SLAMing colored plaster pool

[Jkhook70]

My 2012-built concrete/colored plaster (gray) salt water pool operated fine in 2012 and 2013 with the SWG. I didn't have to add any liquid chlorine at all either year. However, 2014 is a completely different story! With my SWG set at 100%, I have to add liquid chlorine all the time. It is as if my SWG is not operating at all. My pool installer even gave me a new IntelliChlor IC40, but it operates the same as the original one. I still have to add chlorine regularly to maintain FC

After reading some posts (I'm new to TFP) I'm thinking I need to SLAM my pool, as I have some signs of green algae growing in a few places, although the water remains pretty clear.

PoolMath says I need to bring my FC to 28 to SLAM the pool, which means I have to add over 4-1/2 gallons of 12.5% Sodium hypochlorite.

Where do I add this much chlorine? I have already discolored my tanning shelf with chlorine or acid by pouring over it.
What will this do to the colored plaster of the rest of the pool?
How long do I need to maintain that FC level?
How do I even test FC to determine if I'm at that level, as my tester only goes to 5! The SLAM instructions say I need to check the FC level regularly to maintain the high level.

Current numbers (yesterday, before adding 2 gal of liquid chlorine):

Temp. 83 degrees
Saturation index 0.2
TDS 286
CYA 70
FC 0.5
pH 7.4
Adjusted TA 104
Tot. hardness 430
Salt 3400

I long for the good old days of having the SWG handle my FC levels.

 

[Texas Splash]

Hello and welcome to TFP! You are correct - green means to SLAM. Regular liquid bleach is fine for your pool and equipment when added in the manner as described by the Poolmath calculator and the Pool School - Chlorine / CYA Chart. You add the bleach slowly near a return jet with the pump on for about 30 minutes. When you SLAM, you do so and “Maintain” it that way until 3 objectives are met:
1. Water is clear
2. You do not lose any more than 1ppm of FC overnight (that's the OCLT)
3. CC (Combined Chlorine) is <.5

To test FC at these levels, you need the proper test kit. Specifically for FC and CC, you need the FAS-DPD portions that can be obtained from TFTestkits.net. This is a VERY accurate method that far exceeds the capability of an OTO, strips, etc. Please see that site as it is a great resource for testing items. I use the TF-100 w/ speed stir and love it.

When you SLAM, you will turn-off or dial-down your SWG to save on cell service life. All the details are covered on the Pool School - SLAM - Shock Level And Maintain.

If you have any more questions, please let us know.

 

[YippeeSkippy]

I'd want to test your water directly coming out of the returns to determine if the chlorine is being produced properly. It should be higher in FC immediately out of the return than the FC in the rest of the pool.

 

[pooldv]

I had to SLAM about a month ago. I didn't raise my SWG output fast enough to keep up with the heat and swimming. I slammed for about a week and a half at 25-28 FC and CYA at 70. No issues with my dark pool bottom. We swam every day and brushed from inside the pool!

 

[Jkhook70]

I had to SLAM about a month ago. I didn't raise my SWG output fast enough to keep up with the heat and swimming. I slammed for about a week and a half at 25-28 FC and CYA at 70. No issues with my dark pool bottom. We swam every day and brushed from inside the pool!

You swam with the FC at 25-28? Sounds uncomfortable, to say the least!

 

[tim5055]

You swam with the FC at 25-28? Sounds uncomfortable, to say the least!

Nope, not at all. I swam at shock level 10 days ago and felt no difference between that and maintenance levels of chlorine. Shock level is hard on the swimsuits, not skin.

 

[Jkhook70]

Just curios - what kind of chlorine did you use, regular bleach or pool chlorine?

 

[pooldv]

Bleach, liquid chlorine and liquid shock are all chemically exactly the same. The only difference is the chlorine percentage. It is safe to swim with chlorine between minimum level and shock level for your CYA, Chlorine CYA Chart

My kids opened their eyes and didn't even notice. I made them wear goggles anyway in case there were any stray areas of combined chlorine where algae was getting killed. We swam for at least a couple of hours every day. No issues, really couldn't even tell other than the occasional hint of smell of CC.