SWCG performance

[danman]

Update:

I have my CH raised, and I raised my FC to about 8( it was 8 on Monday ) to knock out any algae, and I did have a little along the edges of steps and close to the surface on a couple sides.

water temp(according to Jandy PDA): 92 **note: I forgot to update my temp on my earlier post.
FC: 6.5
PH: 7.6
TA: 70
CH:290
CYA: 80
Salt: 3000
CSI: -0.08/-0.21

So I feel I need to get my CH a bit higher, since TFP recommends between 250 - 350.

I'm still a bit amazed at how quickly my PH rises. At least I feel it rises very fast. I have been measuring out the ounces of MA I put in and will keep a close eye on that until I feel I understand how/why it's doing what it's doing.

Couple thing I'm concerned about is my salt cell.
1. Granted it's the first I have ever owned, but I don't know if it can maintain a FC level that is noted up here(5,6, and even higher). It seems like I have to run it all the time to keep it at around 3 - 3.5
2. Every time the cell reverses my Board says "Service" and General fault 123. Which listed below. I will inspect/clean the cell this weekend. But I find it odd that it does that every time.

Extremely Low current to Cell.
1. Clean or replace cell if necessary (see Section 6.3).
2. Check DC Cord.

 

[danman]

I checked my FC today, and it was at 6.5 yesterday afternoon. I just checked it again and it's down to 3.5. I'm beginning to convince myself my cell has issues. It is running at 100% for 12hrs a day.

 

[jblizzle]

At 100% for 24 hours, the PLC1400 can optimally produce 1.25 pounds of chlorine gas.
In your 18k pool, that is 8.3 ppm of FC.

You are running 12 hours, so at best it is adding 4.15 ppm of FC ... this is right on the upper normal daily FC loss (2-4ppm).

I did not look back ... have you run an Overnight Chlorine Loss Test to confirm there is nothing in your water?

 

[danman]

Let me read up on that and I'll post back with results.

 

[danman]

So maybe I'm off base here, but I'd like to know the formula you use to figure this out "optimally produce 1.25 pounds of chlorine gas.
In your 18k pool, that is 8.3 ppm of FC"

I ask because I run my pump from 8am - 8pm, between 6pm - 6:30pm the sun is no longer on my pool, and the sun is on it from probably 10am till 6pm. So I went out to test right before the sun went down and my FC was back up to 5! it was 3.5 around 6ish, but at 8pm it had already moved back up to 5ppm. Does the sun eat the chlorine up that quick? Or could I have taken a bad reading earlier??

 

[jblizzle]

I used PoolMath and put in 20 oz of chlorine gas toward the bottom in the effects of adding pool chemicals area, making sure the pool volume at the top was set to 18000 gallons.

The sun can use it up pretty quickly. Although not as fast with the higher cya levels. Perhaps one of your tests was a little off. I would still suggest doing the oclt.

 

[danman]

interesting.. I'll post my OCLT result in the morning.

 

[danman]

my OCLT test result shows my FC fell from 5.0 to 4.5 over night. so I was wrong it sounds like the cell is working exactly as it should. I want to get my CH just a bit higher, and then I think I'll be good. One last question on this thread. Instead of running my SWG from 8 - 8, should I run it 9 - 9? If I run it till 9, it will have about 2.5 hours or so of time without heavy direct sun. My thinking is maybe that will help keep my FC a bit higher.

 

[mknauss]

I find it best to run the SWCG during the time that chlorine has the highest demand due to UV or bather load/organics. So adjust accordingly.

The height of summer is just about behind us, and you will start to see less FC demand from UV. At that point you can reduce your pump time or your SWCG on time.

Take care.

 

[danman]

This has been an excellent thread. Thank you all.

 

[Philo]

"my OCLT test result shows my FC fell from 5.0 to 4.5 over night. so I was wrong it sounds like the cell is working exactly as it should"

That's not the conclusion. The OCLT will tell you if you have algae growing.

 

[danman]

the pool school article says "If your FC level remained the same, or went down by 1.0 or less, the water is clean. There isn't any living algae or other organic contamination in the pool." so I know the water is clean. I think my salt cell is performing fine, but I'm pretty cautious, so I will probably check it again tonight.

 

[Philo]

If you want to check the SWG performance:

**Test for FC at Sunset

**Run the SWG over night at 100%

**Test for FC first thing in the morning.

There should be a nice bump in FC.

P.S. you can pass the OCLT and still have a bad SWG (but not for long).

 

[Jimrahbe]

dan,

You did have your cell OFF when doing the OCLT right??? If so, and you did not lose anything overnight, you can run the OCLT with the cell ON and your FC should go up by the amount of chlorine that your cell produced...

Jim R.

 

[ping]

Another thing that could possibly be the issue, is the cell is worn out on one side and when the cell switches polarity it either works or stops making chlorine. This was the exact thing that was happening with my cell for the last few weeks. I just got it replaced and everything is back to normal.

 

[danman]

I agree, I can do that test.

- - - Updated - - -

dan,

You did have your cell OFF when doing the OCLT right??? If so, and you did not lose anything overnight, you can run the OCLT with the cell ON and your FC should go up by the amount of chlorine that your cell produced...

Jim R.

Yes I did have it off.

- - - Updated - - -

Another thing that could possibly be the issue, is the cell is worn out on one side and when the cell switches polarity it either works or stops making chlorine. This was the exact thing that was happening with my cell for the last few weeks. I just got it replaced and everything is back to normal.

That is interesting. I wonder if that is the deal with mine when it reverses.

 

[danman]

UPDATE:

So I did the overnight test with the Salt Cell running all night. My FC was around 4.0 right when the sun went down, and when I checked it in the morning it was up around maybe 4.5 - 5.0. so a slight bump I guess. I would expect it to be higher. Maybe my cell does have a problem when it's reversing? What do you guys think a standard bump should be if you run the cell all night(chlorine production is set to 100%)?

I will say, my water looks great, I see no algae bloom and running 9am - 9pm, my FC is hanging around 4.0 - 4.5. I've eased up on my MA use, by measuring and paying attention to how many ounces I put in and that has raised my TA back up to the recommended level as well.

 

[mknauss]

Your SWCG produces 1.4# of chlorine each 24 hours at 100%. So you can calculate how much chlorine it produced during the hours you had it on, put that in PoolMath with your pool size, and it will tell you what FC rise you should have seen.

Good luck

 

[kabutotx]

It takes your SWG 8 hrs to produce 3ppm of FC at 100% and working correctly. If you loss .5 FC on your OCLT and only went up 1ppm FC overnight with your SWG I would assume your cell is shot since that would be 1.5ppm FC overnight (Assuming 8 hrs).