Green Water

Algae problems in swimming pool water.
Green (cloudy) water or slimy pool walls.
Black algae. Mustard algae. Pink or white pool mold.
CKC

Green Water

Postby CKC » Thu 20 Sep, 2007 09:58

I have a 21,000 gallon above ground pool. I had an algae bloom last week and I have green water. I have made 3 trips to the pool place in which all 3 times I have been given algicide and 4 bags of shock, plus 1 trip they had me add stuff to adjust the alkalinity. After yesterdays trip to the pool store and adding the 3rd round of algicide, 4 more shocks, vacuming, refilling with water and Muriatic Acid they assured me I would wake up to Blue Cloudy water this morning, and then we would deal with cloudiness after that. Guess what? Water looks the same this morning, green and cloudy. You cannot see the bottom of the pool. They tested my water yesterday and here were the results before chemicals: CYA 60, TC 1.4, FC 1.4, pH 8, TA 118. My friends say I need to use Bleach and quit waisting my money on all this algicide. Any advise would be greatly appreciated. Thanks so much.


JEB

Re: Green Water

Postby JEB » Thu 20 Sep, 2007 14:20

CKC wrote:I have a 21,000 gallon above ground pool. I had an algae bloom last week and I have green water. I have made 3 trips to the pool place in which all 3 times I have been given algicide and 4 bags of shock, plus 1 trip they had me add stuff to adjust the alkalinity. After yesterdays trip to the pool store and adding the 3rd round of algicide, 4 more shocks, vacuming, refilling with water and Muriatic Acid they assured me I would wake up to Blue Cloudy water this morning, and then we would deal with cloudiness after that. Guess what? Water looks the same this morning, green and cloudy. You cannot see the bottom of the pool. They tested my water yesterday and here were the results before chemicals: CYA 60, TC 1.4, FC 1.4, pH 8, TA 118. My friends say I need to use Bleach and quit waisting my money on all this algicide. Any advise would be greatly appreciated. Thanks so much.



Your Total Alkanity needs to be about 80-120, TC need to be around 10-20ppm , FC needs to be 5-10ppm , Your PH needs to come down to 7.2 to 7.4 and your hardness needs to 250-400 range, You will need a good clairifier once you have gotten the water balanced , Alot of the chems work best with balanced water.Bleach is nothing more that an ultra weak shock, Based off of what I read I would start with 8 Lbs of shock . Read the bottles of chems you have and use the amounts for a new pool fill that should get things going in the right direction.
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Postby chem geek » Thu 20 Sep, 2007 16:16

The Total Chlorine (TC) and Free Chlorine (FC) should be the same since the difference is Combined Chlorine (CC) and you want that near zero.

With a Cyanuric Acid (CYA) level of 60 you will need to maintain a Free Chlorine (FC) level of a minimum of 4.5 ppm at all times so will have to target a higher FC level to allow for loss from sunlight each day. Either that or you will have to use a weekly PolyQuat 60 algaecide. You CAN keep away algae with chlorine alone, but need to maintain an FC level that is at least 7.5% of the CYA level at all times. Just remember that Trichlor and Dichlor both add to CYA so you don't want to use those as your CYA level is high enough already. You should use unscented bleach or chlorinating liquid though you could also use Cal-Hypo if you watch your Calcium Hardness (CH) levels as Cal-Hypo will increase CH.

For shocking the pool that has existing algae, it will take 40% of the CYA level or 24 ppm FC to clear the algae quickly though even 15 ppm FC will clear it, albeit more slowly, but this level of chlorine must be maintained until all the algae is gone since the chlorine will get used up quickly killing algae -- so you'll need to add more several times during the day, especially the first day. Obviously, you'll need a good test kit that can test high chlorine levels such as the Taylor K-2006 test kit that uses a FAS-DPD chlorine test.

Richard
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Postby mr_clean » Thu 20 Sep, 2007 16:20

I have a 21,000 gallon above ground pool. I had an algae bloom last week and I have green water. I have made 3 trips to the pool place in which all 3 times I have been given algicide and 4 bags of shock, plus 1 trip they had me add stuff to adjust the alkalinity. After yesterdays trip to the pool store and adding the 3rd round of algicide, 4 more shocks, vacuming, refilling with water and Muriatic Acid they assured me I would wake up to Blue Cloudy water this morning, and then we would deal with cloudiness after that. Guess what? Water looks the same this morning, green and cloudy. You cannot see the bottom of the pool. They tested my water yesterday and here were the results before chemicals: CYA 60, TC 1.4, FC 1.4, pH 8, TA 118. My friends say I need to use Bleach and quit waisting my money on all this algicide. Any advise would be greatly appreciated. Thanks so much.


Have you cleaned/backwashed the pool filter?
the first thing you want to do is clean/backwash it so it will catch everything.
Having you been running it non-stop?
Needs to run until algae is gone and water is clear.
Have you checked your chemical level 2-3 times a day so chlorine stays above 20ppm.
you only need to add enough shock to get you above 20ppm and then keep adding chlorine to help level stay above 20ppm.
You can start balancing the rest of pool chemicals once algae is gone and chlorine is back to it's normal range.
CKC

Postby CKC » Fri 21 Sep, 2007 11:23

You guys are great, this is awesome to have such a resource. Last night my I put 3 bottles of bleach in my pool, this morning I woke up to sprakling blue cloudy water. So what is my next step??? I have been backwashing and vacuming to waste since adding all this stuff to kill the algae. So now how do we cure the cloudy??? Thanks so much!!!
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Postby chem geek » Fri 21 Sep, 2007 12:15

Maintain the high FC level (20 ppm or so) until all of the following three things occur:

1) the water is crystal clear -- no visible signs of algae or cloudiness or even dullness
2) you measure minimal (<= 1 ppm) overnight Free Chlorine (FC) loss so measure after the sun goes down and again early the next morning.
3) you measure minimal (<= 0.5 ppm) Combined Chlorine (CC).

After all three have occurred, you have completely gotten rid of the algae. If you lower the chlorine too soon, the algae can come back as it could overwhelm the lower chlorine levels (if there's still enough algae to do so). Remember that low concentrations of algae are NOT visible, but do show up as additional chlorine demand. Then higher concentrations make the water look dull, then cloudy, and finally green. It takes a lot of algae to get to the green stage and the algae only double in population every 3-8 hours so it takes days to actually develop an algae bloom from the time it first originates with a low chlorine level (relative to CYA). It's similar to the reverse of the photos in this link though the process is different because in killing the algae the bleach does literally bleach out the chlorophyll to make the algae turn gray. Nevertheless, diffuse low concentrations of algae just make water look dull or cloudy.

As for what to do -- continued brushing to remove any biofilms stuck to pool surfaces, keep the pump running to turnover water through the filter, cleaning of the filter (backwash or wash, depending on filter type) to remove dead algae caught in it.

If you have a pool without a floor drain (such as most above-ground pools) or the pool has poor circulation, then you can consider using a flocculant such as OMNI Liquid Floc Plus which (after adding it and turning off the pump) will consolidate the dead algae and cause it to drop to the bottom of the pool where it can be vacuumed to waste (assuming you have that option). This is not necessary if your pool has good circulation and you can get everything into the filter. If you had a LOT of algae, such as the link I gave above showing a pool upon spring opening that was "let go" over the winter, then vacuum to waste is more efficient to remove large quantities of dead algae, but in that case a flocculant isn't usually needed (as you could see from the photos, large quantities of dead algae just dropped to the bottom of the pool on their own).

Richard

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