Questions before a SLAM

ba67

Active member
Oct 17, 2018
34
Southern Kentucky
I just opened up our pool. The water is greener than usual because I opened the pool so late. Pool is surrounded by trees so I blindly tried to get the leaves out of the pool that blew under the cover, but I may have missed some since I can't see the bottom. Here are our test results:

Chlorine - 0
CC - .5 (how is that possible since it is a swamp?)
TA - 40
PH - either 7.8 or 8.0
CYA - appears to be 0 (but pool store says it is 20 so 0 might not be accurate.)
CH - 160

I've got some Dichlor shock that I'd like to use up so I'd like to start off with Dichlor shock to quickly increase the CYA instead of going out and buying stabilizer. After I add enough Dichlor to get the CYA to 30, I will begin the SLAM with liquid chlorine. Before I start adding anything to the pool, I have a few questions.

1. According to pool math, 3 pounds of Dichlor will increase CYA by 9.5 which will get the CYA close to 30 if the pool store's test of 20 is accurate. If not, I will add more Dichlor until the CYA gets to 30. How long will I need to wait after adding the Dichlor before the CYA will show up on my test? I'm just not sure how accurate the CYA test is because my reagent expired on 2/20 so I'm wondering if the pool store's test of 20 is actually more accurate than my test of 0.

2. Since 3 pounds of Dichlor will lower PH by .4 according to pool math, and the PH is currently 7.8 or 8.0, should I wait to add the muriatic acid to lower the PH after I add the Dichlor? If so, how long do I need to wait after adding the Dichlor to get an accurate PH reading so I will know how much muriatic acid to add? And how long do I wait after adding the muriatic acid before starting the SLAM with liquid chlorine?

3. Do I need to increase the TA since it is 40 to protect my heater? If so, should I add the baking soda before I start using the Dichlor or wait until after I add the Dichlor and I start the SLAM with liquid chlorine? If I need to increase the TA, what TA number should I shoot for?

4. Since there is a tree that is dumping seeds into the pool, should I increase suction to the skimmer instead of keeping it at 50% skimmer/50% MD? I'm worried about the filter getting clogged because of all of the algae and seeds, so I wasn't sure if this was a good idea or not.

5. Do I wait until after the SLAM is over to increase the CH level? Could my heater be harmed by running the pool with that low of a CH level?
 

YippeeSkippy

Mod Squad
LifeTime Supporter
Jan 17, 2012
17,100
Evans, Georgia
Its truly very hard to discern a CYA level of 20..... they're just tossing out a number. Add only enough dichlor that it will give you 10ppm CYA. Give it time to mix in and dissolve and then retest. See if you get 30ppm or not? Can repeat. Truthfully I don't know how quickly dichlor's CYA shows up?

I still would trust your result over theirs. Order replacement here - www.tftestkits.net

Take TA up to 60 now w/ baking soda. Take it down also with muriatic acid. Don't use dry acid.

Get a Skimmer Sock or one of those disposable hair covers lunchroom ladies wear. Amazon carries them pretty cheap. This lets you collect the tree debris before it gets to your filter.

Don't run heater yet and don't worry about CH till after the SLAM process.

Maddie 🐞
 

ba67

Active member
Oct 17, 2018
34
Southern Kentucky
Its truly very hard to discern a CYA level of 20..... they're just tossing out a number. Add only enough dichlor that it will give you 10ppm CYA. Give it time to mix in and dissolve and then retest. See if you get 30ppm or not? Can repeat. Truthfully I don't know how quickly dichlor's CYA shows up?

I still would trust your result over theirs. Order replacement here - www.tftestkits.net

Take TA up to 60 now w/ baking soda. Take it down also with muriatic acid. Don't use dry acid.

Get a Skimmer Sock or one of those disposable hair covers lunchroom ladies wear. Amazon carries them pretty cheap. This lets you collect the tree debris before it gets to your filter.

Don't run heater yet and don't worry about CH till after the SLAM process.

Maddie 🐞
Thanks for the advice. Are you saying that I should go ahead an increase the TA to 60 now, and then lower the PH with muriatic acid, before I add the Dichlor? Or should I increase the TA to 60 now, add the Dichlor, test the PH (since Dichlor might lower it) and then add the proper amount of muriatic acid to lower it to 7.2 before starting the SLAM with liquid chlorine? I would prefer to add the baking soda and Dichlor tonight, retest the PH in the morning, add muriatic acid to lower the PH, and start the SLAM tomorrow when I'm going to be home all day to test and add chlorine. Does this sound like a good plan?
 

IceShadow

Gold Supporter
TFP Guide
Jun 8, 2019
2,611
Milwaukee, WI
Pool Size
20000
Surface
Vinyl
Chlorine
Liquid Chlorine
Get TA up first, go ahead and add some dichlor (undershoot your CYA to start), and then test the pH. :)
 
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