Warmer pool - SWG not cutting anymore?

[samotlietuvis]

After I expanded my solar eating pads, my pool never drops below 84F in the morning, and it gets up 90F at 5pm. Nice for enjoying the pool , but algae appears to like it too . I been testing my FC for the last 3 weeks, and it is hanging between 1ppm and 1.5ppm, my CYA is at 35. Unfortunately I observed a few speckles of mustard algae in shaded area, but the water is crystal clear. I run my pump 10hr per day and the SWG is working well (can see small bubles). Per specs, my salt system should be producing 0.3ppm Cl/hour, which equates to 3ppm of Cl per 10 hours of running.

I started adding 2 gallons of Chlorine once per week on Tuesday for the last two weeks - no sign of mustard algae so far. Just tested my FC this morning, Sunday, and it is at 1.5ppm, Ph at 7.6. Got two more days to go before I add 2G of Chlorine. It appears that my pool is loosing ~3ppm of Cl/day that the salt system is generating, and that I need supplemental Chlorine to keep algae at bay.

Anybody else needs to add supplemental Chlorine when pool gets very warm and Salt system does not cut it?
Or should I SLAM and kill whatever residual algae there is that is eating my Chlorine?
Is there any guideline how much extra Chlorine does pool need per 1F increase in temperature above 80F?

 

[mknauss]

A CYA of 35 for a SWCG pool in the SW desert is not a good idea. You are not even above minimum FC based on [FC/CYA][/FC/CYA]

You should first do a Overnight Chlorine Loss Test. Then SLAM Process if necessary.

Once you know you do not need to SLAM Process, you should raise your CYA to at least 70 ppm and follow [FC/CYA][/FC/CYA]

- - - Updated - - -

The FC loss is due to UV impact on the surface of the pool and organics. The temperature of the water does not have an appreciable impact on the FC consumption.

 

[samotlietuvis]

A CYA of 35 for a SWCG pool in the SW desert is not a good idea. You are not even above minimum FC based on [FC/CYA][/FC/CYA]

You should first do a Overnight Chlorine Loss Test. Then SLAM Process if necessary.

Once you know you do not need to SLAM Process, you should raise your CYA to at least 70 ppm and follow [FC/CYA][/FC/CYA]

- - - Updated - - -

The FC loss is due to UV impact on the surface of the pool and organics. The temperature of the water does not have an appreciable impact on the FC consumption.

I see. Never done OCLT - but I will do it Tuesday after I add 2G Cl in the evening, circulate for a few hours, measure my FC in the evening, run pump all night with SWG off, and then measure in the morning.

I thought higher temp means faster moving molecules that leads to faster leaving Chlorine. But since it is sun / organics, then higher temperature has nothing to do with my Chlorine leaving.

 

[samotlietuvis]

Found my algae culprit - had this fish shaped water thermometer bought from Walmart. It would be yellowish all the time, even if I pour 10% Chlorine inside, the yellow would come back in a few day. So this cheap thermometer would move around and seed my pool in algae. Removed the thermometer 1 month ago and have not added any supplemental Chlorine since.