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Thread: Newbie scrambling to deal w/ algae, high CYA and well water/iron before winter close

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    Newbie scrambling to deal w/ algae, high CYA and well water/iron before winter close

    Hi! My wife and I bought a house last month that came with an appx 30,000 gal 20x40 plaster in-ground pool with a sand filter. The prior owner had recently shocked and FC was still at about 10 ppm when we moved in, which seemed high, so I stopped adding chlorine and let it drop down to around 2-3 ppm (this took awhile since the pool had a solar cover on it and we weren't using it much). Unbeknownst to me the pools CYA was in the 160-170 range (prior owner used chlorine pucks), which now that I've discovered this site I understand means I should have left the chlorine levels where they were (or higher). Combined with storms/leaves in the pool last week, long story short I got my first algae bloom a few days ago.

    Came to this sight (having discovered it a few weeks ago) and read about the procedure for slamming the pool. Broke out the test kit I had ordered a couple weeks back and realized the high CYA was probably where I went wrong and would also mean that slamming the pool would require a huge amount of chlorine unless I could lower CYA. To lower CYA I drained and refilled about 70% of the pool. Fill water came from our well. As I was refilling (took a couple days), I was adding bleach to raise to shock levels (trying to hit something of a moving FC target as the pool refilled). Been at shock levels for about two days now.

    This is where I'm currently at:

    FC: 25
    CYA: 55
    Ph: 7.2 (I believe...can't reliably test anymore due to high chlorine, but the pool water was 7.2 and the fill water measures 7.2 also)
    TA: 180
    CH: 600

    Water seems to have cleared a little bit (can now faintly see the drain at bottom of deep end) but still pretty green. Also, while adding water there was a decent bit of brown sediment settling at the bottom of the pool (iron from well water?). It seems to have dispersed some from running the filter but I can still see sort of a haze of brown dust collected along the walls in the deep end. Filter and polaris have been running for about 48 hours (without skimmers because water is still below the skimmer line).

    Right now I'm kind of at a loss what to do next. Was scheduled to have someone come close the pool today but this development obviously threw a wrench into things. When the pool guy came out this morning he said the algae should already be dead from the chlorine and that the iron from the well water appears to have oxidized (turned brown) from the chlorine and to just turn off the filter and let the sediment collect at the bottom and then he'd come back tomorrow, sweep, and then close the pool. I'm a bit nervous about closing the pool the way it is without clearing the water first, dealing with whatever the well water may have introduced to the water, etc, etc, and feel like maybe I should delay another week but at the moment the plan is for him to come tomorrow morning to close unless I tell him otherwise. I feel like I'm asking for trouble next spring if I close the pool as it is...Am I being paranoid?

    Any advice would be much appreciated, and thanks in advance!

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    smforte's Avatar
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    Re: Newbie scrambling to deal w/ algae, high CYA and well water/iron before winter cl

    Personally, I'd wait. Get it cleared before closing. Keep your eye on iron staining due to well water. The sediment may be dead algae. Keep slamming until you pass TFP 3 test. Good luck!
    Montgomery, AL
    27000 16 x 36 IG, Vinyl, Grecian, Hayward Sand filter, 1 HP Pentair whisperflo motor, Aqua Genie filter not by choice, no extra jets, Dolphin s300i robotic cleaner,Taylor K 2006 test kit, speed-stir which I couldn't live without!

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    Re: Newbie scrambling to deal w/ algae, high CYA and well water/iron before winter cl

    How are you vacuuming? Auto-vac? Is your pump running 24/7? Have you backwashed?
    Dave S.
    42k vinyl and concrete pool, 1.5hp pump, 140gpm filter
    TFTestkits , PoolMath , Pool School

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    Re: Newbie scrambling to deal w/ algae, high CYA and well water/iron before winter cl

    Quote Originally Posted by smforte View Post
    Personally, I'd wait. Get it cleared before closing. Keep your eye on iron staining due to well water. The sediment may be dead algae. Keep slamming until you pass TFP 3 test. Good luck!
    Took that advice and happy to report that the pool is pretty much clear as of this morning. Added a bit of DE to the sand filter yesterday and I think that sped things up quite a bit. Not sure if the green I was getting was from algae or from metal in the well water fill, but either way it seems to be gone now. When backwashing the filter the glass bubble on the filter turned a deep reddish brown and took awhile to clear, so I'm guessing there was a fair bit of rusty sediment pulled out of the water.

    Only concern now is that the filter, which normally operates at about 21psi, seems to be stuck at 25psi even after backwashing. Not sure if maybe I screwed something up adding the DE. I added more (almost 4 cups) than what is supposedly typical (1-2 cups), but the filter pressure only raised about 1/2 psi total (rather than the 1 psi recommend) before I got nervous and decided to stop adding anymore.

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    Re: Newbie scrambling to deal w/ algae, high CYA and well water/iron before winter cl

    Quote Originally Posted by duraleigh View Post
    How are you vacuuming? Auto-vac? Is your pump running 24/7? Have you backwashed?
    I have a Polaris vac running off a booster pump, and was filtering 24/7. The filter psi never really moved much (maybe .5 psi) even though I was catching a bunch of brown sediment, which was apparent when backwashing (which I was doing daily even though the pump pressure was pretty stable). Then as suggested above, after adding the DE to the filter the pool really started to clear pretty quickly and the pump pressure rose to about 25psi, and now seems stuck there even after backwashing.

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    Re: Newbie scrambling to deal w/ algae, high CYA and well water/iron before winter cl

    You should consider deep washing your filter. Look for the post describing the procedure.
    South of France inground rectangular 17k pool - ruber membrane. Sliding dome, black thermal blanket covering 75% of the pool surface. Aqualux 3/4Hp pump, glass media sand filter, Zodillac robot, 110W UV-c lamp, Hayward brominator, Caliente 12kW heat pump.

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    Re: Newbie scrambling to deal w/ algae, high CYA and well water/iron before winter cl

    Quote Originally Posted by Tepelus View Post
    You should consider deep washing your filter. Look for the post describing the procedure.
    Thanks...I'll give that a try.

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    Mod Squad jblizzle's Avatar
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    Re: Newbie scrambling to deal w/ algae, high CYA and well water/iron before winter cl

    Please add your pool details to your signature as described HERE as it will help us help you.

    FYI: Deep Cleaning your Sand Filter
    Jason, TFP Moderator
    18k IG pebblesheen pool, Hayward ProLogic P4 w/ T-15 SWG, Pentair 1HP 2-speed Superflo, Hayward 6020 DE filter
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