Problems Testing for FC after SLAM

[mf7365]

SO I started a SLAM this morning after opening pool and noticing my water starting to turn green. I have a SWG 26700 gal.
pH-7.2,
TA-80,
CYA 50-60,

Using my Taylor 2006 I cant get the water to go from pink to colorless. At the 25ml test after 15 drops its still dark red. Same thing at the 10ml test.

Also, I had to bring the CYA up from below 20. Everything says not to backwash for a week, but it also says to backwash frequently while slamming if PSI goes up enough to warrant. I run 14/15psi clean and am at 18/19psi right now. Do I backwash or not?

 

[jblizzle]

Welcome to TFP!!!

How much chlorine did you add? Are you using PoolMath?

Sounds like the FC level is high and you are not counting enough drops. 15 drops is only a FC of 7.5 ... and with a CYA of 60ppm, you need to maintain the FC level at 24ppm ... that is 48 drops with a 10ml sample.

We recommend backwashing when the pressure rises 20-25% over the clean pressure ... you are there and the CYA appears to already be showing on your test.

You also should have waited until after the SLAM before raising your CYA so high for the SWG.

 

[mf7365]

I am using pool math. I was at 0 for CYA when I opened the pool and accidently over shot my goal of 30. At my closer to 50 CYA it is calling for a shock FC of 20. So basically, I need to just keep adding the drops. I had stopped thinking I was missing something after 15 drops.

And I can backwash without it negatively affecting the CYA now since it is definitely registering, correct?

 

[jblizzle]

Correct to both.

FYI, we recommend putting the CYA in a sock in the skimmer and not pouring it into the filter ... so you know when it is dissolved and not lost if you backwash.

 

[mf7365]

I did a sock with the CYA. I think my initial CYA level may have been off a little, so I was going from 0 when it was actually higher. But since I have a SWG I'll need it at around 70ppm so at least I dont have as far to raise now. My FC was 24 which is dead on for a CYA at 60 which it was when I rechecked. Also when I checked for CC it barely changed from clear after 5 drops. And 2 drops of 0871 cleared it totally. So if I keep at at this level, check again this evening and tomorrow morning get a CC of .5 I'm clear correct? The water had just turned a hazy green when we started this morning. Nothing bright and nothing sticking. We have been doing everything on schedule.

 

[jblizzle]

You just need to make sure you pass all 3 criteria to stop the SLAM process.

 

[duraleigh]

That hazy green you describe should have nothing to do with your SLAM and shouldn't be there. Got a pic?