dark green pool - how do I clean it??

Algae problems in swimming pool water.
Green (cloudy) water or slimy pool walls.
Black algae. Mustard algae. Pink or white pool mold.
pool911help

green pool

Postby pool911help » Wed 06 Aug, 2008 07:54

is bleach the same thing as liquid chlorine?


Guest

How to clean a green pool

Postby Guest » Thu 19 Mar, 2009 04:13

This topic may be old but I found all the info I was looking for. :thumbup:

Now to clean my green pool. :thumbdown:
chem geek
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Dark green pool - how do I clean it??

Postby chem geek » Thu 19 Mar, 2009 09:40

The key to battling the algae, in addition to physical removal, brushing and filtering/backwashing, is to MAINTAIN a high FC level relative to the CYA level (an FC around 40% of the CYA level). If the CYA is already high, then doing a partial drain/refill first to dilute it will let you use a lower FC target which is usually easier and faster. See this link for more info on defeating algae.

Bleach and chlorinating liquid are the same except for strength of the chlorine. Clorox Regular and most off-brand Ultra bleaches are 6% (not 9%) and is 5.7% Available Chlorine. Off-brand regular bleaches may be only 3%. Most bleaches except for Clorox Regular unscented have too much excess lye in them so would make the pH rise over time. You may be able to get 10% or 12.5% chlorinating liquid from your pool store or hardware/big-box store. It is true that these are heavier to carry than other sources of chlorine because they are mostly water, but the chlorine is sodium hypochlorite and does not increase either the Cyanuric Acid (CYA) level nor Calcium Hardness (CH).

For every 10 ppm Free Chlorine (FC) added by Trichlor, it also increases Cyanuric Acid (CYA) by 6 ppm.
For every 10 ppm FC added by Dichlor, it also increases Cyanuric Acid (CYA) by 9 ppm.
For every 10 ppm FC added by Cal-Hypo, it also increases Calcium Hardness (CH) by 7 ppm.

So you don't want to use the stabilized chlorine (Trichlor or Dichlor) products for shocking since the higher CYA just makes the chlorine less effective. You can use Cal-Hypo if your CH level isn't already high. If your water is already saturated with calcium carbonate (i.e. the saturation index is near or greater than zero) then you may find the water gets cloudy when using Cal-Hypo. This can dissipate over time, but can get confusing when trying to battle algae. See The Pool Calculator for calculating the saturation index and for dosing amounts.

A more concentrated form of chlorine that doesn't add CYA nor CH is Lithium Hypochlorite which is 35% available chlorine, but it is VERY expensive. A cost comparison of chlorine sources may be found here . Though bleach and chlorinating liquid are heavier to carry, they are less expensive in the long-run especially when accounting for long-term pH adjustment required from other sources (e.g. Trichlor).

When shocking with a hypochlorite source of chlorine, it may be a good idea to lower the pH of the water first to around 7.2 or so. The addition of the chlorine will make the pH rise and though it will come back down as the chlorine gets used up, the chlorine will be more effective if the pH doesn't rise so much. The CYA in the water will help buffer the effectiveness of the chlorine at higher pH, but there is still an effect on the pH on chlorine. The graphs in this post show the effect of pH on "active" chlorine (hypochlorous acid) concentration without and with CYA in the water.

As for the comment that algaecides are for preventative use and not for killing an existing algae bloom, that is true for most except for the copper-based algaecides which are effective at killing existing algae. However, you then have to deal with the possible side effects of staining associated with high levels of copper and high pH.

Richard
bweihl
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My Pool: not sure of exact size. it a below ground pool. A little smaller than most. Tile bottom, no liner
Location: florida

Dark green pool - how do I clean it??

Postby bweihl » Tue 21 Apr, 2009 08:35

Hi there,
My pool is green and I want to know the cheapest but best way to fix it. I know that's a tall order but I dont have lots of money to buy all kinds of stuff at a pool store!
I dipped a test strip in and these are the results:
Free Ch: Very low, strip is white
pH: between the 7.8 and 8.4 color
Total alkalinity 40
Cyanuric acid: low, close to the 0 color

Please help!
Thanks
Bena'
chem geek
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dark green pool - how do I clean it??

Postby chem geek » Tue 21 Apr, 2009 09:42

Actually, Clorox Regular unscented is 6% sodium hypochlorite as are most off-brand Ultra bleaches. However, once in the water, the chlorine from ALL sources is IDENTICAL. The price per weight for bleach and chlorinating liquid is far less than for other sources of chlorine so yes, you have to use more by weight, but all that matters is that you raise the Free Chlorine (FC) to shock level -- the source of the chlorine doesn't matter except that you'll get EXTRA items you may not want with other chlorine sources.

A cost comparison of chlorine sources is here where you will see that Cal-Hypo is about the same price as typical chlorinating liquid and sometimes a little more expensive than bleach.

Just keep in mind the following chemical facts if you use a different source of chlorine:

For every 10 ppm Free Chlorine (FC) added by Trichlor, it also increases Cyanuric Acid (CYA) by 6 ppm.
For every 10 ppm FC added by Dichlor, it also increases CYA by 9 ppm.
For every 10 ppm FC added by Cal-Hypo, it also increases Calcium Hardness (CH) b 7 ppm.

Did you read Defeating Algae and do you know the CYA level in your pool? If the CYA is very high, it may be better to do a partial drain/refill first to lower the CYA level since it will take a lower FC level to kill algae in that case.

Richard
bweihl
Pool Newbie
Pool Newbie
Posts: 3
Joined: Mon 20 Apr, 2009 16:28
My Pool: not sure of exact size. it a below ground pool. A little smaller than most. Tile bottom, no liner
Location: florida

Dark green pool - how do I clean it??

Postby bweihl » Tue 21 Apr, 2009 12:04

My pool is green and I want to know the cheapest but best way to fix it. I know that's a tall order but I dont have lots of money to buy all kinds of stuff at a pool store!
I dipped a test strip in and these are the results:
Free Ch: Very low, strip is white
pH: between the 7.8 and 8.4 color
Total alkalinity 40
Cyanuric acid: low, close to the 0 color

Please help!
chem geek
Pool Industry Leader
Pool Industry Leader
Posts: 2382
Joined: Thu 21 Jun, 2007 21:27
Location: San Rafael, California

dark green pool - how do I clean it??

Postby chem geek » Tue 21 Apr, 2009 19:57

1) Get a good test kit -- read this for good ones.

2) Read and follow Defeating Algae .

If you are just opening the pool and you had CYA in the water before you closed but now it's gone, then it can take a LOT of chlorine before the chlorine starts to hold. Add 10 ppm FC at a time until it starts to hold, and then you can balance the rest of the water. But order the test kit right away.

You can also add a small amount of CYA (say, around 20 ppm until you get your test kit) to protect your chlorine from breakdown in sunlight, but since your test results may not be accurate, I'd be careful not to overdo it.
Bobbyg714

Dark green pool - how do I clean it??

Postby Bobbyg714 » Mon 11 May, 2009 12:54

I too am having the same issue with a dark green pool and also no main drain. I don't have my water test results in front of me but will add later. I am a novice owner and have battled algae last year and have a big "uncovered" problem this year. When you are talking about using bleach, what type of bleach are you referring to? Laundry Bleach? Sorry if this is a dumb question but I am so frustrated with this pool and the algae that anything is worth a shot. My pool is in-ground with a vinal liner and 23,000 gallons. I currently have a sand filter but just purchased a Hayward Pro-grid 60sq ft D.E filter hoping that would solve my issues with algae. I am hoping to have teh water cleared prior to swapping filters. Since I uncovered yesterday Leslies had me add an algaecide and 3 pounds of power plus shock. Any help would be greatly appreciated. Thank you in advance.
chem geek
Pool Industry Leader
Pool Industry Leader
Posts: 2382
Joined: Thu 21 Jun, 2007 21:27
Location: San Rafael, California

dark green pool - how do I clean it??

Postby chem geek » Mon 11 May, 2009 21:20

Since you have a vinyl pool and your Calcium Hardness (CH) level is probably not high, the recommendation of using Power Powder Plus for shocking the pool is not bad. I was only suggesting that you could also use chlorinating liquid from a pool or hardware store or 6% bleach (Clorox Regular unscented) instead, though it's really up to you. Just keep in mind that for every 10 ppm Free Chlorine (FC) added by Cal-Hypo (as found in Power Powder Plus), it also increases Calcium Hardness (CH) by 7 ppm. That's OK if your CH isn't too high already.

Please read Defeating Algae and please get yourself a good test kit, either the Taylor K-2006 you can get at a good online price here or the TF100 from tftestkits.net here with the latter kit having 36% more volume of reagents so is less expensive per test.

Since your pool does not have a floor drain, then after you kill the algae you may have cloudy water that takes long to clear. If that happens and you aren't patient with brushing, filtering, backwashing, then you can use a flocculant and vacuum-to-waste the resulting precipitate of dead algae.

Richard
Bobbyg714

Dark green pool - how do I clean it??

Postby Bobbyg714 » Tue 12 May, 2009 05:26

Richard,
First I would liek to say thank you for taking the time to reply. You have no idea how much I appreciate any help I can get with this issue I am so frustrated these past two seasons with teh algae. Here is some updated information. Leslies tested the water prior to any chemicals and here is what I had

FAC 0
TAC 0
PH 7.2
TA 111
Cal Hardness 310
CYA 40
TDS 750

So they had me add soda ash and algaecide and shock. I used test strips ( I will order the test kit you recommended today) and my FC was still 0 and my PH was 7.8. I then went to another store and they gave me 5 gallons of liquid chlorine. I added that last night along with two bags of Powder Plus. Using the test strips it shows a FAC as high like 10 this morning. The pool however looks no different. It is still dark green and not even close to being able to see the bottom.

Another question I had was should I get the hand vacuum and set that up and sit it on the bottom of the deep end and use that as a main drain to get a better flow?

Bob

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