Mess After Vacation

[ashley79]

Haven't checked in for a while as pool has been sparkly and clean.. Went on vacation last week and came back to yellow algae on walls in shaded end. There's been a ton of rain here too so that's compounded the problem, I'm sure. Do I need to slam? Is it possible it'd go away without doing that? My numbers:
FC 2.5
PH 9
TA 80
CH 190
CYA 65

I turned the SWG up to 70% from 50. Thanks as usual for any help.

 

[Meaty]

Yes, the presence of algae requires a SLAM

 

[ashley79]

Thanks very much, I've collected all of the supplies needed for SLAM and will start this evening.
Any ideas what specifically could've caused the outbreak based on info above? Would heavy rain be enough? Just trying to avoid this again this summer.

 

[s1njin]

Your chlorine is too low for the CYA level you have. http://www.troublefreepool.com/threads/2177-Chlorine-CYA-Chart

Your pH is too high period. http://www.bluescience.com/swimming-pools/posts/what-does-rain-do-to-pool-water/

 

[pooldv]

I've never seen PH test that can measure 9. It is very important to maintain PH between 7.2 and 7.8 at all times. 7.5 to 7.8 is better for your pool.

 

[ashley79]

thats my fault. it tested darker than the highest number on the kit so i put 9. it may be above that, but ive got plenty of acid to bring it down to slam. couple last qs.
is 2 hours enough time after adding acid to get a proper reading (pump on)?
does the algae have any effect on giving me a true ph reading?
since my pump will be running during the slam, is it ok to leave my robot in the pool? i dont have a manual vacuum.

 

[pooldv]

30 min should be enough. Algae has no I pact on the PH test. Yes, robot is fine.

 

[Meaty]

Your chlorine is too low for the CYA level you have. http://www.troublefreepool.com/threads/2177-Chlorine-CYA-Chart

Your pH is too high period. http://www.bluescience.com/swimming-pools/posts/what-does-rain-do-to-pool-water/

This caused ur issue

 

[max2k]

thats my fault. it tested darker than the highest number on the kit so i put 9. it may be above that, but ive got plenty of acid to bring it down to slam. couple last qs.
is 2 hours enough time after adding acid to get a proper reading (pump on)?
does the algae have any effect on giving me a true ph reading?
since my pump will be running during the slam, is it ok to leave my robot in the pool? i dont have a manual vacuum.

could you please add name of the test kit you use to your signature?

 

[ashley79]

added.
thanks to all for the info.

 

[ashley79]

Pools been clear but passed OCLT this morning; went from 24.5 to 23.5 FC. When will PH test be accurate again?

 

[pooldv]

Ph test is accurate with FC up to 10 ppm.