I Think I Need to SLAM Again!

[hellstorm2004]

Hello All,

I think i need to SLAM my pool, the chlorine in the water just wouldn't stay. Poured three gallons yesterday. And now its down to 0.5. In just over 28 hours. And this time i think its mustard algae. I blame the recent duck infestation, i think they pooped on my pool and made it full of bad stuff. Also a mama duck has laid eggs just beside the pool. I will do an overnight FC loss test, i just poured two more gallons and will test it out later tonight. And check in the morning.

Chlorine/CYA Chart

But i couldn't make sense of the two columns, Yel/Mstrd Min and Yel/Mstrd Shock. What is difference between the two?


I guess its time to looks for bleach coupons!

 

[Texas Splash]

I wouldn't worry about that link right now. The treatment for suspected MA is the same as a regular SLAM (link below). So whatever your CYA is, raise your FC to that applicable SLAM level for now. Continue on the normal SLAM until you pass the 3 SLAM criteria. Once you pass, THEN look at the Poolmath calculator (link below) and down at the bottom is a number for MA treatment. Use that number, and only go that high for 24 hours. That's how we treat true MA. Hope that helps.
Pool School - Mustard Algae

 

[hellstorm2004]

Ah! That helps. My current CYA is 50. So i guess, lots of bleach to buy!!

Well my pool passes the first step even now. I have 0 CC!

 

[hellstorm2004]

Hmm... The overnight test went well. Tested at 01:00 last night and tested at 08:45, an FC loss of only 0.5. And CC is at 0.5. Baffled really!


Is it the sun that is eating out the chlorine?

 

[Texas Splash]

Bleach only goes to two places - algae and the sun. If your testing was correct, your OCLT was good, so that leaves the sun. A CYA of 50 is fairly strong, but I have mine at the 60-70 range this time of year with our TX sun. So if you're comfortable with your OCLT results, then your next logical step would be to increase CYA a bit. Maybe 10 ppm at a time to see how well that holds. As long as algae is ruled-out, which it appears to be from your testing, then that leaves the sun as your main culprit and increasing CYA would be next. Hope that helps.