I have a couple of black dots on shallow end steps...they are like epoxy bumps. I would like to take an ice pick to them but refrain. Your CYA 70..maybe raise your FC a little higher but probably won't address the above waterline "nastys"
Ditto above..and we are in the hot fla sun. I think bird cage screen enclosure helps. I like the idea of SWG's but compared to $4.00 for 2.5 gallons of 10.25% LC (ACE hardware bulk) ..thats $1.59/ wk...well we'll stay with that for now. I am tinkering with a slow drip in pool liquid chlorine...
My pool and location similar to yours...8 inch drop and then rain topped it off brought my CYA down from 100 to 80. I keep FC in the 6 to 10ppm range. Water is xtal clear. PH does climb after these Fla rains..a little MA cures that.
"Chlorine lock is an industry term has no bearing here at TFP"....as quoted above..i used the phrase before but no more. For almost a year my CYA was 100 (now 60) as prior owner tabbed to much. Used TFP"s FC/CYA chart and set FC between 7 and 11ppm....water has always stayed clear.
SWG someday..LC 1.59/gallon 10.25% ACE hardware bulk..2.5 gallons last 2 weeks here in central fla. Screened enclosure helps. Half a minute every two days is easy maintenance. I can see some definite advantages with SWG esp if we go on vacation.
TF100 :) soon for us but for the last year and 4 months Aquachek 7 ways (CYA) have matched Pinch a Penny readings. I then use the TFP CYA/FC chart to set my FC...water xtal clear. We only use liquid chlorine(1.59 per gallon bulk local ACE hardware) and occasional muriatic acid after hard rains.