I’ve been a TFP member for several years but seldom post as I find my questions answered using the search feature, but my current situation has me confused.
I started a SLAM using pool store 10.5% sodium hypochlorite on my in-ground SWG vinyl pool, Aug. 12, due to persistant alge growth on the sides and bottom. The water was clear, but never what satisfies me clear and sweeping clouded it. Before starting, I got the chemistry in line with all specs. (ph 7.8, alkalinity 100, CYA 50) Except Calcium hardness, which from what I read here is not very important in vinyl. My CYA was at 50, so I broght my chlorine level above 26 (fresh Taylor DPD powder & R871 ) and maintained it at that level for 8 days. I completely brushed and/or vacuumed to filter every day. I backwashed when the pressure rose 20% above its lowest reading The water cleared more each day and I got consistant 2 ppm OCLT readings each morning before the sun hit it. I never got a CC reading above .5, usually they were 0. The only swimmer was me, brushing from inside with snorkel & mask. I brushed everything, even inside the returns with a toothbrush. On Aug. 22, my OCLT reading was 1 ppm fc/ 0 cc. I stopped brushing and let the chlorine level drop naturally. When the FC reached 14, I turned my SWG on at 15% to insure it stayed at a safe level during the full sun hrs. The water was Gin clear (it still is). I noticed sediment collecting in the indentations in the bottom right from the first day of 0 OCLT, but did not see the need to vacuum as I thought it was airborne particulate, surely not possible to be alge after the SLAM? There has been no swimmers except me since Aug. 12 and my morning chlorine tests show a steady, consistant FC loss, and has never been less than 9 ppm (yesterday).
Pump was run 24/7 during the SLAM ,rpm 8 hr. 2500 / 8 hr. 2000 / 8 hr. 1200. The SWG was off The pool is in full sun in Aug. from 11AM to 2pm, ½ sun the remaining daylight hours. Water temp. in Aug. was low 80’s.
What/why/how can this algae be so persistant? And grow at FC above 10ppm? My pool vitals are in my sig.line.
I have tried to make this as brief as possible while giving all data that could provide a good answer. I’ve had this pool 22 yrs. (new liner & SWG in 2022) and always fighting alge. The pool next door is poorly maintained (SWG), slightly cloudy and NEVER has visible alge on sides/bottom. Thank You
NOTE: OPD was NOT used during SLAM, only DPD.
I started a SLAM using pool store 10.5% sodium hypochlorite on my in-ground SWG vinyl pool, Aug. 12, due to persistant alge growth on the sides and bottom. The water was clear, but never what satisfies me clear and sweeping clouded it. Before starting, I got the chemistry in line with all specs. (ph 7.8, alkalinity 100, CYA 50) Except Calcium hardness, which from what I read here is not very important in vinyl. My CYA was at 50, so I broght my chlorine level above 26 (fresh Taylor DPD powder & R871 ) and maintained it at that level for 8 days. I completely brushed and/or vacuumed to filter every day. I backwashed when the pressure rose 20% above its lowest reading The water cleared more each day and I got consistant 2 ppm OCLT readings each morning before the sun hit it. I never got a CC reading above .5, usually they were 0. The only swimmer was me, brushing from inside with snorkel & mask. I brushed everything, even inside the returns with a toothbrush. On Aug. 22, my OCLT reading was 1 ppm fc/ 0 cc. I stopped brushing and let the chlorine level drop naturally. When the FC reached 14, I turned my SWG on at 15% to insure it stayed at a safe level during the full sun hrs. The water was Gin clear (it still is). I noticed sediment collecting in the indentations in the bottom right from the first day of 0 OCLT, but did not see the need to vacuum as I thought it was airborne particulate, surely not possible to be alge after the SLAM? There has been no swimmers except me since Aug. 12 and my morning chlorine tests show a steady, consistant FC loss, and has never been less than 9 ppm (yesterday).
Pump was run 24/7 during the SLAM ,rpm 8 hr. 2500 / 8 hr. 2000 / 8 hr. 1200. The SWG was off The pool is in full sun in Aug. from 11AM to 2pm, ½ sun the remaining daylight hours. Water temp. in Aug. was low 80’s.
What/why/how can this algae be so persistant? And grow at FC above 10ppm? My pool vitals are in my sig.line.
I have tried to make this as brief as possible while giving all data that could provide a good answer. I’ve had this pool 22 yrs. (new liner & SWG in 2022) and always fighting alge. The pool next door is poorly maintained (SWG), slightly cloudy and NEVER has visible alge on sides/bottom. Thank You
NOTE: OPD was NOT used during SLAM, only DPD.
