Algae - need a primer!

[KurtV]

1. You can run the chlorine up to shock level and hope for the best.

2. You can use tri-chlor or di-chlor in a chlorinator.

3. You can get a friend to stop by every other day and add a bottle or two of bleach.

I prefer to manage my CYA so that I can use option 2. That is, have the CYA below 40 ppm when I go on vacation so that use of tri-chlor doesn't take it too high while I'm gone. I'm not always that good so I then resort to option 3. College-aged kids of friends and neighbors work well for this if you don't have family nearby to help. They're always looking to pick up a couple of bucks and some of them are responsible enough to follow simple instructions.

[heymom1]

Kurt, I will probably have to go with option 1 this time. We have no nearby teenagers or college students - only friendly with the neighbors, not friends. My FIL can come by and check on the pool but he can't come every night to add bleach. The CYA is high, around 90, but doesn't that just mean that the chlorine will stay around too?

The kids were in the pool just now, and the CL is probably around 8-10, according to the scale on my little test kit. It's a darker shade of yellow than 6, but not orange or anything.

Ph is about 7.3
No hardness
Alkalinity 100 ppm

Thanks again for the help. You guys are wonderful. I can post a photo now that we have a digital camera.

[KurtV]

If the algae is gone by then and you're just going to be gone a week, you could just leave your pool at shock level (25 ppm) and then have your father-in-law come over on the third or fourth day and add three or four 4 gallons of bleach. Three gallons will increase your chlorine by about 6 ppm and four gallons will increase it by about 8 ppm. Even if the pool uses 3 ppm per day, you'll return to a pool with at least 10 or 12 ppm which is adequate for your level of CYA.

[heymom1]

Kurt, do you know anything about ozonators? I noticed mine isn't working - the UV light isn't on, and it's too coincidental that it would go out and now we get algae for the first time. I'm sure that the chlorine level was the main problem, but that ozonator does help. I don't think pool stores carry the UV lights so I guess I have to send for one from the company.

I think you said it was still safe to swim in a pool with a 25 ppm cl level?

[KurtV]

Kurt, do you know anything about ozonators? I noticed mine isn't working - the UV light isn't on, and it's too coincidental that it would go out and now we get algae for the first time. I'm sure that the chlorine level was the main problem, but that ozonator does help. I don't think pool stores carry the UV lights so I guess I have to send for one from the company.

I don't know anything about them except that the ones that are usually sold to homeowners are generally not very effective. And I know you don't need it. If it were me, I wouldn't bother replacing the lamp.

I think you said it was still safe to swim in a pool with a 25 ppm cl level?
No, your shock level is 25 ppm. Acording to the Best Guess Chart your minimum free chlorine level is 8 ppm and the maximum is 15 ppm. You should only swim when the free chlorine level is between those two numbers.

Is your water clearing?

[heymom1]

Yes, the water has been clear since the first shock. No sign of the algae returning, but I'm going to keep the CL level high and dump some more shock in before we leave town. The water has never been murky - just the yellow slime on the pool walls, and that was gone the next morning after the shock.

but we did have a funny incident yesterday afternoon.

Younger son comes running inside after checking the pool "Something is really wrong with the pool! There's a big green blotch in it!" Older son runs outside to check...He comes back in after a few minutes, with a smile on his face.

The light green pool umbrella had been blown into the pool and was sitting on the bottom.

[heymom1]

The algae returned while we were out of town. Since I had the filter cartridges cleaned before we left, I'm just going to have to battle it away step by step. Raised the cl level back up with some Zappit and now the algae isn't visible. I'm going to order a test kit today.

My FIL actually came by twice and if I'd known he was going to do that I'd have asked him to dump in some bleach! Next time...