Near Immediate Loss of Clorine

[mileurjl]

Two days ago I dumped in 6.75 gallons of 11.5% NaCLO to shock my pool and try to clear out the dead stuff so my IC40 SWG could keep up in an 18K gallon pool. With salt, CYA, TA, and pH all in the normal range, the first 6.75 gals didn't even register on the Cl meter, but seemed to clear the light green haze. Ran the pump all night and next day. Next afternoon, Free Cl was back down below 1.0, total Cl was still +.5 greater, so I dumped in the rest of the 15 gal barrel. I got a "HI" spike on the Color Meter, validated with the hardware store manual test kit, but within an hour, was back down in the low single digits. Left the pump/SWG running all night at 100%, checked again this afternoon; Free Cl = .16, Total Cl = .24, water clear and blue (Borated with 20-mule team many months ago). All three days have been somewhat overcast and pool tem about 80 - 85.

Tested the pump return and got 2.4 & 3.2 for free and total Cl. New IC40 back in Aug. I've been floating Tri-chlor/Tri-azine tabs in an effort to supplement the IC40. I also use Algimycin 2000 and Sea Klear Problem Klear for algae control.

Any ideas?

18K, 1" tile, IC40 SWG, Borated, Hawaii-Oahu

 

[jblizzle]

Welcome to TFP!

If you see green, then you need to follow the SLAM process that is described in Pool School. This is usually done without the SWG even on as it just can not generate enough FC fast enough to eliminate the algae.

Please post all your test results. The required FC is a function of your CYA level, so it is imperative that you have that number.

How are you testing your water?

 

[mileurjl]

LaMotte ColorQ Pro 7 is my tester of choice.

Before the first liquid Cl add, FC 0.09, TC 0.57, pH 7.2, ALY 69, CH 187, CYA 63. From the SWG discharge, FC and TC were 1.88 & 2.34.
After first 6.75 gals, FC & TC were equal at 2.53, pH 7.3, ALY 95.
Shortly after, FC & TC were down and spread >.5.

I'll pick up some more liquid and follow the SLAM procedure.

 

[BoDarville]

I've been floating Tri-chlor/Tri-azine tabs in an effort to supplement the IC40.

Continued use of these products could raise your CYA above the recommended level and increase the amount of FC needed to maintain proper sanitation. Your current CYA numbers are fine for an SWG...just keep an eye on your CYA if you continue supplementing using Trichlor.

I also use Algimycin 2000 and Sea Klear Problem Klear for algae control.

You can save some money as neither of these products are necessary for algae control. Proper chlorination will provide you with all the algae control you will ever need.

After first 6.75 gals, FC & TC were equal at 2.53

This is not nearly enough chlorine to properly SLAM the pool. For your CYA, you need to maintain an FC of 24 ppm until you pass the criteria outlined in the SLAM process. Check out the Chlorine / CYA Chart which shows the amount of chlorine needed for proper SLAMming and ongoing sanitation. If your chlorine is being consumed as quickly as your results indicate, there is something organic alive in your pool even if your water appears clear. If your pool has a light, ladder, or removable steps, check in and around these fixtures for hidden algae.

 

[jblizzle]

Well, once you read the SLAM process you should quickly realize that your tester is not going to be adequate. It maxes out at a FC of 10ppm and you need to maintain significantly higher than that. Also search the forum for color q, it has been repeated found to be inadequate and inaccurate, especially for the important CYA level.