A Few Questions

[cpeterson70]

Was just thinking about testing pool water and had a few questions:

What makes algae grow? Is it not keeping CYA/Chlorine balanced?

Do you do an OCLT every night, once a week, when you feel like it?

If you fail an OCLT on one night, do you SLAM that day?

 

[Texas Splash]

Algae grows when there is an ideal combination of food (i.e. phosphates), water temperature, and light to support its activity. Pools that are neglected long enough to allow the FC level to drop too low for the current CYA may not have adequate protection to prevent algae. No, we do not perform an OCLT every night, once a week, etc. Only when required to rule-out the need to perform a SLAM or ensure the SLAM is complete. Last time I did an OCLT was about a year ago. If we fail an OCLT, the typical response is to begin a SLAM immediately and continue doing so until al 3 SLAM criteria are passed.
Pool School - Defeating Algae
Pool School - SLAM - Shock Level And Maintain

Hope that helps.

 

[cpeterson70]

Thank you.

What would make you think to do an OCLT if one isn't performed regularly?

I just finished a SLAM about a week or so ago, so I was just curious what I should be looking for in my testing. I'm new to all of this and I'm a bit paranoid now...don't want to do that again!!

 

[Jezza]

If your battling to hold FC despite regular additions of chlorine and your water looks dull or cloudy-in the absence of any obvious algae.

 

[Texas Splash]

^^ Correct. There's no need to do an OCLT unless you need to rule-out any possibility of algae. If you see any hazy/cloudy water, you may need to do an OCLT. Another example, people often ask if they can raise the CYA a little more for the summer heat. I'll say okay as long as they are absolutely sure they are algae-free so that they know the FC loss is normal (2-4 ppm per day) and not due to excess organics.

After your SLAM your water should've been very clear, so if it ever changes from that clarity, you may need to do an OCLT.

 

[Chrissykr]

Sunday night I noticed my pool looked off. Everyone said I was crazy it was crystal clear.

I immediately decided to leave the pump running all night and perform an OCLT. I failed the OCLT, so Monday (a holiday naturally) I kept chlorine at 10 all day so everyone could swim. As soon as the last swimmer was out I brought it up to SLAM and brushed the entire pool at 11:00 at night. I lost 3.5 ppm Monday night. Yesterday I kept at it all day, brushing, testing adding chlorine. By last night I had my sparkle back. I passed my OCLT last night.

You will learn your pool and what it should look like.

In my case I know my robot does a crummy job in my deep end and yet I have let brushing go for a couple of weeks and the fertilizer guy came Thursday and I always run the robot after he leaves and I didn't this time. My CYA is 40 and my chlorine never went below 3.5 but I still got something brewing.

 

[cpeterson70]

Thanks for the replies. Very helpful!