SLAM Likely Needed

[Jean-ji]

We have been battling chlorine loss. We are in FL with either full sun or drenching rains the past two weeks.

CYA was 50 and we added stabilizer Saturday morning. It was mostly dissolved that evening and the sock was empty the next morning. This morning CYA reads 60.

Last evening we had 5.0 FC and this morning it was 3. I used the DPD kit from the Taylor K1004 we had. I can read the pink scale on it better than the yellow one in TF100.

Edited, I posted incorrectly first time.
I then used the weekly chlorine drop test also this morning:
FC 2.5
CC 0.5
TC 2.0

Do I need to do the overnight chlorine loss test with the drop chlorine test for more accuracy?

Water is clear to the eye. We started dialing up the SWG the middle of last week.

My CYA may still be going up too. My first instinct is to SLAM now, but should I wait for the more accurate overnight test and another CYA tomorrow morning? Advice please.

 

[mknauss]

I suggest always using the FAS-DPD test for FC. The color comparator ones are for telling you you have chlorine or not. Definitely not accurate.

Use your predicted CYA for SLAM level today. The CC of 2 tells you something is in the water.

 

[Jean-ji]

My error in posting wrong numbers.
This morning’s drop chlorine test from the TF 100 is:

FC 2.5
CC .5
TC 2.0

This is why I’m questioning a slam or not, especially with a CYA reading 36 hours from fully adding stabilizer. Will it go higher?

I retested with the TF 100 weekly drop test again, after adding enough chlorine to bring FC target to 5. I waited one hour after adding chlorine.

FC 5.0
CC .5
TC 4.5

 

[mknauss]

Up to you. Your FC has been below minimum for any CYA. So monitor the water clarity.

 

[Jean-ji]

Thank you for the help. I think I’ll wait to do the overnight test properly, and also check CYA tomorrow and then do the SLAM if the FC loss is more than 1.0. It probably needs to be done, but I’m no better than a pool store if I’m doing things without the numbers being there to back up what I’m doing. I can wait a day to see where my CYA is and if the FC loss is real.

 

[Jean-ji]

Bad news (expected) and some good news

The OCLT failed.

Last evening TC was 7.0
This morning TC was 3.5

CC was .5 both times.
Water is clear, the bottom is clear, brushing doesn’t stir up anything. The water isn’t quite as sparkly, but I wasn’t sure if that was true or imagination.

The good news is the CYA was 70 yesterday afternoon, up from 50 after adding stabilizer on Saturday. I had corrected the FC in the morning and ended up with more than I started with by the afternoon. That was a first. We had the SWG up to 50%, so after the SLAM and when we turn it on again, we will tweak that.

I am a bit freaked out by having to go from 3.5 FC to 28. That will require 224 oz for a 7500 gallon pool to start. Is that correct? I’m using 10.5% bleach from the pool store. I’m planning on buying 2 yellow jugs at 2.5 gallons for 5 total to start. I have a gallon already and I’ll go from there.