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Thread: From low to high CYA, algae, now what?

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    From low to high CYA, algae, now what?

    I have read pool school and would love some clarification of a couple of things. I started this season with zero CYA and added approximately 3-4 pounds via sock over a three week period. Tested with my Taylor kit a couple weeks ago and it was less than 30. Tested today (as I am noticing algae in the pool) and it was 80. I have been using both liquid 12.5% chlorine and the pucks via a floating dispenser. I understand that now that my CYA levels are so high I would need a much higher FC level and that is why I am getting algae. My questions are:

    1. How, exactly, do I lower the CYA levels? I understand I will need to drain some water, but what is he best procedure for doing this?

    2. Should I just stop using the pucks altogether once I get the CYA levels where they should be (would that be around 30?)? Just add liquid bleach and stabilizer as necessary?

    3. I have added 90oz of liquid 12.5 bleach this morning and am brushing off the algae from the liner. What should I do next? Start draining a couple feet of water and re adding?

    FC 1. (Before I added the shock)
    CC less than 0.5
    pH 7.6
    CYA. 80. Using my Taylor test kit

    Thanks for your help on resolving this ASAP. I was hoping I wouldn't add too much CYA, and it appears I managed to do just that. Sigh

    Kelly
    kelly
    24' AG Round, 14,500 gal, 1 year old
    1.5 HP Pentair Pump, Sand Filter

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    Re: From low to high CYA, algae, now what?

    1. The only way to lower CYA is to drain and replace water. The best way is to pump out the water from the pool and add new. Since you have an AG pool, you may have other options, I don't know because I've never owned an AG pool.

    2. Pucks are what are adding CYA to your pool. If you continue to use them, you will continue to have this issue.

    3. You need to go to Pool School and follow the SLAM process. I recommend not doing this until you have lowered CYA to 30-40.
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    Re: From low to high CYA, algae, now what?

    Thanks for the quick reply. Should I filter to waste to accomplish this? From other posts it appears that you can go below skimmer level, refill, retest, repeat until desired levels are achieved. Am I understanding this correctly? As a side note, how high can the FC levels be and still be safe to swim in? I have seen many different numbers on this.

    Thank you!
    kelly
    24' AG Round, 14,500 gal, 1 year old
    1.5 HP Pentair Pump, Sand Filter

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    Re: From low to high CYA, algae, now what?

    You can use your vacuum hose and just siphon the water out, or you can buy a submersible pump and some hose and pump it out. Unless you have a floor drain, you won't be able to use your pool pump and backwash it out.

    I just use my 1 1/2 pool vacuum hose and siphon the water. They have good water flow and I have a couple extra's so I have 2 or 3 hoses set up if I need to drain a lot, like off the winter cover or draining the hot tub.
    12500 gallons, 24 foot round above ground
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    Re: From low to high CYA, algae, now what?

    1) Drain and refill. For you, since you have an AG pool, you could siphon the water off. Submerge a hose completely in the pool, place your thumbs over both ends, pull one end of the hose out and then remove your thumbs. This may be slow but it does not require any electricity. Since you have an AG pool, you could drain and refill 50% and get your CYA to 40.

    2) Yes, stop using pucks once CYA levels are where they should be. Just add liquid bleach only. Stabiliser=CYA.
    2.5) The recommended way of adding stabiliser is to put the powdered CYA in an old sock and hang in front of a return. Liquid stabiliser isn't really worth the cost for the benefit of raising CYA immediately. Do not add stabiliser once it is where you want it to be. I'm half the planet away and thus unable to comment on whether CYA 40 is ideal for your climate.

    3) Drain and refill before adding bleach. If you're going to drain, there's no point adding bleach because you'd be draining away some of the bleach.

    4) As long as the pucks are kept dry, you can use them when you go for vacation. But you MUST ensure that your CYA is low enough for you to be able to use them.

    If you don't understand anything, please ask.

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    Re: From low to high CYA, algae, now what?

    It is safe to swim with FC up to slam levels per the CYA chart.

    yes, you can drain the water below the skimmer, but NOT by filtering to waste UNLESS you have a floor drain.
    12500 gallons, 24 foot round above ground
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    Re: From low to high CYA, algae, now what?

    You can use the waste setting to dump some water...and quickly at that! As far as going below the skimmer....do you have a main drain? If your pump is only pulling from the skimmer it would seem that trying to use the waste option will cause you to have to stop before you get below it or risk pump damage. (I have only minimal knowledge here)

    The other option is to just siphon the water out using either a garden hose or a vacuum hose. Put the hose in the pool and make sure it's filled with water then hold your hand over one side and drag it over and let gravity do the work.

    But first, use pool math to calculate how much you need to dump. Since you're going to have to SLAM (visible algae) it's probably best to aim for 30 cya. So put your current CYA 80 in the now box and 30 in the target box and see how much water it tells you to replace.

    I bet someone will beat me to this post. I'm typing slow today!

    As far as what FC level is safe, you are safe up to shock level for your cya. With 80 that's pretty high. Let me find that cya chart....

    *edit*

    aha! I knew they'd beat me to it!
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    Re: From low to high CYA, algae, now what?

    Quote Originally Posted by bioteacher View Post
    Thanks for the quick reply. Should I filter to waste to accomplish this? From other posts it appears that you can go below skimmer level, refill, retest, repeat until desired levels are achieved. Am I understanding this correctly? As a side note, how high can the FC levels be and still be safe to swim in? I have seen many different numbers on this.

    Thank you!
    For you, with an AG pool, you have the luxury of being able to drain more water - as long as you leave at least one foot of water in the pool.
    We say as long as you can see the bottom, FC up to SLAM (but not above) is safe to swim in.

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    Re: From low to high CYA, algae, now what?

    Thanks, everyone. I do have a floor drain which I am currently running to waste. Already near bottom of skimmer level. I think I will drain about a third and refill and see where we are at. What is the ideal CYA for the Midwest United States where we have hot, humid summers and close for the cold winters?
    kelly
    24' AG Round, 14,500 gal, 1 year old
    1.5 HP Pentair Pump, Sand Filter

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    Re: From low to high CYA, algae, now what?

    I would think 40-50 is a good level. One factor to keep in mind, is do you want lower CYA to slam with or do you just want to drain to your target CYA? Lower CYA equals lower slam levels and less chlorine, where as higher CYA would mean higher chlorine levels during your slam. Cost of water and how green your pool is can play a part in that decision.

    Looking at pool math, 1/3 drain and fill should take your down to about 55 CYA, and obviously half drain would take you to 40. If the cost of water is reasonable, you could aim for 40 CYA then have room to use your pucks if you go on vacation or trips, and still be within a reasonable CYA range
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    Re: From low to high CYA, algae, now what?

    I guess I would like a middle ground. I don't like the idea of maintaining high chlorine levels because of high CYA, but I don't want my FC level walking that fine line at very low CYA levels. Last summer, our first with the pool, I had a heck of a time maintaining FC levels, but that was using pucks in an inline chlorinator which I swear never worked. I am hoping just using liquid chlorine will have better results.
    kelly
    24' AG Round, 14,500 gal, 1 year old
    1.5 HP Pentair Pump, Sand Filter

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    Re: From low to high CYA, algae, now what?

    You will definitely have better results! It's all about regular testing and knowing what you're adding.
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    Re: From low to high CYA, algae, now what?

    I have a well, so water is cheap (although not without issues). I will go ahead and drain half, refill, test and SLAM. Thanks to everyone for their help.
    kelly
    24' AG Round, 14,500 gal, 1 year old
    1.5 HP Pentair Pump, Sand Filter

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    Re: From low to high CYA, algae, now what?

    Quote Originally Posted by bioteacher View Post
    I don't like the idea of maintaining high chlorine levels because of high CYA
    It sounds like even after learning about the FC/CYA relationship you are still concerned about about that big FC number. You have heard so many times and seen on every set of test strips that 3ppm is high and we want you to run at 6. This mentality is left over from pre-cya days. Look up some posts by chem geek where he talks about effective FC. 6ppm FC at 50ppm CYA is way LESS harsh than 3ppm FC and no CYA.
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    Re: From low to high CYA, algae, now what?



    Sounds like a plan! No more pucks for you!

    (Well, maybe if there's a vacation involved...)
    18' x 48" (42" water depth) Intex Metal Frame 6,700 Gallons
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