FC seems low

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O

Omnipotent

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Jul 12, 2013
97
Clarksburg, MD
Guys, running Aquapure 1400 with Jandy E-Pump @ 1750RPM for 4 hours a day (0630 - 1030). According to the Jandy calculator this is enough for one turnover per day. I'm running at 60% on the Aquapure controller, and my salinity is at 3.2.

So when I test after the 4 hour run time (today tested 4 hours after run time ended 2:30) my FC was 1, maybe 1.5PPM. However when I turn the RPM up to 2750 in the evenings (when fountains and bubblers are on) and check again after swimming (2-3 hours) my FC reads 5-7PPM.

What I'm trying to figure out is does RPM affect how much Chlorine is added to the water? I'm guessing the answer is yes, as more GPM are flowing therefore more Chlorine would be deposited...but I'm just looking to confirm.

As well, for those of you whose pools are in full sun all day, how long do you need to run your SWG to maintain FC of 5-7PPM? Should I extend run time at 1750RPM for 8-10 hours? just trying to get this thing dialed in and I know all pools are differnt but looking for some ideas and starting points to accelarate the learning curve.

Thanks as always
 
No the RPM does not affect the output of the SWG. If there is enough flow, then the SWG will generate at the % setting. BUT, if the flow is too low, the SWG will not generate at all (it should show a low flow light or something).

Post up a full set of test results. Specifically, what is your CYA?
 
There is no way you are turning over 21k gallons at 1750 rpm in 4 hours. At that speed, I would guess you are getting somewhere around 25-40 GPM. Doing the math, that is less than 10k gallons turned over. I would suggest running the pump for 8-10 hours per day at 1750.
 
turn over is meaningless. You need to run the pump long enough to filter out the dirt and keep the pool looking clean ... AND ... you need to set the SWG to maintain adequate FC. If it is not, then you should be adding bleach to make sure the FC does not drop too low until you get the SWG dialed in.

See: How to Determine Pump Run Time
 
jblizzle said:
turn over is meaningless. You need to run the pump long enough to filter out the dirt and keep the pool looking clean ... AND ... you need to set the SWG to maintain adequate FC. If it is not, then you should be adding bleach to make sure the FC does not drop too low until you get the SWG dialed in.

See: How to Determine Pump Run Time
Click to expand...

Agreed - I was addressing the OPs reference to completing a full turnover in 4 hours. Regardless, I personally recommend an 8 hour run time, not just for filtration and allowing the Salt cell adequate time to produce chlorine, but also allowing the skimmers time to keep skimming the pool during the daylight hours.
 
I'm calculating that you are only adding 2 ounces of chlorine gas a day which equals .7 ppm of FC a day while you are running for only 4 hours with the SWG set to 60%.

As Jblizzle stated the RPM does not matter as long as there is enough flow to not produce a "No Flow" error. The SWG will not make more chlorine on a higher speed.

You need to increase the run time and/or the SWG% to make enough chlorine for the pools needs.

The math for the SWG:

Max chlorine output is 1.25lbs or 20 ounces of chlorine gas when the SWG is set to 100% and runs for 24 hours.
4hrs/24hrs = .1667 for run time hours in a day
60% setting = .6 for output of SWG
20 X .6 X .1667 = 1.992 ounces of chlorine gas in a day
Using PoolMath enter 21,000 gallons for your pool and enter 2 ounces of chlorine gas in effects of adding chemicals and you get .7 ppm of FC.
 
Based on pings excellent math ... you need to likely triple that output.

But being so low for now could mean you have algae growing. So using bleach to raise the FC and doing an OCLT would be a good first step to see if you now need to SLAM.
 
OK guys, thanks. I've switched to running 12 hours from 1030 PM to 1030 AM, any issue with running at night? Just seems to make sense when rates are cheaper (assuming rates are cheaper, I've not checked). I have kept the setting at 60% for now and will see where we end up tomorrow. I have/had been adding bleach when it got low, so it's only been in the 1-2ppm for the last day or so while I tried to rely on the SWG. Will check in the morning what it is and get back to you...as for SLAM, I'm heading on vacation on Sat so that's likely not an option before then but hopefully I can get the SWG to start raising the FC in the next day or two and then dial it back when we get home.

For the record pool has been crystal clear for the 45 days we've had the pool, 35 of those using the TFTP method. Now just gotta get the SWG dialed in.

Edit -
Reread above and can/will do OCLT tomorrow night after seeing what FC is in morning after the 12 hour run time.
 
Update, ran SWG @ 70% last night for 12 hours (only 10 so far, has 2 more left) and tested this morning...good news SWG works well. Drop Test = FC 11.5. So kicked % back to 60 and will see what that does tomorrow am.

Also will test at end of day to see how much FC is loss due to sun, though it might be a cloudy day today.

BTW, didn't see this answered....does it matter if you run the SWG for 12 hours at night vs daytime?
 

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FC of 10.5 with CYA of 60 isn't high at all. For a manually chlorinated pool, that would be at the high end of normal. Basically all you're doing is over-running the pump and swg a bit, but he chemistry is plenty safe. Bottom line, I see nothing wrong with leaving it for the week and dialing it in when you get back.
 
It is safe, but not necessary. I target 5-6 for my FC since you don't have to keep FC as high with a SWG.

I run my SWG for 12 hours at 80%. I'll be testing today, and I bet I have to raise that too.
 
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