low free chlorine

[aussieta]

is it possible for the chlorinator to show an output but not actually be working?
have a lincoln SWG, shows around 68% fluctuating with air bubbles
last thing before FC drop was add 4kg balpak 300 (calcium) hardness was 120 increase to 170
FC dropped to 1.6ppm, 0ppm CC, from a steady 3.6ppm FC and got a tiny amount of algae over a two week period
added cal/hypo as have low calcium 170ppm
after a couple of days holding FC at 18ppm, water was spotless and algae gone
stopped using cal/hypo and FC dropped to 8ppm in two days

10 january added 4kg calcium after test
TA 90, ph 7.4, hardness 120, FC 3.6, CC 0, cya 70

24 january found low FC
TA 90, ph 7.4, hardness 170, FC 1.6, CC 0, cya 70

25,26,27 january during cal/hypo use
TA 90, PH 7.5, hardness 180 FC 18, CC 0, cya70

this test 29 january, stopped using cal/hypo on 27 january,
TA 90, PH 7.5, hardness 180 FC 8, CC 0, cya 70
added more cal/hypo after test just in case chlorinator is faulty

i realise an overnight chlorine loss test would help but i don't live at the property

 

[Patrick_B]

You could say that's a 5 PPM FC loss each day. Considering it is hot summer there, I wouldn't say this is too bad.

Has anyone been using the pool on those days at all?

It sounds like you have a good understanding of things and yes an OCLT would be a good idea if you can arrange it.

 

[aussieta]

that was with chlorinator running which made me expect virtually no loss
pool is geting heavy use atm

 

[Patrick_B]

Yo should always expect loss on a daily basis, especially with heavy, or even moderate use. Still doesn't sound bad to me at all.

 

[aussieta]

performed overnight chlorine loss
9pm 13.5FC
6am 13.5FC
so that was a nice surprise

local pool shop suggested a few things to see if chlorinator is working
if cell is in a clear housing look for bubbles/cloudy water coming out of cell
measure FC in pool and directly from return jet to see difference

measured tonight 4pm
in deep end 10FC
from return jet 11.5FC
so appears SWG is working just not sure how efficiently
have added another 3 hours to pump run time and increased output to 90%