Hi; I just joined, and while I have spent some time reading through forum posts and educating myself, I have some special circumstances, and would appreciate some advice on the best way to maintain FC levels.
I have three pools, one 20' x 40' in New England, and two much smaller 12' x 18' pools on St. John, in the U.S. Virgin Islands. This post is focused on the two smaller pools. Both homes are short-term rentals, and nearly fully booked year-round. They get weekly service by pool maintenance guys, but I have concluded that their approach to pool chemistry is all wrong. They mostly use tri-chlor tabs, but since there is no winter drain down, the CYA levels are off the charts, which also requires very high FC levels. I recently bought a Taylor K-2006 test kit, but I would have to dilute the pool water to even get a reading on the Taylor test.
It would be nearly $500 per pool to dump the pool water and start over, but I am considering doing this. I like the bleach, baking soda, and borax approach. The only intervals for pool service are weekly, so if the FC levels would drop too far during a week, some automated way to add chlorine would be needed. A mid-week service visit is another option, but that would be pricey. While the pools are small (6500 gallons), it is very sunny, and we use solar pool heaters to keep the water temperature in the low to mid eighties. Electricity is expensive (52 cents a kW-hr), so I use a variable speed Pentair pump set to a fairly low RPM (1500). I have flow meters, and this pump operating from 9:30 AM to 4:30 PM (when the solar heaters receive sun) is enough to move all of the water through the filter once each day. I am aware of SWG's, and while a small one wouldn't use that much electricity, they would lower pH, and appear prone to technical issues that the local pool guy would not be able to diagnose or address.
My questions are as follows:
Would a once a week application of liquid bleach work, or would some more frequent delivery method be necessary?
What daily decline in FC levels should I expect?
Could a once a week application of bleach or liquid chlorine serve as a shock, and still have enough FC level left one week later?
Would an increased level of CYA help in this case? I see recommendations of 40 ppm. What level would work best?
Is there any anti-algal value to adding salt in the absence of an SWG?
Should I hook up a peristaltic pump and add liquid chlorine that way?
Or should I use an SWG and simply plan on regular replacement of the cell before it can decline in effectiveness?
Thanks in advance!