Bleach

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

algae

Postby thinkpool » Mon 18 Aug, 2008 17:06

:oops: Sorry, CYA=150 based on the test kit indicating that "black dot" starting to disappear...
So, I went to the pool place for water sample test, and the result showed CYA=25 (they say the "black dot" indicator should disappear); they use a stick with level indicator to measure CYA.

Pool place recommendation:
10.5 lbs of Balance Pak 100
1.5 lbs Lo & Slo
3 lbs of Stabilizer
4 bags of Burnout
1 bottle of Banish


chem geek
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Algae

Postby chem geek » Mon 18 Aug, 2008 17:19

Did you use a Taylor test kit for testing CYA and did you use the readings on the back of the tube as shown here ? Did the CYA test proceed as shown in this link ? If you added a lot of liquid before the black dot disappeared, then the CYA level is low and the pool store is correct. How did you get to a measurement of 150 when you did the test?

If the CYA is low as the pool store indicates, then if your FC is high and the green persists, then it is more likely to be copper, especially if it's a clear green. Try lowering the pH. If the green gets more clear, then this is very likely to be copper and adding a metal sequestrant when you are at low pH will help though over time you're going to have to replace your water through periodic dilution (partial drain/refill). To make sure that this is what you've got, have the pool store test for copper. Did they do that?

Balance Pak 100 is identical to Arm & Hammer Baking Soda. You didn't say the size of your pool, but 10.5 pounds in 15,000 gallons would raise the TA by 50 ppm which is a lot. You didn't say what your TA level was. In fact, you didn't explicitly list any of your levels which makes it very hard to tell you what to do. I would NOT trust the pool store with their numbers -- very often they are wrong.

Lo & Slo is Sodium Bisulfate which is aka dry acid and will lower pH. You can use Muriatic Acid you can get at a hardware store instead and won't add sulfates to the water. The 1.5 pounds in 15,000 gallons would lower pH from around 7.6 to 7.4.

3 pounds of stabilizer in 15,000 gallons would raise the CYA by 24 ppm.

BioGuard BurnOut is lithium hypochlorite which is the most expensive form of chlorine there is. Bleach or chlorinating liquid is FAR less expensive and accomplishes exactly the same thing -- it's just heavier to carry since it's mostly water.

Banish is a copper-based algaecide so if you've got copper in your pool already it's definitely not the thing you want to use and even if you don't already have copper you can stain your pool by adding it. Do NOT use this algaecide.

For clearing a pool of algae, read this link from The Pool School I linked to earlier. However, it's still not clear whether you have algae or not -- are you sure it is algae? Is the water dull/cloudy green or is it a clear green? You said it was mustard green which is a color, but didn't describe the clarity of the water.

Again, I strongly encourage you to get your own good test kit and take control of your water; otherwise, you will be at the mercy of the pool store and will spend a lot of money on your pool which may or may not work at helping you, depending on the competency of the pool store. The only test I would have the pool store do is to test for metals (copper, iron).

By the way, 2.7 gallons of unscented Clorox Regular 6% bleach in 15,000 gallons would be 11 ppm FC which isn't very high for fighting algae if the CYA is high and even if the CYA is low you need to keep adding chlorine to keep the FC up. If algae is present, it will consume chlorine quickly so you need to keep testing FC and adding more. With the test kits I linked earlier, you can test high chlorine levels easily up to 50 ppm. With regular chlorine test kits, you cannot easily test above 5 ppm FC.

Richard
thinkpool

algae

Postby thinkpool » Mon 18 Aug, 2008 17:47

Thanks for responding so quickly... really appreciated your expertise..
The way I tested CYA (HTH test kit), I stopped at midpoint as you showed pictorially, which was my misunderstanding of "starting to disappear" and guesstimated since its half way to "100".

Pool looked "mustard green and cloudy"; however, water showed just slightly cloudy in test bottle.

Unfortunately, the pool place unable to print due to printer mulfunction.
Pool place said I have zero chlorine, TA low, pH=7.8 and CYA = 25; and, recommended the chemicals to add.
10.5 lbs of Balance Pak 100
1.5 lbs Lo & Slo
3 lbs of Stabilizer
4 bags of Burnout
1 bottle of Banish

I looked at your CYA/FC chart and followed the amount FC needed is 12.7 ppm. So, based on Pool Calculator I need 4 gals of bleach (6%).
Do I need to bring up TA before adding bleach?

I am not sure if I missed any info you needed.
Thanks in advance for your advse.
Guest

Re: algae

Postby Guest » Mon 18 Aug, 2008 18:43

[quote="thinkpool"]Thanks for responding so quickly... really appreciated your expertise..
The way I tested CYA (HTH test kit), I stopped at midpoint as you showed pictorially, which was my misunderstanding of "starting to disappear" and guesstimated since its half way to "100".

Pool looked "mustard green and cloudy"; however, water showed just slightly cloudy in test bottle.

Unfortunately, the pool place unable to print due to printer mulfunction.
Pool place said I have zero chlorine, TA low, pH=7.8 and CYA = 25; and, recommended the chemicals to add.
10.5 lbs of Balance Pak 100
1.5 lbs Lo & Slo
3 lbs of Stabilizer
4 bags of Burnout
1 bottle of Banish

I looked at your CYA/FC chart and followed the amount FC needed is 12.7 ppm. So, based on Pool Calculator I need 4 gals of bleach (6%).
Do I need to bring up TA before adding bleach?

I am not sure if I missed any info you needed.
Thanks in advance for your advse.[/quote]

water volum = 19.8 k gals (16x30 in ground pool)
chem geek
Pool Industry Leader
Pool Industry Leader
Posts: 2382
Joined: Thu 21 Jun, 2007 21:27
Location: San Rafael, California

Algae

Postby chem geek » Mon 18 Aug, 2008 19:22

I can't say whether you need more TA since "low" doesn't mean very much. I suppose it wouldn't hurt to add half of what they said, so 5 pounds of Arm & Hammer Baking Soda (unless you don't mind spending more for the Balance Pak 100). It's easy to raise the TA, but harder to lower it.

If I were you, I'd redo your CYA test in your HTH kit but read it now that you know what to look for. If the CYA were really 25, then it will go all the way up to the top of the tube and you'll still barely see the black dot since the top of the tube is near 30 ppm CYA.

If your CYA is really that low, then I'd just target 15 ppm FC, but the key is to keep adding chlorine every hour or so if the FC drops. Also, brush the pool to get the algae circulating with the chlorine. You may need to clean your filter if the pressure goes up when it clears dead algae. Your pool should go from green to gray (or aqua-gray or pale-green-gray) if you are doing things correctly. See this link for how a pool with lots of algae upon spring opening gets cleared using chlorine alone.

Richard
thinkpool

algae

Postby thinkpool » Tue 19 Aug, 2008 10:00

:( I added about 4.8 gals of Chlorox to 19.8K gal of pool water last night. Well, water in pool looked the same this morning. I am at a total lost now. What to do next? I have "quick dissoving shock" by PoolBrand. I am thinking of dumping 5 bags tonight and see if it makes any difference. Or, I can get HTH brand super shock to try. Please advise.
chem geek
Pool Industry Leader
Pool Industry Leader
Posts: 2382
Joined: Thu 21 Jun, 2007 21:27
Location: San Rafael, California

Algae

Postby chem geek » Tue 19 Aug, 2008 10:25

IF you have algae, then you add chlorine and then test in an hour or so. If the FC has dropped, you add more chlorine. You don't just dump some in and stop there. Also, you never retested your CYA level so we don't know what it really is. If it's very high, then smaller amounts of chlorine (10-15 ppm FC or so) aren't going to help very much and it will be more worth it to do a partial drain/refill to lower the CYA level. Finally, you never got your water tested for copper to see if that is what is causing the green and you never tried lowering the pH to see if that reduced the intensity of green (which it would if it were copper).

I've given you links to The Pool School where they describe in detail how to get rid of algae, but we haven't determined if that's what you have in your pool. You really need to retest the CYA level.

If you use the copper-based algaecide the pool store recommends, then if you've got algae it will kill it but if you use too much then the water can turn green from the copper and you can get stains on pool surfaces; and if you already have copper in the pool then the copper-based algaecide will make that problem worse.

Richard
thinkpool

???? algae

Postby thinkpool » Tue 19 Aug, 2008 11:38

:( Well, I had a good reason of not retesting CYA again... I ran out of Cyanuric Acid Reagent . I refenced the CYA value from the pool store. I will get another sample of h2o to a dfferent pool store for CYA, etc., and metal. I'll love to have the crystal clear blue h2o again!!
chem geek
Pool Industry Leader
Pool Industry Leader
Posts: 2382
Joined: Thu 21 Jun, 2007 21:27
Location: San Rafael, California

Algae

Postby chem geek » Tue 19 Aug, 2008 15:10

Here's something you can do as a test. If you take a large bucket of pool water from the darkest green section of the pool, does it show up as green in the bucket (use a white bucket if you have one)? If it does, then you can add bleach to it to see if it turns cloudy and then clears. If so, then it's algae and chlorine will kill it (though if the CYA is high it will take too much chlorine to do so partial drain/refill is better). If not, then it's probably not algae (most likely is copper).

Repeat the test, but add acid to the bucket. If it clears, then it's copper and the procedure for clearing it would be lowering the pH, adding a metal sequestrant, then slowly raising the pH to normal.

It's much easier to test a small volume of water in a bucket than trying to test the entire pool.

If you add chlorine to the pool and the FC drops within hours (even when the sun isn't shining on the pool), then it's most likely you have algae and need to keep adding chlorine to keep the FC up. But as I said, if the CYA level is very high then this would take too much chlorine.

Again, you should get your own good test kit -- the Taylor K-2006 you can get at a good online price here or the TF100 kit from tftestkits(dot)com here with the latter kit having 36% more volume of reagents so is comparably priced "per test".

Richard
thinkpool

Cl

Postby thinkpool » Fri 22 Aug, 2008 15:01

I am testing Cl level using HTH OTO. The color in test tube turned ORANGE. pH side indicates 7.2 level. :shock: Please advise.

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