lower PH first or SLAM?

[tobydog]

My pump was not working for two weeks while I waited for a warranty repair. I was able to keep the FC at or above 7 (CYA of 80) and the water stayed clear for about the first week. After that, the water began to turn green. I upped the FC to well above 10 and the green never really got worse. The repair was completed on Friday so I have been running the pump ever since. It was amazing how clear/clean the pool looked after only running over night.

I tested the water yesterday and got the following results:

FC - 17.5
CC- 0
TA - 110
CH - 290
CYA - 80
PH - ? The reading showed over 8, but I understand that it is not accurate with FC over 10.


Today, the FC was 13.5 and CC was less than .5. Again, the PH read high.


Question is.... should I give it the rest of the day for the FC to get below 10 so I can get an accurate PH? I want to bring the FC to SLAM to make sure there isn't anything hanging around.

 

[YippeeSkippy]

The first step in a SLAM procedure calls for you to lower the pH to around 7.2 because once you add chlorine and your FC is greater than 10, the pH test is not accurate.

Let your FC drop and if necessary get on that pH with some Muriatic Acid, re-test in 30 min after its mixed in and if you need to re-dose do it and once you get the pH fixed start your SLAM.

 

[tobydog]

Sounds like a plan. Also, are my numbers acceptable or is there something that needs adjustment after the SLAM?

 

[YippeeSkippy]

Give us the most current #s:
FC
CC
pH
TA
CH
CYA

 

[tobydog]

Same as above, except the FC is 10.5.

 

[YippeeSkippy]

Your CYA is kind of high for a SLAM (only because it requires more chlorine then) but being in California I wasn't sure you had the ability to lower the CYA by draining some water and replacing it with fresh? If that's a possibility it really helps. If not, you'll just need to buy more bleach.

The only parameters to deal with at the start of a SLAM is CYA, the pH and FC/CC. Get that pH fixed and then SLAM away!

If anything else was wonky it could be dealt with later, although as you lower your pH with MA it will also lower your TA some which isn't a bad thing.