SWG Manual FC rec vs TFP

[jdavided]

Hello everyone, I have a question about the FC level recommended by the Jandy SWG operating inx vs what is prescribed here at TFP. I have been an avid reader since pre-construction (unfortunately didn't find the time to do a construction thread). Anyway, Jandy (as most of you probably know) recommends a FC level of 3.0 PPM for their SWG with CYA @ 50-75 while the ChemGeek chart prescribes FC at 8 for CYA @ 70. Jandy further claims FC above 3.0 harms pool metals?

I have added chemicals based on pool math to bring current #'s to-

• FC @ 8.2 (added liquid chlorine, 10% to raise to TFP rec)
• CC @ 0
• PH @ 7.4 (overdosing muratic acid b/c of new plaster/creeps back to 7.8 in a day or two)
• CH @ 400
• TA @ 70
• CYA @ 70 (best I can tell from the Taylor kit!)
• Salt cell reading 3.0-3.5

My questions-

1. How do I square the Jandy FC vs the TFP?
2. Can my salt cell ever get the FC to the 5.1 min FC much less 8?
3. Do I need to add salt to raise FC
4. I assume most pool owners don't add liquid chlorine to their SWG pool to hit these #'s?

I plan to make the donation to this website as it has been a fantastic resource! Thanks everyone and I really appreciate your continued insight!

 

[mknauss]

Welcome to the forum! :handshake:

1. Pool industry does not fully embrace the FC/CYA relationship. That relationship has proven to maintain a clean, sanitary pool. The active chlorine in pool water with a CYA of 70 ppm and FC of 3 ppm is a fraction of what a public pool has with 0 CYA and 2 ppm FC
2. Your SWCG is designed to create the chlorine needed to maintain your FC at your target level. Most pools lose 2-4 ppm of FC per day. That is what the SWCG needs to create.
3. Additional salt does not raise the amount of chlorine the SWCG creates. As long as the salt level is adequate for the SWCG to operate, its ability to create chlorine is stable.
4. Absolutely we use liquid chlorine. To raise your FC to target level use LC. If you have a pool party with lots of bathers, use LC to boost FC.

You can approximate how your setting for the SWCG should be . See SWG Run Time Calculator

 

[Deb04]

SWG owners don’t add LC on a daily basis. That’s the huge benefit of a SWG. But, I do use it at the beginning of the year to get the FC up to the level I want so the SWG can take over. I also use it to boost if/when needed, like mknauss said.

 

[jdavided]

Ok, that makes total sense! I appreciate your help!

 

[SpringPool]

I just put in the PLC1400 myself. Make sure to get a the salt test kit Taylor K-1766.

I had had brand new salt test strips that were all off by 1000 ppm.

Take a look at my signature and the cl/cya chart

For a swcg the recommended level of chlorine is 5 with a minimum of 3 not the 8 you quoted.

I’ve found running my vsp pump at a low rpm (about 1000) longer and the swcg at a lower output give the pool a Consant amount of chlorine to keep my pool right around 5. I increase speed of the pump twice a day to help with skimming but the pump runs for 12 hours a day and saves a lot in electric usage.

It took about a week in the hot Texas sun to figure out the correct swcg percentage.

 

[jdavided]

Thanks for the input, SpringPool! I have actually been using chem geeks chart found @ http://www.troublefreepool.com/threads/2177-Chlorine-CYA-Chart . After reading about both of them, it seems the one you are using is best guess vs one that was put to together based on chemistry. I am sure either will keep the folks healthy though!

 

[Propbndr]

That link and the fc levels you are quoting are for a non-SWG pool. The cya chart in Pool School is the one you want for a SWG pool. Pool math also has to be setup for SWG vs chlorine pool.

 

[SpringPool]

Thanks for the input, SpringPool! I have actually been using chem geeks chart found @ http://www.troublefreepool.com/threads/2177-Chlorine-CYA-Chart . After reading about both of them, it seems the one you are using is best guess vs one that was put to together based on chemistry. I am sure either will keep the folks healthy though!

Thank you for the link. I knew the pool school chart came from a thread I just never looked at it. If you read the edit in the thread the pool school link is a version of the chart just with numbers rounded off.

Also I just read the foot notes and it talks about having a swcg and that you want your FC to be 4.5% of your cya. I knew there was basis for this in the simplified chart but now I know why.

So as Steve mentioned with a swcg you want to use the second chart not the first.