Installed SWG and tested water chemistry yesterday for the first time since fall of last year. (Early April is usually my first spring test, when the water temperature is in the mid 50's.) FC level was down to 0, which is not unexpected, and not too alarming as long as chlorine is introduced soon enough. (I am right about that, aren't I?) Just to be safe, I added two gallons of bleach, enough to add about 11 PPM of FC and turned on my SWG at 100%. Over the last 19 hours, the FC level has dropped from 16 to 15, even though the SWG is adding FC at a little over 1 PPM per hour, but it doesn't seem like the FC consumption is due to algae because CC is <0.5 PPM and filter pressure has increased less than 1 PSI. It's like my CYA is at 0! (I can't test CYA until I receive the replacement test tube I ordered last night when I couldn't find it.) It is inconceivable that CYA could be that low. I keep it >100 during pool season (I know the risks), and it is usually 70-80 when I first measure in early April. Am I correct in assuming that if algae is the reason the high rate of FC consumption, I would have measurable CC as well as significant increase in filter pressure? Am I missing something?
In case it is relevant, I just leave my solar cover on the pool in the winter. Old winter cover shredded years ago and the solar cover was dirt cheap (<$30 when I bought it on Amazon so I bought 3 and the first one lasted 3 years doing that). At least it greatly reduces the amount of leaves and dirt that get in during the off season. Pool is still covered, and a little algae had bloomed on the edges where the sun heats up the little puddles on the surface of the cover. (I really need to start tending to the pool in mid-March.) I haven't removed the cover completely to get an idea of cloudiness of the water, but I pulled one corner back far enough to confirm that, as usual, it's pretty clear. The dirt and leaves are my main obstacle.
Edit: The only other explanation I can think of is that SWG cell died over the winter, but I'm assuming their production slows down gradually, as opposed to just suddenly stopping, and it seemed to be still going strong at the end of last season. This is my first cell, so I haven't seen one "die" yet.
In case it is relevant, I just leave my solar cover on the pool in the winter. Old winter cover shredded years ago and the solar cover was dirt cheap (<$30 when I bought it on Amazon so I bought 3 and the first one lasted 3 years doing that). At least it greatly reduces the amount of leaves and dirt that get in during the off season. Pool is still covered, and a little algae had bloomed on the edges where the sun heats up the little puddles on the surface of the cover. (I really need to start tending to the pool in mid-March.) I haven't removed the cover completely to get an idea of cloudiness of the water, but I pulled one corner back far enough to confirm that, as usual, it's pretty clear. The dirt and leaves are my main obstacle.
Edit: The only other explanation I can think of is that SWG cell died over the winter, but I'm assuming their production slows down gradually, as opposed to just suddenly stopping, and it seemed to be still going strong at the end of last season. This is my first cell, so I haven't seen one "die" yet.
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19 hours of SWG @ 100% produces 10.5 PPM of FC, and FC went up from 8 to 15 in that 19-hour period. I'd say low temp easily accounts for 67% production rate. Also, doesn't salt contribution also affect SWG production? Salt is near low end of recommended concentration. Headed out now to turn off the SWG and measure FC for OCLT!