Help! SWG and chlorine level

[Ngosch]

Hi there,

I’ve been having really good luck with my new kit and numbers. Today, I opened the pool cover and it looked a little cloudy. I went to work and came back and tested it and all of a sudden the FC level is 0.5. I posted all my numbers from today. I’ve had the output set on about 10% and it’s been giving me readings around 5.5. I did notice the other day it was lower and then should have checked it yesterday but it was a nasty day so didn’t even open it. I am going to get some bleach, but can anyone give me any idea what happened??

 

[Mdragger88]

At some point your fc must have dipped below minimum for your cya somewhere in the pool. A high uv/hotter day is all it takes sometimes which is why I like riding at 10% of my cya so there’s always a good buffer.
To confirm it’s algae you can do an
Overnight Chlorine Loss Test or you could just go straight to the
SLAM Process.
You mentioned a cover- you may want to clean that.

 

[Mdragger88]

Also the swg % / run time needs to be adjusted with the season- more in the peak of the season, less in the shoulder seasons. After slam is done you need to increase your % some.
If you’re running the swg around the clock 10% only yields 1.2ppm per day. Average fc loss in an algae free pool is 2-5 ppm/day depending upon the season & conditions.

 

[Ngosch]

Thank you! I just added bleach and I’ll turn the output back up to around 50 and start there.

 

[Mdragger88]

Do the
Overnight Chlorine Loss Test
Be sure the swg is off during the test.

 

[Ngosch]

Ok, I’ll do that tonight. I was an idiot and used “splash less” bleach so now I have white foam everywhere.

 

[Mdragger88]

It should dissipate so long as you don’t use any more.
Remember, none with cloromax,“fabric protection, or scents either.
The best bet for unadulterated stuff is just getting dedicated pool chlorinating liquid.

 

[Ngosch]

So 28 is the number I got on the calculator for my FC. Once I do the overnight test and I know I am finished, how long will it take my FC to come down to a reasonable number?

 

[Newdude]

My pull it from wherst the sun doesn't shine guess is you'll lose 5 or so ppm a day the first couple days because FC burns off faster at a high FC, and really starts to be noticeable in the 20s. Then it will taper down to losing 1 to 2 ppm a day once it's closer to 10. So, a little over a week ?

 

[Ngosch]

Dang…when would it be safe to swim? Around 10?

 

[Mdragger88]

For a successful SLAM Process
you need to continue to MAINTAIN Slam level fc for your cya as often as possible (multiple times per day is best) until you meet ALL 3 end of slam criteria-

You are done when:

CC is 0.5 or lower;
You pass an Overnight Chlorine Loss Test
AND
the water is clear.
(Crystal Clear w/no algae dead or alive)

*Check & scrub every nook & cranny where algae may hide (light niches, steps, drain covers, ladder handrails, skimmer throats/weirs, abandoned lines, autofill, overflow drains, etc.)
*If water can go there, algae can thrive there.
*Run slam level water through all water features & lines for at least a couple hours a day during the SLAM Process.
*Brush & or vac daily (this breaks up biofilms that algae uses to protect itself from chlorine)
*Backwash/clean filter when pressure rises 25%over clean pressure.

It could take a day or two or three for fc levels to come down- really depends on the sun.

It is safe to swim with fc levels anywhere between minimum & slam level for your cya so long as you can see the bottom of the deep end of the pool for swimmer safety.

 

[JupiterFL]

So 28 is the number I got on the calculator for my FC. Once I do the overnight test and I know I am finished, how long will it take my FC to come down to a reasonable number?

I dont think the advice was to go up to SLAM level now. It was to do the OCLT to see if you need to SLAM.

 

[Newdude]

I dont think the advice was to go up to SLAM level now. It was to do the OCLT to see if you need to SLAM.

It was to OCLT or go right to SLAM and with any luck, have a quick one that passes the first night.

There's no harm in going for the throat if there's any inkling of an issue. If it turns out it was necessary, you're 12+ hours into the battle by tomorrow.

 

[Ngosch]

That was my thought. It was cloudy and had a greenish tint so I was pretty sure that was the problem. I didn’t want to let it sit another night. The FC dropped by 3 overnight so I’ll keep treating it throughout the day and hopefully it will pass tonight. It looks much better this morning already.

 

[Newdude]

The FC dropped by 3 overnight

The you DEFINITELY made the right call and started today with a leg up in the battle.

One common theme I've seen play out too many times to count, is that rookies sit around thinking of reasons they don't need to SLAM. They are usually gifted a swamp for their (lack of) efforts. Pros SLAM first and ask questions later. If it turns out to have been unnecessary, it's over the first night and was far easier than the other outcome.

Keep us posted.

 

[Ngosch]

I was so close this morning! I checked twice and got -2.0 and -1.5 a half hour apart. Guess I’ll stay after it another day. Kids want to swim today.

 

[Mdragger88]

Getting closer! How’s it looking? Also, add your filter to your signature

 

[mknauss]

Kids want to swim today.

Let them. As long as you can see the bottom of the deep end. SLAM level FC is fine to swim in.

 

[JamesW]

Any more green hair?

 

[Mdragger88]

Any more green hair?

Forgot about that!