Chlorine level, SWG and pump run times

Jump to latest Follow Reply
I

istreich

0
LifeTime Supporter
Jan 19, 2014
37
I have been struggling to keep my FAC level in range. As you can see in signature, we have a SWG pool with a cover and live in GA.

First, my readings:
FC 0-0.5
Salt: 3100
TA 120 (recently reduced from 160 to 125 to 120)
CH 325
CYA 90
pH: 7.2 (down from 7.6 as I just added acid to reduce TA...)
TEMP 85
Water Quality - Clear
using a TF100 kit

A few issues:
- I am really struggling to get my TA lower than 120. It has been as high as 160 but usually around 120. Keep on adding muriatic acid (once pH is back up and 45oz max at a time) but not much success. Will continue doing so.
- I have had to supplement my SWG with some chlorine powder the past few weeks as my chlorine is "crashing". I have run various options on my pump and SWG but nothing conclusive so far. Ditto on SWG %, from 20% to 60%
- My pool guy has suggested 20 hours at 1000rpm and 4 hours at 2800rpm (high speed). At 1000rpm, SWG is turned off.
I have also tried 1750rpm for 24 hours. Based on some estimates, GPM equivalent are around 25GPM for 1000rpm, 43GPM for 1750rpm and 70GPM for 2800rpm.
I am really trying to find the optimal schedule to maintain roughly 1ppm of FAC, keeping the water clear (sometimes gets a little cloudy and "greasy" at the surface) while minimizing pump running time. Pool is covered most of the time except for swimming... obviously ;)

Any suggestion to reduce my TA level closer to a 70-80 target? I will continue to pour 45oz of muriatic acid at the time after aerating pool to get pH back to proper range. Other suggestions to help welcome.
More importantly, any suggestion on pump schedule. How much time should I "run" the SWG and at what %. At 1000rpm, it runs through filter but no salt generated.
- shall I increase to 1200rpm (or some other number to just start SWG) and run for 20 hours then 4 hours at higher speed?
- shall I leave to 1000rpm but less time and more time at higher speed and maybe higher %
- other method?

I have been scratching my head to find a solution to maintain my FAC at a proper level without adding powder chlorine.

My filter was cleaned recently and SWG inspected. nothing to report...

Thanks a lot in advance.
 
Welcome to TFP! Good to have you here :)

To lower TA more quickly, try dropping pH to 7.0 instead of 7.2 or just leave it for now while you get the FC sorted, which is more important.

Stop using powdered chlorine because each time you add it, you're also adding CYA. Use pool chlorinating liquid or plain (not scented or splashless) bleach. Use only products that show a % sodium hypochlorite on the bottle, and then just buy whatever gives the best deal on sodium hypochlorite, your best source of FC for your pool.

Use a minimum pump RPM that allows the SWG to run consistently. Note that as the filter gets dirty the flow will be reduced, so if 1200 works, try 1300-1400 to allow for the reduced flow.

Your IC40 will need to run for 10 hours per day at 100% to provide 2.5 ppm per day (season-long average for a clean pool). On hot days with bather load, it could need 4 ppm per day, or covered without use it could be much lower. When it's beyond that range, it means there's organic contamination.

As far as pump run time and if it were me, I'd need to be convinced that the high speed run is needed, but there could be other reasons for that. Here's an article on pump run time that may be helpful: Pool School - Determine Pump Run Time

At 90 CYA, minimum FC is 5 ppm, target is 8 ppm. Your plan to use 1 ppm FC will not keep your pool safe or free of algae. Use this chart to determine safe FC levels: Pool School - Chlorine / CYA Chart

I recommend you raise FC to 8 ppm to make the pool safe, and then do an overnight chlorine loss test (OCLT) to see if algae is causing your chlorine loss. Pool School - Perform the Overnight FC Loss Test (OCLT)

At 90 CYA, you should also do a diluted test to re-assure yourself that CYA is not higher. See point #9 in this article: Pool School - CYA

Excellent post by the way. You've included great information. Thanks! Feel free to ask any question or make any comment that comes to mind.
 
Thank you very much for those clear indications. This is extremely helpful.
I have been working on them in the last couple of days and made a few changes...
The piece of good news is that my CYA is closer to 60 than 90. Probably around 65... I will try to keep it there, maybe slightly higher as per the links below.
However, I am still working on raising my TA. Each 48oz of muriatic acid (apparently the max at a time) reduces it by approx. 5ppm. I think I am down to 105 and have quite a bit still to go.
Could I try to dump more acid in one go? Like double that? My pH seems to hold around 7.2. I guess there is a risk the pH could drop big time but asking...
Otherwise, in 4-5 days, I should be there...

I have switched to 8.25% bleach and I will monitor how it does, combined with my SWG. Still working on this to nail the right duration/speed/%...
Based on your calculation below, is there a difference between running 10 hours at 100% vs. 20 hours at 50%? Is one better than there other for the SWG? Pump? Water clarity? Obviously operating cost is quite clear... :)
I will perform an OCLT - I was waiting for my FC level to be back up. I will check tonight - if not tomorrow.

Thanks again and all additional advice welcome! So great to have you and your amazing knowledge/support!!!


needsajet said:
Welcome to TFP! Good to have you here :)

To lower TA more quickly, try dropping pH to 7.0 instead of 7.2 or just leave it for now while you get the FC sorted, which is more important.

Stop using powdered chlorine because each time you add it, you're also adding CYA. Use pool chlorinating liquid or plain (not scented or splashless) bleach. Use only products that show a % sodium hypochlorite on the bottle, and then just buy whatever gives the best deal on sodium hypochlorite, your best source of FC for your pool.

Use a minimum pump RPM that allows the SWG to run consistently. Note that as the filter gets dirty the flow will be reduced, so if 1200 works, try 1300-1400 to allow for the reduced flow.

Your IC40 will need to run for 10 hours per day at 100% to provide 2.5 ppm per day (season-long average for a clean pool). On hot days with bather load, it could need 4 ppm per day, or covered without use it could be much lower. When it's beyond that range, it means there's organic contamination.

As far as pump run time and if it were me, I'd need to be convinced that the high speed run is needed, but there could be other reasons for that. Here's an article on pump run time that may be helpful: Pool School - Determine Pump Run Time

At 90 CYA, minimum FC is 5 ppm, target is 8 ppm. Your plan to use 1 ppm FC will not keep your pool safe or free of algae. Use this chart to determine safe FC levels: Pool School - Chlorine / CYA Chart

I recommend you raise FC to 8 ppm to make the pool safe, and then do an overnight chlorine loss test (OCLT) to see if algae is causing your chlorine loss. Pool School - Perform the Overnight FC Loss Test (OCLT)

At 90 CYA, you should also do a diluted test to re-assure yourself that CYA is not higher. See point #9 in this article: Pool School - CYA

Excellent post by the way. You've included great information. Thanks! Feel free to ask any question or make any comment that comes to mind.
Click to expand...
 
If you are running your VS pump at a low speed for longer periods then it will improve water clarity because the filter will be more efficient at lower flow. I run my pump at 1100 rpm for skimming, filtering, making chlorine with the SWG and solar standby. It uses 150 watts at 1100 rpm. I prefer to run my pump for 12 to 24 hours per day depending on solar needs and tree activity. We have lots of trees and when they are busy we need lots of skimming to keep debris off the pool floor. I also like to have the SWG adding FC all day.
 
Great post from pooldv, as usual.

You can run any SWG % you want, makes no difference to the SWG%. It's purely about getting the appearance and cleanliness you want for the least money. Skim lots if you need to, and turn the SWG % down, or vice versa. 10 hours at 100% or 20 hours at 50% both use up 10 hours of cell life.

You might be raising CYA before you know it, to lower SWG % or run time, but if you need to SLAM, that's great news!!

Totally normal to be doing some liquid FC top-up as you dial it in. So have you done an OCLT?
 
Thanks to both for feedback.
Not yet for OCLT but trying tonight. Did test at 1.15am and will try to test again at 8am. Will it be enough time to see?
By the way pool has full cover on.

On TA, any view on accelerating process and going beyond 45oz of muriatic acid or better/safer to be patient...?

I will "play" between 10 and 20 hours and see optimal. Despite cover, it was sometimes s little fuzzy... Once TA and FC are correct it will be easier to evaluate.
 
I'll leave the quantity to you per PoolMath, and mention that taking pH to 7.0 (instead of 7.2) will speed up the TA lowering process. It will make your water aggressive (as does pH 7.2) but it's only for a short time, so plaster etching would be immeasurably small.
 
One thing you might not be aware of is that your SWG will keep your chlorine level maintained very well, but it is not very good at raising the chlorine level. Use some bleach to get the chlorine level up to your target and then work on keeping it there by dialing in your run times.

Also, I wouldn't be as concerned with the TA until you get the chlorine up to the correct level.
 
Short night :)
Anyway, did an OCLT and results:
1.15am FC 3 CC 0-0.5
8.45am (7 hours) FC 2.5 CC 0-0.5
Looks like chlorine loss is about 0.5. Maybe a tad less. Pool was covered all time and temp has been pretty cool... For Atlanta I mean :)
Swg off all time last chemical (acid) 4 hours earlier.
Let me know what you think.
Thanks again.
By the way, what is safe time to swim again in pool after adding muriatic acid?

- - - Updated - - -

Thanks Griswald. I have learnt that experimenting... Bleach has become my new best friend :)

Griswald said:
One thing you might not be aware of is that your SWG will keep your chlorine level maintained very well, but it is not very good at raising the chlorine level. Use some bleach to get the chlorine level up to your target and then work on keeping it there by dialing in your run times.

Also, I wouldn't be as concerned with the TA until you get the chlorine up to the correct level.
Click to expand...
 
You can swim as soon as the MA is mixed in. 30 minutes is a good guideline to give the pump some time to mix the water.

The safe pH range is between 7.2 and 7.8.

- - - Updated - - -

FC needs to be raised to keep it between bare minimum and target for your CYA level
 

Enjoying this content?

Support TFP with a donation.

Give Support
Chlorine level crashing - not sure SLAM working...

I am back with new FAC problem! I can't manage to keep my FAC to a decent level... I have been adding a lot of chlorine (more below) in various forms (8.25% bleach and/or 73.25% powder) and it goes back to zero in a matter of hours of days.
Water is crystal clear and I have tested for bacteria with a kit giving me negative results. Stopped by at Leslie's and they have found traces of phosphates... We shall see...
Anyway, I have been following the SLAM protocol but I am not sure I am making progress...

Earlier today, I dropped 8 packs of 73.25% to reach a FC of 24 (goal for a CYA of 60) from 0/0.5. Three hours later, I was down to 21. Added more bags and some bleach to get back to 24. Two hours later, I am back down to 15. Just added 400oz of 8.25% bleach and will test in the morning.
Before SLAMming, I had already added over 800oz of bleach and 4 lbs of 73.25%.
I guess I will continue the SLAM process but I am not sure what is going on and what I am looking for.
Details in my signature but SWG pool with a cover and live in GA.

For the recent numbers:
FC 0-0.5 before SLAM. No CC.
Salt: 2700 but SWG off because of low temperature
TA 105
CH 325
CYA 60
pH: 7.4
TEMP 60
Water Quality - Crystal Clear
using a TF100 kit

Thanks a lot in advance for your precious help! Running out of ideas and not sure if I and how long I should keep on adding chlorine...
Water crystal clear, other chemical levels fine (I think) but chlorine being eaten like crazy...
 
I went earlier today and same reading.
I thought too it could be test but unfortunately it is not.
It is showing chlorine after I pour bleach and/or powder. The chlorine is just being consumed very fast despite clear pool, and pretty much balanced chemicals.
 
Good to see you again. I strongly recommend you stop using any powdered chlorine and stick to 8.25% bleach or 12.5% chlorinating liquid. What is the manufacture date on the chlorine (five digit number).

Is it calcium hypochlorite that you used? How many ounces per pack?

So if the water is perfectly clear, what made you decide to SLAM? How long was the pool at 0-0.5 FC?
 
Thanks again for your help needsajet.
I will check date on bleach but 3 different stores and recent purchase (days).
Yes, calcium hypochlorite at 73.25%.
Decided to SLAM as chlorine keeps on disappearing. A couple of weeks ago, I added bleach to get to 2-4 ppm but it was down to zero next day. Decided to shock the pool to clear any potential contaminant. To my surprise, chlorine went down a day or two later to 0. Tested by both myself and store.
Based on that decided to SLAM it yesterday. I thought that after a couple of rounds, FC would start stabilizing... so far has not...
I have not checked this morning yet (roughly 10-12 hours after last chlorine pour - bleach) and will report measurement shortly.
Running out of ideas especially as water crystal clear and no trace of bacteria (at least based on test).
But clearly not passing OCLT as I seem to lose between 1 and 4 ppm FC per hour...
It will be interesting to see how much I have left this morning.
 
I'm not sure how to say this, but it seems like time to commit to the SLAM process, to the letter. That means a start day where you maintain FC at SLAM shock level by adding chlorine four, five, six times if need be on the first day, then 3 to 4 times on the following days. "Maintain" is really important for the SLAM to work. I have to suggest strongly to follow the procedure and not test or adjust anything but what's in the SLAM procedure. Regular brushing and thinking about places where algae might be hiding are also important. Good luck with the process. It'll work!

The OCLT is a specific procedure and is only done overnight, when there is no sunlight.

Please add your pool information to a signature and add your location to your profile. Those things really help you get the best possible help. There's a link in my signature (Read before posting) that has the instructions and tips for getting the most from TFP.
 
Thanks. I agree. Just checked this morning and down to 3.5 FC. Whatever it is, it is eating chlorine like crazy.
I may have to restart the process during the weekend. I thought yesterday would be enough (kept FC At 24 or above all day with 3 or 4 additions) but obviously not.
By the way any risk to the pool/plaster to dump so much chlorine? Unfortunately my CYA is at 60 so need quite a bit.
Filling my bin with gallons of bleach :)

Sorry for signature. It looks like when you reply on mobile, it drops signature. Hopefully it will appear on this one.

Thanks again and fingers crossed!
 
This is a classic case of a SWG pool with nascent algae. The water might look good to you but it is not, the OCLT tells the truth.

You need to follow the SLAM procedure to a tee. The FC needs to stay at or slightly above the minimum SLAM level at all times. Every time the FC drops below the SLAM level the algae makes a strong revival and you are not gaining ground on killing the algae.

Stick with liquid only and I suggest turning on the SWG to 100% to help for now. Some might say to turn off the SWG, but I find it to be of value to help maintain the FC when it is dropping in your situation.

What is the water temperature?
 
+1 to ping's comments. The SWG can be very helpful in your situation.

The chlorine levels recommended as part of TFPC, including shock levels, will not harm anything when added to the pool water.

Spills or drips of concentrate outside the pool should be rinsed off, and many here have dedicated pool clothes that already have a few spots!
 
Thanks guys. I tested again the pool tonight and my FC is down by 3 to 0.5 since this morning (about 12 hours with SWG off and no chlorine added) with low air temperature (50F) and cover closed. By the way, water temperature is 65 thanks to heat pump. I will definitively SLAM it this week-end as it looks like I need to be there the whole time.
At 60 CYA, pool calculator says I need approx. 8.25 gallons of 8.25% bleach. And based on the Chlorine consumption of about 3-4ppm per hour (See above), it looks like I need to add at least one gallon per hour (all theoretical I agree) to stay at shock level. This tells me I will need at least 20 gallons for the first 12 hours and maybe as much the next day! Possibly between 30 and 50 gallons. I need to buy a truck!!! :)
A few questions:
- can I use calcium hypochlorite at 73.25% powder? Not saving money but at least saving space and my back! :) I know it is not ideal and the site always recommends liquid chlorine above powder. But not sure of the drawback of this one as pure chlorine and not CYA impact. Only thing I could find is possibly a thin film on the pool bottom but not sure...
- at Target and Home Depot stores, I can only find 8.25% bleach. Where can I find 12.5% liquid chlorine? Same idea - save plastic and trips! I live in Atlanta, GA (USA)
- I think I know the answer but any benefit to use algae control solutions?
I am committed to the SLAM process and you guys are incredibly helpful. I am just trying to make sure I explore all paths before buying all Home Depot stock of bleach :)
I will see how much chlorine I can generate from the SWG (turned off right now) assuming that water temp is high enough for it.
I know an option is to drain water and replace with fresh water but I would prefer to avoid this and not precious water as we are still in drought condition right now and I hate wasting water.

Thanks a lot for your great help!!!
 

Enjoying this content?

Support TFP with a donation.

Give Support
You must log in or register to reply here.
Thread Status
Hello , This thread has been inactive for over 60 days. New postings here are unlikely to be seen or responded to by other members. For better visibility, consider Starting A New Thread.
Top Bottom
Back
Jump to latest Follow Reply