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Thread: Algae back less than a week post SLAM

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    Algae back less than a week post SLAM

    Well I thought I had all this TFP stuff figured out, but I am currently 6 days post SLAM and found several areas with green algae on the wall in the deep end .

    Obviously I need to SLAM again, but I'm not sure what happened. I have been checking my levels every day or two and FC has never dropped below 4.5. My CYA is 40 so that means my minimum FC is 3. Also my pump has been running 24/7 since the last SLAM because I haven't gotten around to re-attaching the on/off things to my timer.

    What did I do wrong?
    11,500 Gal Fiberglass IG Pool. Hayward cartridge filter with Pentair 3/4 HP pump
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    Re: Algae back less than a week post SLAM

    I'm going to first guess circulation. Do you have the ability to change your returns direction? Like, eyeballs?
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    Re: Algae back less than a week post SLAM

    What did I do wrong?
    Can't tell but you must always have firmly implanted in your pool management skills that algae will not grow in a pool with adequate chlorine.

    Of course "adequate" is the answer. Your algae is like everyone else's and chlorine kills it. Somehow you are not getting adequate chlorine to your or you are not keeping it there.
    Dave S.
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    Re: Algae back less than a week post SLAM

    Yes I can move the eyeballs on the returns. Which way should they be pointing? My pool has two returns, one on either side of the steps in the shallow end. The skimmer is in the corner on the deep end. There is also a main drain next to the wall in the deep end.

    This picture is from when I drained the pool, but it shows where the returns are


    Here you can see the skimmer location


    This one was taken near the end of the SLAM, but it shows the main drain location

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    Re: Algae back less than a week post SLAM

    It's also possible (I'll let others debate the likelihood) that you have a chlorine resistant algae like mustard algae that can grow even at recommended FC levels. I went through something similar, even after fixing my circulation issues (missing return eyeball) and passing the OCLT, the algae would still reappear on wall surfaces while FC was still above recommended levels. Very frustrating, indeed.

    If you must SLAM again, brush, brush, brush. Make sure you get everything. You could even consider doing 24 hours at mustard shock level after completing the regular slam.
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    Re: Algae back less than a week post SLAM

    I would go for a counter clockwise circulation in your pool.
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    Re: Algae back less than a week post SLAM

    It's also possible (I'll let others debate the likelihood) that you have a chlorine resistant algae like mustard algae that can grow even at recommended FC levels.
    That's quite true, some species of algae require more chlorine, no doubt.

    But the important thing to take away is that inadequate chlorine is the cause for algae. We may have missed what adequate was supposed to be but let's don't go back and debate the inadequacy.

    I hope TFPr's will recognize that the answer to eradicating algae in your pool still remains chlorine. The TFP charts and guides have all been developed using a ton of anecdotal information and a lot of science but no two pools will be exactly the same.

    In short the root cause for algae in the pool is lack of chlorine.
    Dave S.
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    Re: Algae back less than a week post SLAM

    Do you have a solar cover?

    Do you brush weekly?

    How much chlorine are you adding?
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    Re: Algae back less than a week post SLAM

    Quote Originally Posted by ping View Post
    Do you have a solar cover? No

    Do you brush weekly? Yes, the last time I brushed was a few days ago. As a mentioned in my first post it has only been 6 days since I completed a SLAM, so I was brushing everyday during that process.

    How much chlorine are you adding? About 3 cups of 10% liquid chlorine per day. I am using 7 FC as a target and the pool is consuming 2-2.5 FC per day.
    I do get a decent amount of leaves/plant debris that fall into the pool too, but I try to skim every day and it doesn't generally get too bad on the bottom before I have time to vacuum it out (generally once a week). I occasionally use a suction cleaner, but it plugs in to the skimmer, and takes a long time to get everything off the bottom. If I leave it in all day, there are generally more leaves on the surface than what was originally on the bottom so it doesn't seem worth it to use it very often. Manually vacuuming is more effective.
    11,500 Gal Fiberglass IG Pool. Hayward cartridge filter with Pentair 3/4 HP pump
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    Re: Algae back less than a week post SLAM

    Ok, I adjusted the returns a bit to attempt clockwise circulation and officially started the SLAM this morning.

    FC: 17 (target was 16)
    CC: 0.5
    pH: should be 7.2 (it tested at 7.7 this morning so i added muriatic acid but did not retest before adding chlorine)
    CYA: 40 (from last week - I will retest to verify the next time we get some sun)
    11,500 Gal Fiberglass IG Pool. Hayward cartridge filter with Pentair 3/4 HP pump
    500 Gal Fiberglass AG Spa with cartridge filter
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    Re: Algae back less than a week post SLAM

    Sometimes algae is hiding in small niches like behind the light. Any chance you can take that out and scrub the niche out?
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    Re: Algae back less than a week post SLAM

    The light has been out of the niche for the past few weeks. I've been brushing in there when I brush the walls, but you have a good point, I should probably get in the water before this SLAM is done to thoroughly scrub it with a smaller brush.

    The water is still a bit cold for me (70-72) but I'll try to convince my husband to do it or just suck it up and do it myself. I'd rather be cold for a few minutes than have to keep dealing with algae. Plus, I need to measure the main drain so I can get the right size cover for it. I also want to verify that there is actually suction through the main drain. I havent been in the water yet (we bought the house this past November) so it's more of a sanity check than anything else.

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    Re: Algae back less than a week post SLAM

    Well, we both went swimming this weekend and scrubbed the light niche while we were in there. We also verified that the main drain does in fact have suction. It feels like it's 50/50 with the skimmer, which is what I expected since there are no valves to adjust and only 1 pipe entering the pump.

    I also passed the OCLT last night and CC has been 0.5 or below the whole time. The water is still crystal clear, but either my mind is playing tricks on me or there was a hint of green on the wall in the deep end when I was brushing this morning. I think I'll pay it safe and keep SLAMing.
    11,500 Gal Fiberglass IG Pool. Hayward cartridge filter with Pentair 3/4 HP pump
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    Re: Algae back less than a week post SLAM

    I personally like the idea of brushing with a smaller brush around returns and such. I've found algae behind my returns and in the cracks where my steps meet the vinyl in my pool. I also found a bunch caked up just inside my skimmer box in the corner.
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    Re: Algae back less than a week post SLAM

    Good idea Aimee, I brushed the skimmer when i was swimming Saturday, but how do you remove the returns? Do they just unscrew?
    11,500 Gal Fiberglass IG Pool. Hayward cartridge filter with Pentair 3/4 HP pump
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    Re: Algae back less than a week post SLAM

    I finished my SLAM, raised FC to mustard shock level for 2 days and scrubbed everything I could reach. I still haven't removed the returns to clean behind them since I think I need a special tool that I don't own yet.

    I finished the mustard SLAM 6/1 and then let my FC drift back down. FC has not dipped below 5 (my minimum per pool math is 3 for a CYA of 40).

    It is now 6 days later and I noticed some algae on the deep end wall again this is getting really frustrating. How do I get rid of this stuff? I feel like I'm following all the guidelines on this site but it's not working. Should I just maintain elevated FC (above normal target, but below SLAM) for a long time?
    11,500 Gal Fiberglass IG Pool. Hayward cartridge filter with Pentair 3/4 HP pump
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    Re: Algae back less than a week post SLAM

    Your spa isn't connected to your pool is it?

    How is the circulation? How many returns and skimmers do you have? Can you point your returns in different directions (eyeballs)?
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    Re: Algae back less than a week post SLAM

    with your returns over 20 feet away from the suction, and only a 3/4 hp pump, I'm still betting circulation is your problem. Have you ever taken a FC reading from down by the algae, and compared it to a test from the shallow end?
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    Re: Algae back less than a week post SLAM

    No, my pool and spa are not connected. I havent had any issues with the spa.

    I have not tried testing FC from the two ends of the pool and comparing. I will do that when I get home tonight. I usually pull my water sample from half way between the two.

    If it is a circulation issue, what can I do about it? Does it just mean I have to brush every couple days to keep the water stirred up better? My returns are currently set to attempt counterclockwise water rotation (one is diagonal across the shallow end and the other is down towards the deep end). Should I point both towards the deep end? My pump is still running 24/7 at the moment so with my existing equipment I'm not sure how else I can increase circulation.

    Also, I'm not sure if it matters for this issue, but I get noticibly more suction from the skimmer than the main drain. They are tired together under ground so it should be 50/50 (there is only one hole in the bottom of the skimmer and one pipe coming out of the ground into the pump. I am fairly certain there is a clog in the main drain since I played with it this past weekend and the pump loses prime and the filter losses pressure when I put a rock over the skimmer drain.
    11,500 Gal Fiberglass IG Pool. Hayward cartridge filter with Pentair 3/4 HP pump
    500 Gal Fiberglass AG Spa with cartridge filter
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    Re: Algae back less than a week post SLAM

    Also, I'm not sure if it matters for this issue, but I get noticibly more suction from the skimmer than the main drain. They are tired together under ground so it should be 50/50 (there is only one hole in the bottom of the skimmer and one pipe coming out of the ground into the pump. I am fairly certain there is a clog in the main drain since I played with it this past weekend and the pump loses prime and the filter losses pressure when I put a rock over the skimmer drain.
    You need this device...Skimmer equalizer.jpg
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