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Thread: Algae Wars

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    Firefly2000's Avatar
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    Algae Wars

    Great info on this site! Thanks to all contributors!

    I have a pool that's about 18 months old. For the last 9 months, I have been at war with blue/green algae and probably some black algae as well. The algae normally resides on the pool walls and floors and has clouded the water on 3 separate occasions (blooms). Brushing removes most of it, but I do get noticeable green stains on the blue pool surface.

    I have been through three different pool shops and been burnt by pool shop staff not know what they're talking about coupled with questionable results from their test equipment... Upon the advice of the pool shops we have tried shocking, algaecides, starver, brushing.... just about everything that everyone tells you to do. The problem is that the algae disappears for a short while and then quickly returns again.

    My chlorine levels have usually been somewhere between 3 and 6, and PH is always been around 7.5. The automated dosing system is working fine.

    I finally gave up on pool shop advice and decided to start educating myself. After reading through the information on the BBB method on this site, I think I've finally worked out why I've had such a major problem, and I thought I'd bounce my theory off you guys for comment...

    Around 9 months ago I changed pool shops as the original shop was now under new management. It was obvious that the new owner did not understand pool chemistry so I moved on. The new pool shop used a different testing method (strips) and insisted that there was no CYA in my pool, despite the fact that 1 week earlier CYA was around 30. So we added a significant quantity of CYA on two separate occasions (the test strips gave weird results on CYA). I recently moved on to a third pool shop (who also used the test strips, and their readings were 0 CYA!!! I took the same sample back to the first pool shop and CYA was now 100!)

    To cut a long story short I've recently had my water tested using a proper reliable test kit and CYA was in fact around 100.

    I'm now convinced that my CYA has been sitting around 100 for a couple of months now, and despite being winter, shocking & brushing, algae is still laughing at me!

    According to the Chlorine/CYA charts, because of the high CYA levels, my chlorine should be much higher than the 3-6 range that I've had it at... I can only conclude that the real problem has not been chlorine, phosphate or PH levels, but the high CYA levels!

    Am I correct?

    (I can't believe that the pool shops did not pick this up! I remember one pool shop telling me that it was a good thing to have high CYA - "the more the better"..)

    Do I start dumping water to resolve my problem? My theory is that I need to get CYA down to around 20-30 and then I can shock the pool and rid algae for ever!
    Daniel

    47000L (12500 gal)
    IG Quartzon Interior
    Rolachem Acid & Chlorine dosing
    Paramount In-floor cleaner
    1.5HP pump + Sand filter
    Solar heating under the great Aussie sun!

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    Butterfly's Avatar
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    Re: Algae Wars

    Yes, it does sound like your problem is high CYA; however, a full set of test results from a realiable source is always preferrerd.

    Lowering your CYA to a more managable level does not necessarily mean to take it below the recommended range. 30 to 50 is recommended if you use bleach ( 70 to 80 for a SWG).

    If your pool is in direct sun, you may even do better with a little higher CYA.
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    Mod Squad JohnT's Avatar
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    Re: Algae Wars

    Quote Originally Posted by Firefly2000
    According to the Chlorine/CYA charts, because of the high CYA levels, my chlorine should be much higher than the 3-6 range that I've had it at... I can only conclude that the real problem has not been chlorine, phosphate or PH levels, but the high CYA levels!

    Am I correct?

    (I can't believe that the pool shops did not pick this up! I remember one pool shop telling me that it was a good thing to have high CYA - "the more the better"..)

    Do I start dumping water to resolve my problem? My theory is that I need to get CYA down to around 20-30 and then I can shock the pool and rid algae for ever!
    I believe you are correct.

    Apparently your pool stores are as bad as ours.

    20-30 is probably too low. IMO, 40 is a good number to go for, but if I were in your situation I would go for about 70ppm to start with, then allow rainwater dilution etc. to lower it over time.

    One thing to be aware of is that many CYA tests are not accurate at high levels, so your 100ppm reading might really be higher than that. Often people will measure their water at 100ppm, drain half the water and find that the CYA is still 100ppm.
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    frustratedpoolmom's Avatar
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    Re: Algae Wars

    I feel your pain, sounds like almost identical to what I went thru with the pool stores, they know virtually nothing about the relationship between CYA and chlorine and algae.

    I agree with the above, try a partial drain and to get it lower, say 60 or 70 and then see what happens. I ran with 70 all last summer, shocked once and after that was able to maintain the FC at 8 or so and never had anymore problems. This year I was able to get it down to 40-50.

    Good luck!
    Helpful links: Pool School; CYA/Chlorine Chart
    24' round AG pool, 52" high, Raypak heater; Waterway 2 spd Pump;
    150 Sq ft. Clearwater Cartridge Filter; Former and DISSATISFIED "Pool Frog" owner
    http://www.PerfectlyClearPoolService.com

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    Re: Algae Wars

    I agree with the others. From everything I've read, with under 30 CYA you would be using up chlorine for no reason, getting it burned off quickly.
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    Re: Algae Wars

    Everyone has given great advice, all that is left to say is Welcome to TFP!

    8000 gallon 20' x 48" round vinyl frame pool, 12" sand filter (don't have the specs on the pump), TF100 test kit
    Handy Links: PoolMath, TF-100 Test Kit, Pool School, CYA-Chlorine Chart
    "Shock" is a process, not a product!

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    Firefly2000's Avatar
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    Re: Algae Wars

    Thanks everyone for your input. I'll start working on lowering my CYA.

    I would also like to add that I have a water feature in one corner of the pool that runs twice a day powered by the pool filter pump. Water gets pumped into a pot and trickles down the side of it into a small elevated shallow (8 inches deep) pond. Once the pond fills up it flows over a weir and into the pool (about another 8 inch drop into the pool).

    Would having such a water feature running every day contribute to any problems for me? Apart from the algae wars, I have also struggled with low TA (usually around 50-80).

    I've attached a picture of the water feature.

    Thanks
    Attached Images Attached Images
    Daniel

    47000L (12500 gal)
    IG Quartzon Interior
    Rolachem Acid & Chlorine dosing
    Paramount In-floor cleaner
    1.5HP pump + Sand filter
    Solar heating under the great Aussie sun!

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    frustratedpoolmom's Avatar
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    Re: Algae Wars

    Actually, having your TA in that range will help keep your PH in range. If your TA was over 100 or so, your water feature could actually cause a PH rise.

    That's a neat feature...never seen anything like it.

    When do we see the REST of the pool??????
    Helpful links: Pool School; CYA/Chlorine Chart
    24' round AG pool, 52" high, Raypak heater; Waterway 2 spd Pump;
    150 Sq ft. Clearwater Cartridge Filter; Former and DISSATISFIED "Pool Frog" owner
    http://www.PerfectlyClearPoolService.com

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    Firefly2000's Avatar
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    Re: Algae Wars

    Ok. Here's the rest of the pool. We have stepping stones alongside the house as an added feature and also for access.

    Pavers are all Australian Limestone. Photos are about 12 months old. The fences are now almost covered up by the plants.
    Attached Images Attached Images
    Daniel

    47000L (12500 gal)
    IG Quartzon Interior
    Rolachem Acid & Chlorine dosing
    Paramount In-floor cleaner
    1.5HP pump + Sand filter
    Solar heating under the great Aussie sun!

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    Re: Algae Wars

    LOVE the stepping stones!!!
    What a clever idea.
    12500 AGP 2HP Sand filter
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    frustratedpoolmom's Avatar
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    Re: Algae Wars

    The stepping stones are cool. I also like the clear fence, really keeps the area open and spacious looking. Very nice! Sean should put it in the slide show.
    Helpful links: Pool School; CYA/Chlorine Chart
    24' round AG pool, 52" high, Raypak heater; Waterway 2 spd Pump;
    150 Sq ft. Clearwater Cartridge Filter; Former and DISSATISFIED "Pool Frog" owner
    http://www.PerfectlyClearPoolService.com

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    Re: Algae Wars

    Man, that is nice! Love the stepping stones and the water feature!
    Hey, check out the Pool School section from the home page, TA is pretty easy to bring up if you need to...you may have seen it already but if not it's in some of the basic chemistry posts.
    Todd
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    Re: Algae Wars

    Those stepping stones look pretty cool. That certainly would not be permitted here in the states. Most places have some rules about how close the waters edge can be from the house. 5' is fairly typical.

    I hope that glass is tempered. It looks like it is from the picture.

    Boy I miss Australia. I've been to Sydney and Cairns twice.
    11000 Gals, Intelliflo, Sta-Rite Cartridge, Polaris 360

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    Firefly2000's Avatar
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    Re: Algae Wars

    We actually had to modify the foundations of the house to be able to build the pool that close to the house. We had to underpin the corners of the bay window with 600mm (2' deep) peers to take the load of the house to a point below the excavation of the step stone area. So, from a structural perspective this can actually be done successfully, and I would be surprised if local authorities in the US would not allow this...

    The glass is what we call "safety" glass or "toughened" glass here in Australia. It's 12mm thick (just under 0.5 inches) and is very difficult to break. With pool fencing absolutely mandatory here, glass is becoming more popular, although it is rather expensive.
    Daniel

    47000L (12500 gal)
    IG Quartzon Interior
    Rolachem Acid & Chlorine dosing
    Paramount In-floor cleaner
    1.5HP pump + Sand filter
    Solar heating under the great Aussie sun!

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    Firefly2000's Avatar
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    Re: Algae Wars

    Six weeks since my first post, pool has been crystal clear for about 4 weeks now. My CYA levels are now around 40-50 and the algae is staying away!

    This is a BIG win for me after months of frustration! Thanks all for you help.

    I still have some green stains on the walls in places. There are also some darkish (green/brown) patches in the bottom of the pool (particularly in the shady areas). Brushing does not appear to have much affect. At the moment it's not getting any worse, and it might even be fading. I'm hoping that it's just ingrained algae (hopefully dead) that will eventually go away with correct FC and brushing every now and then....

    Any thoughts?
    Daniel

    47000L (12500 gal)
    IG Quartzon Interior
    Rolachem Acid & Chlorine dosing
    Paramount In-floor cleaner
    1.5HP pump + Sand filter
    Solar heating under the great Aussie sun!

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    Re: Algae Wars

    I had some stains on my pool that I thought wouldn't go away. but with constant contact with the chlorine in the water they slowly disappeared.

    Very nice pool design. I can see with the small yard why you would go to the extra effort to strengthen the foundation to get it closer to the house. Otherwise you wouldn't have more then a rectangular lap pool. Great job.
    18' AG Vinyl Pool (7,500 gal)
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    Re: Algae Wars

    Keep your FC up a little higher than called for and the stains will slowly fade away. Not always, but very, very, likely. It may take a couple of weeks or more but they'll disappear.
    Dave S. - Forum owner
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    Firefly2000's Avatar
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    Re: Algae Wars

    Thanks for the replies. I forgot to mention in my previous post that I followed the advice on this forum... TF100, shock, brushing etc... I've done so much reading here lately. To those of you that are new around here, read, read, read and follow advice. I'm now looking forward to a (hopefully) trouble free pool season, which should start around the end of September for me!

    I'm currently running FC at around 8-10, with CYA at around 45-50. All other numbers are good.

    Duraleigh, should this FC level be high enough for these stains to theoretically disappear after say a month or so?

    It's still winter over here and the sun is still fairly low in the sky. Only about 2/3 of the pool gets sunshine, so it's not hard to keep the FC levels high.
    Daniel

    47000L (12500 gal)
    IG Quartzon Interior
    Rolachem Acid & Chlorine dosing
    Paramount In-floor cleaner
    1.5HP pump + Sand filter
    Solar heating under the great Aussie sun!

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    Re: Algae Wars

    Duraleigh, should this FC level be high enough for these stains to theoretically disappear after say a month or so?
    Yes, I'd say that's very reasonable. If they aren't gone or greatly diminished after a month, then it's most likely not an organic stain. My bet is they will be gone.........maybe even a little sooner if you keep your FC up there where it is now....then you can let it drift back down to 3-5 or so for the rest of the summer.
    Dave S. - Forum owner
    42k vinyl and concrete pool, 1.5hp pump, 140gpm filter
    TFTestkits , PoolMath , Pool School

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    frustratedpoolmom's Avatar
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    Re: Algae Wars

    I had tea-colored stains for several years, running with a higher FC and finally they are faded to the point where only I can see them, LOL, and most of the time even I can't. I would say a few months at the higher FC and they should fade rather well. Glad to hear your good news!
    Helpful links: Pool School; CYA/Chlorine Chart
    24' round AG pool, 52" high, Raypak heater; Waterway 2 spd Pump;
    150 Sq ft. Clearwater Cartridge Filter; Former and DISSATISFIED "Pool Frog" owner
    http://www.PerfectlyClearPoolService.com

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