SWG FC levels

Jump to latest Follow Reply
S

sbcpool

Well-known member
Mar 10, 2015
728
Upland, CA
How are the TFP FC recommendations for pools with an SWG calculated? Specifically, what are the assumptions behind it?

For example, if you punch in CYA of 50 it will recommend a target FC of 3. If I followed that recommendation my FC would fall below the minimum every day. It seems like perhaps those levels are based on the assumption that the pump (and SWG) will be running all or most of the time.

My pump will only be running at night for as long as is necessary to generate enough FC that at the start of the next pump run the FC will still be above the minimum. I'm thinking those SWG recommendations will not apply to me.
 
The target is 3. Never to go below that. You test at the time your FC will be at the lowest point. Typically right before the SWCG starts for the day. If you run overnight, the FC at the end of your run will be 3 ppm plus your daily loss.

The SWCG target value is best followed by running the SWCG for long run times, primarily during sunlight. In your case, you should target the liquid chlorine value for a more conservative operation.
 
  • Like
Reactions: Newdude
sbc,

You have an IntelliFlo pump, so I would not think it would cost much to run it 24/7. It does not appear that you have a heater, so you could run at about 1200 RPM most of the time. I'm sure our electrical rates are not the same, but I can run 24/7, mostly at 1200 RPM for less than $20 bucks a month.

Are you running faster that 1200? If so, why?

I would also think about bumping your CYA up to 70 so that you will have less FC loss per day.

Thanks,

Jim R.
 
The value that Poolmath prefills is 7.5% of the CYA, which gives you some buffer to the minimum of 5% of the CYA. These values (the percentages that is) work for the majority of SWG owners when following the recommended values for CYA, and that's where your troubles start, trying to maintain a SWG pool with CYA 50.

Looking into the FC/CYA Levels, you'll notice that the SWG-table only starts with 60, with the footnote that 60 is not recommended, recommended is to be around 80. That's where CYA provides excellent FC protection, making 7.5% a reasonable target.

When below recommended CYA levels, PoolMath still extrapolates the FC recommendation, but with 7.5% it will indeed be difficult to ensure staying above 5% minimum, and you should choose a higher value within the recommended target FC (for that non-recommended CYA level). When going to the CYA tab in PoolMath, it will notify you when outside the recommended range.

No harm to generally stay at the higher end of the target range. If in doubt, choose higher.

Remember, any FC up to SLAM for your CYA is safe to swim in (but you would have unnecessary FC losses to UV when doing so permanently, and not being able to check pH makes that also a bit impractical).
 
  • Like
Reactions: Mdragger88
mgtfp said:
The value that Poolmath prefills is 7.5% of the CYA, which gives you some buffer to the minimum of 5% of the CYA. These values (the percentages that is) work for the majority of SWG owners when following the recommended values for CYA, and that's where your troubles start, trying to maintain a SWG pool with CYA 50.
Click to expand...
I'm not trying to run a SWG with CYA 50, I'm trying to illustrate what's going to happen to FC consumption vs production. Since I don't know my pool's FC consumption at 70 CYA I chose to use the example where I do know.

I would run CYA at 100 if it proved to be economical for chlorine usage, except for the fear that one day I may need to do a SLAM with mustard algae shock (I've had to do it several time before). The expense of even partially draining the pool or the chlorine needed to do that at high CYA scares the bejeezus out of me ($58 of chlorine just to reach mustard algae shock).
 
Jimrahbe said:
sbc,

You have an IntelliFlo pump, so I would not think it would cost much to run it 24/7. It does not appear that you have a heater, so you could run at about 1200 RPM most of the time. I'm sure our electrical rates are not the same, but I can run 24/7, mostly at 1200 RPM for less than $20 bucks a month.

Are you running faster that 1200? If so, why?

I would also think about bumping your CYA up to 70 so that you will have less FC loss per day.
Click to expand...
It would be a little over $30 a month for me to run at 1200 RPM. With my plumbing 1200 RPM is just teetering on 20 GPM with a freshly-cleaned filter. I think I'd probably have to run a little higher than that to keep the flow switch activated even when the filter gets dirty. Mine's a VSF, so I can set it for a constant flow rate and it will dynamically adjust the speed as needed. Convenient in this case.

However, it is true that I can run the Intelliflo much longer than my old single-speed pump far more economically. Even if I don't run it 24 hours I might run it for 12 or so, which should allow the IC60 to theoretically produce 1 lb of chlorine. That should far exceed what's needed in my pool even if it's not running during the day.

If I can get it installed I will probably experiment with running it during the day just at just the right setting to generate FC at the same rate that it's being consumed. In theory that should allow me to actually run it a little bit less than if I had to "charge up" the pool with enough FC overnight to last until the next night without going below the minimum.
 
I should probably start a new thread for this, but it's related to this topic too.

Since the Intellichlor has an integrated flow switch there doesn't seem to be any trick available to keep it from generating when the pump is in "SPA" mode. I really want to avoid manually turning it off while the SPA is in use because it's 100% guaranteed that the wife and kids will forget to turn it back on and I won't know until the pool turns green.

How do you Intellichlor users handle that?

Something like the opposite of the 24-hour boost button would be good.
 

Enjoying this content?

Support TFP with a donation.

Give Support
SCE is a criminal enterprise IMHO. They have so much shady stuff. For example, they have a scheme called their "baseline credit." You get a rebate of $0.09 per kWh on your bill up to your baseline. They apply that to all metered electricity, even negative. That means if you have grid-tied wind or solar you pay SCE $0.09 for every kWh you give them to sell to your neighbors at $0.65. That's not enough, though. They're pushing for a solar tax in California of $8 per month per kW of installed capacity.

If you had an 8kW system and used 10% less than it produced one month, you'd end up having to pay SCE a total of $75.97 for having the audacity not to use any of their electricity, but also for giving them 132kWh for free from your system.
 
Last edited:
  • Wow
  • Like
Reactions: Pins, Mdragger88 and bertschb
I retired from SCE’s IT department in 2015. I moved to Las Vegas at the end of 2019. I had a pool in Orange County, and ran our a/c when it got too hot not to. However, as an employee and then a retiree in the service area, I got a 25% discount. My bill probably averaged $75 - $85 a month over the whole year. It helped that I got a vsp along with the rebate when I had the pump installed replacing the single speed I once had.

Now if you want to discuss how much I/we pay for electricity here in Las Vegas, running the a/c 24 hours a day, that is another thread.
 
sbcpool said:
I'm not trying to run a SWG with CYA 50, I'm trying to illustrate what's going to happen to FC consumption vs production. Since I don't know my pool's FC consumption at 70 CYA I chose to use the example where I do know.
Click to expand...

Sorry, misunderstood your first post there. Just wanted to point out that the recommended FC at CYA 50 is not really a recommendation, but has to be seen more like an extrapolation into the non-recommended CYA range.

I personally am following more the non-SWG levels in my SWG pool. Just seems more stress free for me. I always have enough buffer to accommodate a spontaneous gathering of my son's friends without having to worry about topping up with liquid chlorine. FC will go a bit lower, but still well above min, and because it's a bit lower the next day, I will lose less to UV and my SWG will catch up within a day usually.

I rather pay a bit upfront for an oversized SWG than having to worry about not being able to run my FC a bit hot.

But I think you are right, the "explicit" SWG-target value probably works best when running the SWG 24/7 in a way where you ensure that you sit at target at sunset. Then you will overproduce some over night and start the next day a bit hot.
 
Last edited:
  • Like
  • Love
Reactions: PoolStored, SoDel and Mdragger88
With the IC60 I should be able to to keep a SLAM going once I use liquid chlorine to get to that level. If not, it will go a good part of the way toward keeping the level running 24x7 if it truly generates 2.0 lbs per day of actual FC.

My August and September bills are around $400 because of the constant heat and nights that don't go below 80°F, but in the winter it goes as "low" as $130. Keep in mind I have two plug-in hybrid cars, too. That adds about 10 kWh per day (but still FAR cheaper than gas - a kWh gets me about 5 miles, which is equivalent to gasoline at $2.31).
 
sbcpool said:
With the IC60 I should be able to to keep a SLAM going once I use liquid chlorine to get to that level. If not, it will go a good part of the way toward keeping the level running 24x7 if it truly generates 2.0 lbs per day of actual FC.
Click to expand...

Be careful with that. During the SLAM you are blind for pH, and even after adding MA before the SLAM, pH can still be above normal ranges due to raising FC a lot and maintaining the elevated level, especially if the SLAM takes a bit longer, or at Mustard-SLAM-FC. Could end up in a scaling frenzy inside the cell.

Have a look at the example calculations in this post:

Use MA to neutralize pH effects of bleach?

When you guys add bleach, do you also add some muriatic acid to neutralize the pH effects? From other sites i've read, 1 gal of sodium hypo is pH neutralized with 5 fl.oz. of MA. If i'm gonna shock and initially bring the pH down to about 7.2 for higher sanitation strength, adding several...
www.troublefreepool.com www.troublefreepool.com
 

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