Solar Cover and Algae.....again

Hi all, I posted awhile back about what appeared to be a problem with algae when the solar cover is left on. The suggestions here were that the algae that I had prior to leaving the cover on for several days probably wasn't dead. So, with a CYA of 40, I raised the FC level to between 10 and 15 and left it there for 8 days. No combined chlorine, let the FC settle to 5 so the kids could swim. Now, it turned cold here in Atlanta, and windy so a few leaves, etc got in the pool. I put the solar cover on while the cool rainy weather was here. It lasted for better than a week, maybe 10 days, cover on all the while. I still ran the pump and checked CL. One day after a particular rain, I checked and CL was less than 3, so I added bleach to bring it to 5. Two days later, it's getting nice out again, I take the cover off to clean leaves off the bottom, and lo and behold, algae is starting to appear. It's fairly shaded by trees there, I'm thinking that may have something to do with it. What next? The water was fairly clear, just starting to get algae on the walls. Should I use some Polyquat? What about Phos-free?

I would not add phos-free. Polyquat (60%) won't hurt if you want to use it. My advice is to go ahead and shock the pool back up again. You said that you brought cl up to 5, then it was two days later and your pool has algae beginning. Your cl level might have dropped down to low. With cya of 40, you shouldn't let it drop below 3. Since yours did, you may have had some algae starting to grow at that point that you just didn't see and thus bringing it back up to 5 wasn't enough to kill it. And, the 5 may have quickly been consumed killing the stuff that was beginning to grow, so your cl may actually have been next to nothing during those two days. At any rate, shock it and keep it at shock level for a few days.

Quote:

---

Originally Posted by Watermom

I would not add phos-free. Polyquat (60%) won't hurt if you want to use it. My advice is to go ahead and shock the pool back up again. You said that you brought cl up to 5, then it was two days later and your pool has algae beginning. Your cl level might have dropped down to low. With cya of 40, you shouldn't let it drop below 3. Since yours did, you may have had some algae starting to grow at that point that you just didn't see and thus bringing it back up to 5 wasn't enough to kill it. And, the 5 may have quickly been consumed killing the stuff that was beginning to grow, so your cl may actually have been next to nothing during those two days. At any rate, shock it and keep it at shock level for a few days.

---

Thanks, that's what I figured. I added some polyquat last night, and added enough bleach to bring the cl back up to 10, do you think I should shoot for 15? What's wrong with Phos-free? Is it just a rip off, or do pools not get high rates of phosphates?

You can try 10, but if you don't see progress, bump it up to 15. Or just go on up to 15. With cya of 40, that would be fine. But the key here is to sustain the high reading. Don't let it yo-yo up and down. I don't know too much about phos-free, but the general consensus around here is that for most pools, you don't need to worry about phosphates.

Quote:

---

Originally Posted by Watermom

You can try 10, but if you don't see progress, bump it up to 15. Or just go on up to 15. With cya of 40, that would be fine. But the key here is to sustain the high reading. Don't let it yo-yo up and down. I don't know too much about phos-free, but the general consensus around here is that for most pools, you don't need to worry about phosphates.

---

Thanks. I'm going to keep it at 15......again! I just can't for the life of me figure out that after keeping it close to 15 for a week, brushing backwashing, etc that after having the solar cover on for a week it started getting algae on the walls. The water was still clear, so I guess I caught it early.

Make sure you are removing all the leaves and debris, as this will use up Cl big time. Check skimmer, and pump basket as well.

Pat