Starting SLAM today post ~50% drain. Start process after refill?

Flying Tivo

Well-known member
Jan 24, 2017
1,885
Monterrey, NL, Mexico
Pucks will raise CYA very slowly, I suggest buying CYA conditioner and adding to raise to 30 before starting the slam. Dont worry if you overshoot 30 by a little, since you are in TX you will. probably need around 40-50 in the full heat of summer. You should plan on using only liquid chlorine for sanitation, leave the pucks for special occasions like vacations.
 

linzi618

Active member
May 11, 2017
42
Pflugerville, TX
You can begin your SLAM Process now. Lower your pH and begin by adding 12 ppm of liquid chlorine ASAP.



Every 8 oz Trichlor puck will add 2.7 ppm or FC and 1.7 ppm of CYA and lower pH by 0.15 to your 20,000 gallon pool.

It will take 10 tablets or so to get you around CYA 30.
Ok great! So I don’t need CYA to be within range to start the SLAM, and am looking at several days before my CYA comes to range so I need to babysit FC since it will probably be used up quickly. The MA has already brought my pH down to about 7.2.
 

linzi618

Active member
May 11, 2017
42
Pflugerville, TX
Either way is ok as long as you know you will be loosing FC to the UV rays of the sun until you have the proper FC/CYA Chart.
So pool math is telling me to add 51 oz of my 12.6% liquid chlorine to reach target FC of 3. The SLAM chart says SLAM FC should be 12 so do I need to adjust the target FC in the pool math app to 12 to get my appropriate amount chlorine to add?
 
  • Like
Reactions: Flying Tivo

ajw22

Gold Supporter
TFP Guide
Jul 21, 2013
19,400
Northern NJ
So pool math is telling me to add 51 oz of my 12.6% liquid chlorine to reach target FC of 3. The SLAM chart says SLAM FC should be 12 so do I need to adjust the target FC in the pool math app to 12 to get my appropriate amount chlorine to add?
There is a slide toggle by the FC recommendation in PoolMath for SLAM that changes the target. Look for it.
 

mknauss

Mod Squad
TFP Expert
Bronze Supporter
May 3, 2014
32,549
Laughlin, NV
Have you read the SLAM Process?
Be sure to follow it.
Lower pH to 7.2.
CYA at 30 ppm or bit higher.
Test and add LC at least 3-4 times per day to start, 2 times per day once your FC loss slows.
 

linzi618

Active member
May 11, 2017
42
Pflugerville, TX
And do not use trichlor during the process. That makes your pool water more acidic and increases CYA.
I have read it a few times now. I put the tabs in because my CYA is so low it doesn’t register in my view tube. I feel like I’d rather babysit all the parameters while waiting for the pucks to bring my CYA up to suggested levels as opposed to having to go to Leslies and buy CYA increaser, which would feel like a gut blow since we just essentially changed our water twice to get rid of the sky high CYA! I know the consensus here is that tri-chlor is the devil but I’m trying to find a good half-way point between the process on here and my pool builder’s recommendations (unlike Leslies they obv don’t have skin in the game). I promise if I’m back here sooner rather than later with CYA problems yet again I will tag you and eat crow! My pool is already looking spectacular but of course I’m going to operate via test results, not observable beauty. I very much appreciate each and every bit of advice I’m getting here as this is my very first time using good testing and not relying on Leslies for water testing/chemical recommendations.
 

linzi618

Active member
May 11, 2017
42
Pflugerville, TX
3 hours in -
pH - up to 7.5 (should I add MA again to bring back down to 7.2?)
FC - holding at 10ppm
CC - 1ppm (down from 1.5)
TA - 130 (down from 160...is this the parameter that is unreliable to test mid-SLAM?)
CYA - Obv still 0

Water crystal clear and walls of footwell in spa that were discolored before look 99% better already! Have brushed every surface copiously and the Polaris is taking care of the pool floor. Baskets cleaned. My filters were last hosed to clean about a month ago before this whole process during the algae problem. Will probably have hubby clean them again once done.
 

ajw22

Gold Supporter
TFP Guide
Jul 21, 2013
19,400
Northern NJ
Once you begin the SLAM Process just test FC and CC.

Test your CYA every few days. If you stay with Trichlor it is going to take up to 2 weeks for your CYA to get to 30. No reason to waste reagents until you go through at least 10 tablets.

Do an Overnight Chlorine Loss Test every night and see how much FC you lose. You might not need a long SLAM Process with mostly fresh water.
 
  • Like
Reactions: linzi618

mknauss

Mod Squad
TFP Expert
Bronze Supporter
May 3, 2014
32,549
Laughlin, NV
Last question for now - when will it be safe to swim? It’s going to be 97 here today but we can avoid if necessary!

You can safely swim in a pool as long as the FC is above the minimum and at or below SLAM level based on your CYA. You must also be able to see the bottom of the pool in the deep end of the pool.

The SLAM level for your CYA is 10 ppm. Though it will be quite harsh to swim in. You need your CYA up to 30 ppm for comfortable swimming at SLAM level FC.
 

linzi618

Active member
May 11, 2017
42
Pflugerville, TX
Have just tested again and my FC is now down to 4.5 (from 10) and CC down to 0.5 (from 1.0).

My husband is out getting liquid conditioner to bring the CYA up some. Am I correct to wait until we’ve added the conditioner to do another chlorine add so we bring the SLAM FC level up to the proper CYA:FC ratio? How long is it necessary to wait after adding the conditioner to do the bleach add?

Edit: removed calcium hardness question: I am in recommended range.
 

ajw22

Gold Supporter
TFP Guide
Jul 21, 2013
19,400
Northern NJ
Keep the chlorine up and add the conditioner when you get it.

208 oz of liquid conditioner will raise your CYA from 0 to 30. Remove the tablets so it does not take your CYA higher.

What is your CH? Don't start using cal-hypo. Stay with liquid chlorine.
 

linzi618

Active member
May 11, 2017
42
Pflugerville, TX
Overnight test passed!
Yesterday evening at 7:15 PM - FC 10; CC 0.5
This morning at 10:10 AM - FC 9.5; CC 0.5

I believe this SLAM is done, correct? Do I wait for FC to come down to normal ranges to balance pH and alkalinity or can I start now?
pH 7.8
TA 170
 

mknauss

Mod Squad
TFP Expert
Bronze Supporter
May 3, 2014
32,549
Laughlin, NV
Pool water is crystal clear, right?

If so, nothing to do. Keep your FC in target range based on your CYA. When pH reaches 8, add acid to lower it to 7.6.
TA needs no chemical adjustment. Test it once per week and record it. The value is needed to calculate how much acid you use when you lower your pH.