FC demand

[rjb1211]

I found the SWG Run Time Calculator. One of the input fields is FC demand.

I know that is a moving target and has too many variables to predict but I need to start someplace. Can someone give me an idea of what to enter as an approximation for this time of year in Pennsylvania while I get it figured out based on my pool?

 

[proavia]

In PA this time of year around 2ppm.
It depends on how much sun you're getting.

 

[rjb1211]

Thank you.

 

[SJPoe]

My pool, with a solar cover, heated, CYA around 70, in mid-Michigan (so not that much different climate-wise to you) is running almost exactly 2ppm right now.

If I set my SWG on 10% @ 24hours (1.5ppm/day), I notice a very slow decline in measured FC.
If I set my SWG on 15% @ 24hours (2.3ppm/day), I notice a very slow increase in measured FC.

Unfortunately, I don't have a 17.5% setting...

 

[Jimrahbe]

rjb,

It does not matter what number you pick because it will be wrong anyway...

I'm with Gene, 2 ppm sounds about right to me..

Keep in mind the whole idea is to try and stay at your Target range or slightly higher.. You never want to try and stay between your minimum and your Target.. Unless of course you just want to get algae...

Thanks,

Jim R.

 

[rjb1211]

Based on your suggestions I started with 2ppm and after monitoring I found that I was dialed in with my IC40 set at 37% which would indicate FC demand of 1.7. My CYA is currently 50 and I have been getting a FC reading at the end of the day of 7. I do intend to bump up the CYA some.

This has been for April with water temps in the mid 60's and daytime air temps mostly from 55 to 75, although the last few days have been much warmer. FC readings haven't changed with the higher temps. It is spring so there have been cloudy and rainy days.

What should I expect as we get into summer weather? Have I got it right that more intense sun is going to increase the FC demand? If so by how much?

BTW - when choosing equipment I was a little concerned that the IC40 wouldn't be up to the task but it appears that was unfounded.

 

[Jimrahbe]

rjb,

An IC40 in a pool in Texas or Arizona, would not work well in the middle of the summer..

Even in PA, your FC demand will increase as we move into the summer..

Kind of the whole point in testing is so you can adjust your FC up or down based on the amount of sun the pool is getting.

In my case, I adjust up about once or twice a month, as we get closer to summer, and then down as we move into winter.

As time goes on, you get a sense as to what is happening and can test less.

Thanks,

Jim R.

 

[rjb1211]

This first year with SWG has a learning curve that I need to learn. During the spring months I found that a 37% setting on my IC40 had good results. The math calculation was that my FC demand was around 1.7 PPM for 24 hours.

Now we are in a heat wave with no rain and bright sun. I am trying to stay ahead of it so I don't start growing algae. It is looking like my 24 hour FC demand is up to around 2.7 PPM.

Does that sound reasonable? I am going to monitor closely - I just don't want this to get away from me while I am fiddling with settings.

 

[PoolStored]

Yes, it is reaonable.

 

[Newdude]

I just don't want this to get away from me while I am fiddling with settings.

#teamrunhot extends a cordial invitation to the club.

I fiddle with mine when it's outside of 8 to 12. If I happen to lose 2 extra ppm that day, I still have a full day or two FC in reserve.

Foul up at 5 to 7 ppm and you could be booking down the highway towards Swampville.

 

[kul]

I agree with @newdude being part of #teamrunhot has helped me recently when the weather is in the 90s and there’s full sun and I’m too lazy to pull my solar cover back on…

 

[rjb1211]

#teamrunhot extends a cordial invitation to the club.

I fiddle with mine when it's outside of 8 to 12. If I happen to lose 2 extra ppm that day, I still have a full day or two FC in reserve.

Foul up at 5 to 7 ppm and you could be booking down the highway towards Swampville.

Based on your previous comments I have been running it hot with the only downside being if I could trust the pH readings. The hot weather took me by surprise a little. I had bumped up cell output some but when I tested this morning the FC was down to 5.

I put it on superchlorinate and will check it later today. I will then back it off and test again tomorrow. Hopefully I get it dialed in again within a few days.

 

[Newdude]

I put it on superchlorinate

That's 100% for 24 hours and will make 4.5 FC for you, minus whatever burns off today.

5 is ok because you weren't playing kissey face with min, but anytime you find the FC needs a *now* boost, spike it right then and there with bleach. Then you have all the time in the world to fiddle with the SWG production.

Based on your previous comments I have been running it hot with the only downside being if I could trust the pH readings.

Sound like you read it right. Bravo. Also, it's your turn for snacks at the monthly meeting.

 

[rjb1211]

That's 100% for 24 hours and will make 4.5 FC for you, minus whatever burns off today.

5 is ok because you weren't playing kissey face with min, but anytime you find the FC needs a *now* boost, spike it right then and there with bleach. Then you have all the time in the world to fiddle with the SWG production.



Sound like you read it right. Bravo. Also, it's your turn for snacks at the monthly meeting.

I wasn’t going to leave it on superchlorinate for 24 hours, just while the sun was burning off chlorine during the day so it (hopefully) would get up to a higher level. I am going to back that off to 60% overnight and test again in the morning.

 

[Newdude]

I wasn’t going to leave it on superchlorinate for 24 hours

The point was that if you did it was only 4.5 FC, roughly 1 FC every 6 hours and not very much. If the sun burns off 2ppm from 10A to 4P, you're minus1. Food for thought.

 

[rjb1211]

The point was that if you did it was only 4.5 FC, roughly 1 FC every 6 hours and not very much. If the sun burns off 2ppm from 10A to 4P, you're minus1. Food for thought.

We are on the same page. I had set the cell at 65% around 10 am and at noon I was down a little. I then set it at 100% and at 5 pm was up 0.5 ppm. That was with high heat and bright sun.

I am going to leave it at 100% until later and then dial it back a little. I will check it in the morning and that should give me a good idea of how to set the cell for these conditions.

Edit: I think a better plan is to leave it on 100% for the 24 hours. It will then automatically go back to 65% and I can monitor from there.

 

[rjb1211]

The point was that if you did it was only 4.5 FC, roughly 1 FC every 6 hours and not very much. If the sun burns off 2ppm from 10A to 4P, you're minus1. Food for thought.

Thanks for making such a clear comment. It made me realize that I needed to have the FC well up before the bright sun started taking its toll so I left the cell on superchlorinate overnight. At 6 am FC was up to 7.5 as the math predicted and I expect it will be something over 8 by the time it goes back to the 65% I have the cell set at.

I will take a reading at that point and then again at 5 pm to see what happened over the course of the day. Hopefully I can just leave it at that tonight and test again tomorrow morning. That should give me a pretty good idea of the setting needed to maintain a good level.

 

[Newdude]

I will take a reading at that point and then again at 5 pm

Experiment to find your low fc point in the day. Then always consider the relation to it whatever time you happen to test. You did good