Cannot maintain FC with SWG

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swbill, did you have the cell off when you did the FC test? Doing the FC test at shock level is difficult due to the accuracy required by the test. Also, by my calculation you lost 13ppm FC the day before from noon to 7pm which shows you have organics. You should run the test with the SWG off and the FC level around 3 - 8 ppm from sunset to sunrise.

When did you run the SWG test, before or after you shocked? What you are looking for is the difference between the pool FC level and the output of the SWG. So if the pool FC is 5ppm and the output of the SWG is 7 then you know you are getting 2ppm out of the SWG. Is this what you did?
 
I think I need to step back. My error, I ran the SWG as usual last night so I need to redo the overnight test. But I want to be clear on what I need to do.
1. Since I lost 13ppm during the day yesterday (with the SWG running), should I continue to shock or monitor the FC until it gets down to 3 - 8 ppm and maintain that until sundown and redo the test.
2. While shocking, should the SWG be turned off?

To answer Carlos, I tested the cell output last weekend before I found this forum. The reason I am asking about the output at the cell is I have not been able to get a straight answer from the pool stores I had gone to or from Goldline support. Goldline told me one way to test the cell is to put an old cell in, take the new one, immerse it in a bucket of pool water and plug it in to the control panel then turn the system on and I should smell chlorine coming out of the new cell.
 
It's a good idea to step back and regroup.

Here's what you need to do.
  1. Turn the SWCG off.[/*:m:aisyzhoa]
  2. Keep the pool at shock level, testing and adding as often as every hour if possible.[/*:m:aisyzhoa]
  3. Test the FC & CC tonight after the sun has gone down and at least an hour after the last chlorine addition and record your results.[/*:m:aisyzhoa]
  4. Do not add any more chlorine to the pool after the last FC/CC test.[/*:m:aisyzhoa]
  5. Go to bed![/*:m:aisyzhoa]
  6. Wake before the sun is on the pool and test the FC & CC again and record your results.[/*:m:aisyzhoa]
  7. Come back here and post your evening and morning results.[/*:m:aisyzhoa]

That should be a pretty good step by step account of what you should do at this point.
 
Reran FAS-DPD last night, again using 25ml. Here are the results;
8pm reading last night;
FC 17ppm (85 drops 0871)
CC .2 (1 drop #3)
8am reading this morning;
FC 13.8 (69 drops 0871)
CC .2 (1 drop #3)

Nothing has been added but chlorine, SWG has been off.
 
With that much of an overnight loss, you need to shock the pool. Refer to the CYA chart for your shock level. Using the 10 ml sample is fine and will save reagent. Shock with liquid chlorine until the FC holds overnight and the CC is .5 or less.
Once it holds, your SWG should be able to keep up....yours is a classically described "nascent" algae situation - it's not clear why it happens quicker in some pools than in others.
 
Poolsean, the pool was resurfaced this past June/July with Pebble sheen. Per pebble tec, we could not use salt water for the first 30 days while the surface "cured". Surfacing was completed the end of June, pool was fresh filled using only chlorine (I checked the chemicals every day, brushed pool every day for first week). There were no balance problems other than PH was always going up, chlorine levels were holding (I used a floating chlorinator). After the 30 days, we turned on the SWG, removed the chlorinator and installed a new filter cartridge. About 2 days later, the chlorine level dropped and my saga began.
 
The information from PebbleTec about waiting on the salt is correct (I actually prefer 60 days before adding salt) as plaster takes 28 days to cure out. They gave you accurate advice, and it is not what is affecting the CH levels. As for the pH, Pebble pools tend to require more acid (nobody seems to know why, although one thought is that they have more aeration than plaster pools due to the product being installed on more high end pools with more water features); do you have a raised spa/waterfall/etc.?

Have you measured the output as soon after the cell as possible? If you can get a sample of the water after is has passed through the cell (try cracking a union and collecting the water) you can check output.

From your overnight drop it is obvious something is eating your FC, and your SWCG is not going to be able to maintain shock levels. You really need to kill whatever it is you have consuming chlorine and then make sure that your SWCG is producing to maintain your pool. As long as the cell is producing, and once you have killed the culprit through the shock process, you should be in business!
 
After shocking for 2 days, I re-ran the FAS-DPD test last night;
8pm
FC 21.5
CC .2
7am this morning
FC 20
CC 0
I am going to shock again this afternoon and then run the test again.
Thanks to all, I appreciate any info provided.
 

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Well I was not able to rerun the FAS-DPD test last week, I ran out of the 0870 reagent.... But there apparently is good news (and a question of course). Since the last shocking on 9/14, I have maintained a FC of almost 8 running the SWG on 85% with a CC of 0. That is 5 days without adding chlorine...has never happened before. Now to the question, since the last shocking, there was a white substance that had come out of the return jets, sort of very tiny flakes. I vacuumed it up and it has not appeared in the past day or so. Could this be the residue of whatever organic was in the water?
I have ordered FAS-DPD replacment reagents (no one local had it), should be in tomorrow. Will redo the overnight test at that point.
 
Most likely it is the calcium from the cell reversing polarity. Be careful if it is going into your spa (if you have one) as well, as there is no pool cleaner in a spa to pick it up like in a pool! It will build up on your steps and benches if left to sit.
 
Since the last FAS-DPD test on 9/27 (less than 1ppm FC loss and zero CC), the FC has gone down hill again. Today, it is maybe .5ppm and the pool is clouding up. I am ready to rip this SWG off the wall and toss it in my lake. But, being stubborn, I will get this fixed, so I am going back to square one. I added 2 1/2 gals of chlorine this afternoon and once the pool clears, I will beging testing again.
Right now, these are my readings (all taken with Taylor test kits);
FC < .5
CC 0
PH 7.4
TA 150
CH 300
CYA 50
Salt 3200
Water temp 84
I did take a water sample directly from a return jet, it was 3 ppm with the Aquacell T15 running at 90%.
 
hmmm if it's clouding up you may have an algea problem & need to shock

What else happened since then? not long ago you "maintained a FC of almost 8 running the SWG on 85% with a CC of 0. That is 5 days without adding chlorine.."

Wondering what threw it wonky again. Cell clean? TA looks a high for a SWG pool but that should not affect FC...

FYI i am a relatively new pool owner, SW system is undersized & i've delat with a few challenges as well.... hang in there!
 
Just wanted to take the time to thank everyone who helped me with this problem. After shocking my pool for 4 days (like I should have the first time), my SWG is now maintaining a FC level as it should. Also, during this time I was fighting a high TA and again, your suggestions on using aeration to lower it worked like a charm.
Lessons learned;
1. Listen to those who know what they are talking about (the forum)
2. Most pool stores do NOT know how to test your water, get your own Taylor test kits....they are worth every penny.
3. This is chemistry, not magic. Balance can be attained by following the correct steps.
4. Share the knowledge when asked.
Once again, thanks to all who helped me. Bill.
 

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