Green problem. Algae?

[GearHead36]

We (my wife and I) definitely have a problem. I'm just not sure whether it's algae or not. A few months ago, we bought a house with a pool that had been neglected for a few weeks. It was green and cloudy, but not near as bad as one neglected for months or years. THAT was definitely algae. We bought a TF-100 kit, and learned the ways of SLAM'ing. In about a week, we got it nice and blue, and sparkling clear. But over the last month or so, we've had a couple of outbreaks of green. Slight green. A haze, or maybe just a tinge of green, along with cloudiness. Algae, I assumed. The first time I didn't do a full SLAM. I just elevated the FC a bit (10 or so as I recall), and it got blue and clear again. This weekend, it went green and cloudy on us again. A couple of nights ago (after sunset) I started a SLAM. I started off by dropping the pH to 7.2, then hitting it with bleach to get an FC of 14 (as recommended by Pool Math). I must have overshot a little. When I checked FC a couple of hours later, it was 18. I guess I'm off a bit on my water volume. This morning before sunrise, I checked it again, and it was 18.5, It went UP 0.5 ppm. I'm guessing that there's a little variability in the testing. Maybe one test had a slightly different amount of water, or something. Anyway, would this suggest that we're battling something other than algae?

It also seems that there routinely greenish stuff on the bottom. When I brush it, I see greenish clouds form behind the brush. The more I brush it, the more the pool clouds up and turns green and hazy. But this green doesn't seem to consume FC. We're testing on a 2 hr interval right now, and we didn't see FC drop until after sunrise.

This morning, it looks a little better. Bluer, but still cloudy. Here's a log of my current SLAM activity:


9/7/15 6:30pm

FC:2.5
pH:7.6
CYA:35
Added ~1 qt muriatic acid


8:10pm

pH:7.2

Added 3 gallons of bleach.


10:10pm

FC:18


9/8/15 6:30pm

FC:18.5


9:00am

FC:17


11:00am

FC:16


2:55pm

FC:12

Added 1/2 gallon bleach


6:00pm

FC:14.5


8:10pm

FC:14.5


11:00pm

FC:14.5


9/16/15 6:30am

FC:14.0

FC isn't dropping as I'd expect with an algae bloom. What's going on?

 

[Texas Splash]

Nope, it's algae. Based on your description or cloudiness and green, it's algae. Problem is most likely that you haven't technically completed the SLAN via the Pool School - SLAM - Shock Level And Maintain. Maintaining the required FC level until you pass all 3 SLAM criteria is that final "knockout punch" required to ensure algae is gone. Remember, a SLAM doesn't take just one or two days. It can take a several days, a week, or in some other member's cases with REALLY bad pools, several weeks. But bleach (chlorine) is your sanitizer of choice, so stay with it.

We have the same filter, so make sure you rinse it out 1-2 times a day, continue to scrub/vacuum often, and make sure there's nothing in your water that can contribute to retaining algae (i.e. ladder, light, behind a light, toys, etc). Your FC will eventually drop - it has to. If not by algae, then the sun. But when it starts to kill the algae, you'll know it and your CC should increase a bit as well.

- - - Updated - - -

Also, you may wish to double-check your CYA reading. As it stands right now, I rounded up your original reading to 40 which means you need an FC of 16, 24/7 with pump also on 24/7. If your CYA is higher than that, you may need to maintain a higher FC as noted on the Pool School - Chlorine / CYA Chart. Always good to confirm since so much depends on the CYA.

 

[GearHead36]

Nope, it's algae. Based on your description or cloudiness and green, it's algae. Problem is most likely that you haven't technically completed the SLAN via the Pool School - SLAM - Shock Level And Maintain. Maintaining the required FC level until you pass all 3 SLAM criteria is that final "knockout punch" required to ensure algae is gone.

But we passed the 3 criteria. And even now, it appears that we're passing the OCLT.

Remember, a SLAM doesn't take just one or two days. It can take a several days, a week, or in some other member's cases with REALLY bad pools, several weeks. But bleach (chlorine) is your sanitizer of choice, so stay with it.

First time, it took us about a week. We didn't try to shortcut the process.

We have the same filter, so make sure you rinse it out 1-2 times a day, continue to scrub/vacuum often, and make sure there's nothing in your water that can contribute to retaining algae (i.e. ladder, light, behind a light, toys, etc).

Hmmm. Ok, then I need to clean out the filter. Haven't done that since installing a new one right after the SLAM we did. We also have a ladder. Should I remove it? The ladder could be my culprit. I never scrubbed it down during our first SLAM.

Your FC will eventually drop - it has to. If not by algae, then the sun. But when it starts to kill the algae, you'll know it and your CC should increase a bit as well.

- - - Updated - - -

Also, you may wish to double-check your CYA reading. As it stands right now, I rounded up your original reading to 40 which means you need an FC of 16, 24/7 with pump also on 24/7. If your CYA is higher than that, you may need to maintain a higher FC as noted on the Pool School - Chlorine / CYA Chart. Always good to confirm since so much depends on the CYA.

Pump's on 24/7 now. I've measured CYA at 35 several times now, so I was pretty confident going with that result.

I thought that I did a "full" suite of tests with my TF-100 kit, but I see that I don't have CC. Can I get an accurate CC measurement with FC levels this high?

Thanks for the reply.

 

[Texas Splash]

Oh yes. Definitely check your ladder. If you can, remove it and really inspect it. Some ladders come apart at each step which can trap algae. Do you have a pool light? If so, inspect that as well. Many pools with removable lights have algae trapped behind the fixture. Yes, even if FC is high during a SLAM you can still test the CC with the reagents. The directions should be on the TF-100 card. But remember you can have algae even with little or no cc showing yet. It just means the algae has not been consumed by the free chlorine and is not yet being processed for oxidation (trash chlorine).

One other variable that is a bit concerning to me after re-reading your posts is consistency with testing. I think you even noted a concern about it. Becoming standardized with your FC testing is important - especially when doing the OCLT since 1 or 2 drops can mean the different between pass or fail. Also, when I round-up your CYA to 40, that would require an FC of 16, so you'll want to ensure it stays there. Speaking of OLCT, please keep this little note handy when testing:

When performing the OLCT, remember that it must be done when the sun has dropped – no sunlight on the pool. About 8 hours total is recommended. Also, your FC level should be elevated more than normal. Starting (bedtime) FC could be close to your SLAM level, but no lower than 10. Anything less and you may not receive an accurate portrayal of FC loss (by percentage), even if it’s only 1 ppm.

That's very important, but often overlooked.

Everything you're describing points to algae. The cloudiness, the plumes of green when your brush. That's classic algae. I suspect when you clean your cartridge it may be totally green as well. Mine used to be. Just to make sure ... you haven't added any other chemicals to your water correct? Nothing from the pool store? No well water? Just regular (plain) bleach and acid correct? I would continue following the SLAM instructions to the "T". Don't let up. Continue to monitor your levels and what you added not only to stay at your SLAM FC, but to see if the Poolmath Calculator is validating your pool capacity after adding products. I hope I haven't overloaded you with info. Please follow-up if you have any questions.

 

[GearHead36]

Oh yes. Definitely check your ladder. If you can, remove it and really inspect it. Some ladders come apart at each step which can trap algae. Do you have a pool light? If so, inspect that as well. Many pools with removable lights have algae trapped behind the fixture.

We have a light, but it's not currently in the pool. The light housing is sitting on the side. It has a leak that I haven't fixed yet, so it stays out for now. When I took it out, I DID find algae in the recess, which I cleaned. However, that MAY have been at the end of our SLAM, after the FC dropped a bit. I didn't want to get in the pool with the FC at SLAM levels.

One other variable that is a bit concerning to me after re-reading your posts is consistency with testing. I think you even noted a concern about it. Becoming standardized with your FC testing is important - especially when doing the OCLT since 1 or 2 drops can mean the different between pass or fail.

I think that we have achieved consistency with our FC testing. The quick test (5 drops into the little container with matching color squares) is not accurate enough for me or my wife. So we stick with the drop test. I think that one mistake I made was with the min FC level. I must have misread something, because I thought that the min for my pool was 2.0. But when I plug my numbers back into Pool Math again, I get a min of 3.0. So maybe I let the FC drop too low for too long.

Also, when I round-up your CYA to 40, that would require an FC of 16, so you'll want to ensure it stays there.

Ok. Latest bleach addition, followed 2hrs later with a test, resulted in an FC of 20.5. Should be good for a while.

Speaking of OLCT, please keep this little note handy when testing:
That's very important, but often overlooked.

Wasn't aware that the OCLT test had to keep the FC stable at a level above 10.

Everything you're describing points to algae. The cloudiness, the plumes of green when your brush. That's classic algae. I suspect when you clean your cartridge it may be totally green as well. Mine used to be. Just to make sure ... you haven't added any other chemicals to your water correct? Nothing from the pool store? No well water? Just regular (plain) bleach and acid correct?

Correct. Bleach. Muriatic acid. A little bit of tap water when the level dropped too far from evaporation. And one "puck" when we went out of town one weekend.

I would continue following the SLAM instructions to the "T". Don't let up. Continue to monitor your levels and what you added not only to stay at your SLAM FC, but to see if the Poolmath Calculator is validating your pool capacity after adding products. I hope I haven't overloaded you with info. Please follow-up if you have any questions.

Thanks.