Perplexed in MD

[openland]

Ok, so this is a little strange. This morning, before sunrise, my FC was 18, so to SLAM again to 24, I had to add 2 gal of Bleach. Tested again at 10:30am, and FC was 26 (52 drops with 10 ml sample)!

How is that possible? Am I doing the FAS-DPD test incorrectly? Maybe using too much powder?

 

[PoolStored]

How is that possible? Am I doing the FAS-DPD test incorrectly? Maybe using too much powder?

Pool size in pool math is too small. Increase by 500 gallons, repeat the add and test. Keep increasing pool size by 500 until your additions match expectations.
Testing error is also +/- .5
The ability for you to do 52 perfect drops is suspect also. Hold the bottle vertical and squeeze VERY gently so drops drop from their own weight. Don't rapid squeeze them off.
Not enough swirling

Could be any of these variables (maybe others). Are you using a speed stir?

 

[openland]

Pool size in pool math is too small. Increase by 500 gallons, repeat the add and test. Keep increasing pool size by 500 until your additions match expectations.
Testing error is also +/- .5
The ability for you to do 52 perfect drops is suspect also. Hold the bottle vertical and squeeze VERY gently so drops drop from their own weight. Don't rapid squeeze them off.
Not enough swirling

Could be any of these variables (maybe others). Are you using a speed stir?

Yes, I am using Smart Stir/Speed Stir.

 

[PoolStored]

Then likely one of the other three are your issue...

 

[openland]

Then likely one of the other three are your issue...

Could it be the size/amount of powder scoops for the test? I think I might have been using 2 heaping scoops (?)

I am reading this now: Water Testing Instructions - Further Reading

 

[PoolStored]

Could it be the size/amount of powder scoops for the test? I think I might have been using 2 heaping scoops (?)

No

 

[tikoh]

Ok, so this is a little strange. This morning, before sunrise, my FC was 18, so to SLAM again to 24, I had to add 2 gal of Bleach. Tested again at 10:30am, and FC was 26 (52 drops with 10 ml sample)!

How is that possible? Am I doing the FAS-DPD test incorrectly? Maybe using too much powder?

I had this problem with my pool too...It's difficult to know your exact pool volume, especially with pools the size of yours, mine, and PoolStored. I know that 36,000 is a slight over estimate for me, but that's what I use for estimating. I'd rather have a little chemical left over then not have enough. When it comes to actually dosing, I add slowly until I reach my target level. Your 34,000 gallons probably has about 800 square feet of surface area. If that's the case, then each inch of water level is about 500 gallons as well.

90% of the time you do not have to be perfect..if you're shooting for 6ppm chlorine and you hit 8 on accident, who cares? It'll come back down and you can try adding a little less next time. The time when it is important to be as close to perfect as you can is with the OCLT. If you're a little high, it's okay, but it's important to test and know exactly where you are so you can accurately measure your losses.

For everything but the OCLT, you can also use a 5ml sample and have every drop equal 1ppm. You'll use half as much reagent. Good for a quick check when you don't have to be perfect perfect.

 

[openland]

I had this problem with my pool too...It's difficult to know your exact pool volume, especially with pools the size of yours, mine, and PoolStored. I know that 36,000 is a slight over estimate for me, but that's what I use for estimating. I'd rather have a little chemical left over then not have enough. When it comes to actually dosing, I add slowly until I reach my target level. Your 34,000 gallons probably has about 800 square feet of surface area. If that's the case, then each inch of water level is about 500 gallons as well.

90% of the time you do not have to be perfect..if you're shooting for 6ppm chlorine and you hit 8 on accident, who cares? It'll come back down and you can try adding a little less next time. The time when it is important to be as close to perfect as you can is with the OCLT. If you're a little high, it's okay, but it's important to test and know exactly where you are so you can accurately measure your losses.

For everything but the OCLT, you can also use a 5ml sample and have every drop equal 1ppm. You'll use half as much reagent. Good for a quick check when you don't have to be perfect perfect.

It all makes sense. The OCLT matching is the most important ... nightFC - morningFC < 1.0

 

[openland]

I think I did it!! So now I just let the FC come down to a good level, right? At which point do I turn on my SWG?

 

[Newdude]

At which point do I turn on my SWG?

Once the FC has drifted down near target range. Dial it in on the high side of target range, or above. That way, if you goof, you aren't starting SLAM2.0.

Personally, I would hold SLAM another day. It's easy to do at this point and the insurance is invaluable.

 

[openland]

Once the FC has drifted down near target range. Dial it in on the high side of target range, or above. That way, if you goof, you aren't starting SLAM2.0.

Personally, I would hold SLAM another day. It's easy to do at this point and the insurance is invaluable.

I was going to set my FC target to 5.0.

Keeping SLAM for one more day sounds plausible. Should I do another OCLT? Or is it not necessary? I’m feeling a bit sleep-deprived at the moment

 

[Newdude]

Should I do another OCLT?

Yes. Get a 2nd opinion on your borderline pass with 1 FC lost overnight.

I was going to set my FC target to 5.0.

Please notice the leeway between your preferred target and minimum. Now notice the leeway between your target and SLAM level. Both leeways are safe. Which gives you more room for error ? Not getting it right on the first try could put you right back to square 1.

 

[openland]

Yes. Get a 2nd opinion on your borderline pass with 1 FC lost overnight.

View attachment 504791

Please notice the leeway between your preferred target and minimum. Now notice the leeway between your target and SLAM level. Both leeways are safe. Which gives you more room for error ? Not getting it right on the first try could put you right back to square 1.

I’m on it! Besides not getting enough sleep, apparently I’m running low on reagent too!

 

[openland]

I think I’m going to consider my SLAM process complete. The FC held steady during sunny yesterday (about 0.5 FC loss every 3-4 hours) and only smaller add-ons of Bleach were needed.

Marge Innovera signed off on it

 

[PoolStored]

Excellent!!! Congratulations!

 

[openland]

Excellent!!! Congratulations!

Excellent!!! Congratulations!

 

[openland]

Follow on questions (sorry, newbie here):

1. What should my target FC be? I was thinking 4.0?
2. How often should I test now (while I wait for FC level to come down to my target level)?
3. When should I turn my SWG on? I’m guessing I’ll need to do some math to figure out the % setting as well as pump runtime.
4. At what point do I start balancing other things - pH, CYA, CH, TA?

Thanks!

 

[PoolStored]

1. What should my target FC be? I was thinking 4.0?

FC/CYA Levels

2. How often should I test now (while I wait for FC level to come down to my target level)?

Basic Pool Care Schedule

This basic pool care schedule can guide you in creating your own pool care routine. Regular pool maintenance will keep your water sparkling!

www.troublefreepool.com

3. When should I turn my SWG on? I’m guessing I’ll need to do some math to figure out the % setting as well as pump runtime.

You run your pump to perform certain tasks. First, with a SWCG, is to generate your chlorine. So you find the lowest RPM that will close the flow switch on the SWCG, typically between 1200-1400 rpm. That should be set as your Pool Mode rpm. The run time is based on generating the chlorine. You determine that by what your pool FC needs are each day. Second reason to run the pump is to skim the surface. Again, you find the rpm needed for that. If higher than what is needed for the SWCG, you set it up to perform that, and the schedule for that is for how long you wish to skim the surface.

4. At what point do I start balancing other things - pH, CYA, CH, TA?

Now. Manage pH and leave TA alone. The rest anytime...follow pool care schedule.

 

[duraleigh]

Pool Care Basics Archives is the best place for answering beginner questions. It'll produce the answers you need to keep progressing

1. Depends on your CYA.............follow the FC/CYA chart
2. Daily for FC (for a while) Other parameters vary
3. When you get your CYA, etc. in the proper range
4. right now

 

[openland]

Status update.

Currently:
FC 7.5 (seems to be dropping about 1 ppm/day - it's been cool and cloudy here in MD)/CC 0.0
pH 7.4
CYA 60 (it was 50 after I was done with SLAM. Per PoolMath it asked for ~6lbs of Stabilizer to get to 70; I added 4lbs in a skimmer sock as I've read that it can take a bit for all the Stabilizer to get fully dissolved/distributed.)
SWG is not on

So according to the CYA/FC chart, I need to raise the CYA from 60 to 70 and then maintain FC of 5-10.
Questions:

1. Do I add 2 more lbs of Stabilizer to get CYA to 70 or do I wait a few days for the 4 lbs to get fully dissolved?
2. At what point do I turn my SWG on? My thinking was to wait until FC is 5.0
3. My target is to keep FC 5.0-6.0 and CYA 70. Does that seem reasonable?
4. At which point do I start messing with TA?

Again, thank you so much for responding - it's been a great help/reassurance. I must admit, I really like doing the chem tests, especially with SpeedStir. I think I am going to use SpeedStire for everything but pH and CYA tests.