I'm wondering if the output of my SWG is correct. I'm looking for a sanity check on my math:
My water chemistry today was (evening measurement time):
CC 0.5 (or less)
Borates 40 to 50
CYA 70 to 80 (between 70 and 80 on the black dot/graduated cylinder test)
Salt - 3000 ppm
The FC was 5.5 at 8:15 AM before the sun hit the pool. It was basically sunny with a max temp of 82F. The pool saw sun from 10:00 to about 5:30 to 6:00.
I ran the system 10 hours last night from 9:00 PM to 7:00 AM. It is an all or none system (no ability to regulate FC generation as a percentage).
The specs for the SWG state a maximum sanitizer output of 11 grams/hour. So the amount of chlorine (assuming 100% efficiency) would be 110 grams. Therefore, for my current chemistry, using the pool math calculator (set to chlorine gas - mass is mass), it appears I should have had a gross FC rise (assuming zero consumption overnight) of approximately 5.8 overnight. YET, my FC was 5.5 this AM and 2.5 the night before for an estimated generation of 3.0 FC (assuming no overnight losses). The CC is very low, so I can't believe what is basically an OCLT would say I'm losing 2.8 FC overnight! So, obviously, my SWG isn't putting out chlorine efficiently. In fact, the numbers basically say the output is only (3/5.8 x 11) or 5.7 g of Cl per hour run-time. The unit is less than a month old, and appears to be clean. The manual's statement on the SWG is:
"The titanium electrode and E.C.O. electrodes have a self cleaning function incorporated into the electronic control’s programming. In most cases this self cleaning action will keep the electrodes working at optimum efficiency. If the pool water is hard (high mineral content) the electrodes may require periodic manual cleaning. To maintain maximum performance, we recommend that you open and visually inspect the titanium and E.C.O. electrodes once per month."
I don't appear to have hard water, unless they are talking about other minerals beside calcium.
The specs for the pump/SWG system cover up to a 14K gallon pool and our is only 5K gallons. In fact, the manual specifies an 8 hour SWG run time for a 14k gallon pool (at 84 to 97F ambient air temp). So, I cannot see how this thing could keep up with a larger pool (it's maximum SWG run time is 12 hours).
Any thoughts? Am I missing something? Could my SWG be defective?
The manufacturer's "ideal" salt level is 3000 ppm (I measured 3200pm about 1.5 weeks ago, it is 3000ppm today), and I know the TFP guidance is to run the salt about 400 ppm higher than spec'd, but could this be a contributing factor to what appears to be poor FC generation? The rest of the chemistry numbers seem to be good to very good.
PS - I forgot to confirm the FC drop during the day today was 2.5.