Cannot maintain FC with SWG

[swbill]

I'm new to this forum, sorry if this has been asked before.
We changed to salt water this past May and have had problem maintaining FC. Had the pool company come out and check the SWG, they said it was producing and issue was our chemistry. I told them I use a Taylor test kit and everything is within recommended levels (also had water checked at pinch penny and leslies pools).
Salt 3000
PH 7.4
TA 120
CYA 80
CH 300
Phosphates less than 100
Water temp 84 (we live in Florida)
Pool tech then said we have algae problem even though water was clear. We did have the beginning of black algae. Since the pool surface was 14yrs old and we really did not like it, we decided to resurface with pebble sheen. All traces of black algae were removed prior to resurfacing. Per Pebble TEC instructions, pool cured for 30 days without salt, using just chlorine. There was no problem keep FC during that period. After the 30 days, we converted back to salt and within days the FC disappeared. We tried running pump 7/24 at 90% (Goldine Turbo T15 cell), still no FC. I took the cell to Pinch a penny to have it tested, result said replace the cell. Called pool company again, they replaced the cell and left. Next day, still no FC. I checked chlorine level at each return jet, shows about 1.5ppm. I also loosened the output connection on the Turbo cell and tested the water, it showed about the same. We ran the pump 9am - 9pm and Midnight to 6am each day, still no FC. Don't know where to go from here.

 

[benavidescj]

Hi swbill and welcome to TFP!

What size is your pool?

 

[benavidescj]

swbill, now that I think about it, you should use bleach to get your pool under control first and then troubleshoot the SWG. You need to determine if you currently have organics in the water by doing the overnight FC test. If the overnight FC test shows you have no organics and your FC level is as recommended in Pool School then you can troubleshoot the SWG. Keep bleach handy in case you really are not producing CL with the SWG so you can maintain the FC. If you are fighting algae it will be difficut to troubleshoot the SWG problem.

 

[swbill]

Thanks all, pool is 12,000 gal. Not sure how I can have algae since FC was maintained at 3 - 4 while pool was curing for 30 days. FC dropped only after I stopped using chlorine and started the SWG. I checked the pool last night about 11pm with pool light on, it was absolutely crystal clear.

 

[benavidescj]

Sounds like you still have a SWG problem, maybe the experts can answer. I just don't want you to get an algae problem while you are troubleshooting the SWG.

 

[Guest]

Are you brushing the pool, and have you done the overnight test?

People get lulled in to a false sense of security on SWCG and feel like they will do it all. Some of that can be blamed on the salesperson that oversells what it truly can do. Just because you have a SWCG does not mean that you will be able to maintain proper FC levels or won't need to add liquid occasionally.

I don't have any info close by on GoldLine, but I am assuming ( ) you have a 15,000 gallon rated cell on your pool. Whoever decided to use that small of a cell needs to be educated a bit more, as that is too small (IMHO) and will need to work too hard to work in your pool. Sun, warmer water and bather load will all consume chlorine, and you may just not be keeping up.

 

[swbill]

Simicrintz, I have a Kreepy that I run 3 or 4 days a week, plus I brush the sides at least once a week. The SWG cell is rated by Goldine for up to 40,000 gals. The pool is only used for a few hours on weekends and it is only my wife and I. I have not done the overnight test, will be going to pool store today to purchase the FAS-DPD kit. Also, my filter is a completely new Pentair unit, installed right after pool was resurfaced. The filter in it was replaced a week after the pool was refilled, there was so much gunk in it from the resurfacing that it really could not be cleaned. I clean the filter every weekend and have not seen any sign of algae in it.

 

[Bama Rambler]

Just an interjection here.

Lots of people trying to buy the FAS-DPD test kit at a retail store have been sold the DPD (not FAS) kit and have been told that it's the same. It's Not!! Don't be fooled into buying the DPD kit. Most pool stores don't stock the FAS-DPD and since they want to sell you something they try and get you to buy the DPD.

 

[DBfan187]

add chlorine to pool

 

[swbill]

Thanks bama, I did my research here on this site so no one is going to steer me wrong.

 

[dschlic1]

I highly recomment that you perform the over night chlorine loss test. I am also in Florida, and I can tell you that a clear pool can and will have organics int it! The only reliable way to tell is to perform the over night chlrine loss test.

 

[swbill]

OK, did the FAS-DPD test using the 25ml sample. Result this morning was the same as last night; added DPD powder, water never turned pink even after 4 dippers. Added 5 drops reagent #3, turned slightly pink. Turned clear after 1 drop R-0871. Also did the DPD chlorine test for FC and TC at each return jet last night and this morning, less than .5ppm. SWG set at 90%.
Should I add liquid chlorine today to bring up FC level and repeat test again?

 

[Bama Rambler]

Do you have an OTO chlorine test? If so use it just for verification.

Having said that, you definitely should add chlorine right now. You need to add 2 large (182oz) jugs of bleach then wait and hour and test it to see what FC you have. 2 jugs should bring you to 15ppm FC.

Then you should perform the OCLT (overnight chlorine loss test) tonight. Test after the sun has gone down and again before it comes up. That'll confirm/deny the presence of any organics in the water affecting the output of the SWCG.

Once that's done, come back and let us know what the results are. Then we'll tackle the SWCG issue again.

 

[dmanb2b]

Also, if you could post a full set of test results, it would be very helpful for us to assist you. As i'm reading the above posts, i'm wondering what you're CYA level is?

To me it's 3 things that could be causing your issue:

1) SWG is not generating chlorine
2) SWG is making chlorine but it's getting used up to fast due to lack of CYA
3) SWG is making chlorine, CYA is present, but chlorine is being consumed by organics.

Hope this helps!

 

[swbill]

I added the chlorine this afternoon. Before I added it, I ran tests again;
Salt 3100
Water temp 84
FC 0
CC 0
PH 7.4
TA 130
CH 300
CYA 70
Phosphates less than 100
I could not test chlorine after adding it, will do it after work.

 

[benavidescj]

swbill, you need to test at sunset and then again at sunrise and give us the numbers you got during both tests.

 

[solarboy]

Is that the recommended salt level for your machine? Some machines need 4500 or more ppm.

 

[Guest]

If you crack the unions at the cell while its running and fill up your test vial, you should have lots of FC. If not, your cell is the problem. If that's ok, then you have something organic that is taking your FC. 84 F is really where algae starts to get comfortable. I would just start shocking for the next couple days. I had the same problem and that worked for me. Since my Aquarite, I have had one other SWG and decided it wasn't worth it... Set it and forget it really doesn't exist!

 

[swbill]

I had added 2 1/2 gals chlorine around noon yesterday. At 7pm last evening, I did the DPD chlorine test. FC and TC were 0 again. I added another 2 1/2 gals of chlorine around 7:30pm and then did the FAS-DPD test at 9pm using the 25ml mark. It took 89 drops of 0871 to turn clear. I added 5 drops reagent #3, solution turned very slightly pink. It took only 3 drops of 0871 for the solution to go clear. This morning at 7:30am it took 91 drops 0871 for solution to turn clear and same result with CC.
So I had 17.8 ppm of FC last night and 18.8 ppm FC this morning and .6 ppm CC (pump runs midnight - 6am as well as 9am - 9pm).

Regarding salt level, the manual on the cell has a range of 2600 - 3200.

I have tried cracking the union on the output of the cell after it has been running a couple of hours. It tested maybe 1.5 ppm. I had called Goldline support, they were not much help. Tech kept saying "I can tell you, you have a phosphate problem even if it measures 100". Can anyone tell me what the chlorine output should be right at the cell?

 

[Bama Rambler]

With a CC of .6 you need to keep shocking.

We normally quote the 10ml test criteria for passing the OCLT (overnight chlorine loss test) but if your using the 25ml test your cc's need to be .2 or less to pass it. It looks like you didn't give the chlorine quite enough time to circulate good throughout the pool before the evening test because there's no way the FC could be higher in the morning than in the evening unless you were running the SWCG, which invalidates the test anyway.

You should also be running your pump 24 hours a day while shocking.

There's no use fighting the SWCG issue until you're absolutely sure you have nothing organic consuming the FC. Once you pass the OCLT with the SWCG off the entire time we'll get back on figuring out if you have a problem with the SWCG or not and go from there.