2) There were small lines of green on the skimmer doors, I brushed those down until the lines were gone. I don't think this is a source of algae, maybe dirt? But I just brushed it down now

3) I have not checked behind the light fixtures, actually one of my fixtures the plastic holder to screw in the light is broken I think, I need to get into the water with goggles and take a look. When the light popped out the light didnt have any algae, and the liner behind the light is ripped. If I'm supposed to clean behind the light, do I just stick the brush in there and brush the back?

4) Maybe im not running the pump long enough? The sun is hitting the pool early around 9AM and I have the pump starting at 10AM running until 6PM at night, sunset is around 8:30

 

[PoolGate]

What chlorine level are you normally maintaining? It sounds to me like you are running right at the low end of the range which is a sure bet for algae.

 

[SW Pool Owner]

Per here Free Chlorine and Cyanuric Acid Relationship Explained says 3-8 is maintained. The lowest I dropped to was 7

 

[PoolGate]

I would keep a closer eye on chlorine level. You could dump a box of algae in my pool and it would never result in an outbreak. Test your CYA again to ensure you are reading the proper level.

Also to clarify, you are keeping a level of 7 as your normal FC correct? You have a SWG but are not running your pool much, what is the chlorine output of that SWG? 8 hours doesn't seem like enough even at 100% output. I run my pump 24x7 at 55% SWG level.

 

[Mdragger88]

When you quit slam the last time was the pool crystal clear with no recurring algae (dead or alive)?
How Clear is TFP Clear?
The oclt is only one of the 3 end of slam criteria.

 

[SW Pool Owner]

Last time I passed OCLT two days in a row. The day after the first OCLT I saw dead algae. After 2nd OCLT I saw the faintest hint of dead algae, which I assumed was pollen. I mean I guess I can hold OCLT for 3 nights?

 

[PoolGate]

Are you manually adding chlorine or is it just your SWG that provides it? I'm asking just for normal run not slam.

 

[duraleigh]

I mean I guess I can hold OCLT for 3 nights?

There's no point. The OCLT is intended as a one time overnight test to gauge chlorine consumption from organics in your pool.

Running that test more than once is like wearing a belt with suspenders. It only reproves what has already been proven

 

[SW Pool Owner]

1.52/lb is the output, however I tested the FC every two days and it was coming down from the SLAM. With the SWG running about 12 hours 100% I was able to add 1 ppm of FC the next day. The FC never dropped below 7, only thing I can think of is the sun burned all the FC in a corner of the pool and the algae grew in that time.

 

[Mdragger88]

Last time I passed OCLT two days in a row. The day after the first OCLT I saw dead algae. After 2nd OCLT I saw the faintest hint of dead algae, which I assumed was pollen. I mean I guess I can hold OCLT for 3 nights?

You should hold slam level fc until you have passed ALL 3 end of slam criteria-
That’s why there’s 3 criteria not just 1.
Until the pool is crystal clear with no recurring algae (dead or alive) you don’t really need to do the Overnight Chlorine Loss Test although passing the oclt is a helpful indicator it of where you stand before you are clear passing it alone doesn’t mean you just stop slam.