Algae Problem

Algae problems in swimming pool water.
Green (cloudy) water or slimy pool walls.
Black algae. Mustard algae. Pink or white pool mold.
cajunslo
Pool Newbie
Pool Newbie
Posts: 9
Joined: Wed 22 Jul, 2009 13:06
My Pool: Above Ground, 6' , 18' round. 325# inground type sand filter and pump.
Location: Louisiana

Algae Problem

Postby cajunslo » Wed 22 Jul, 2009 13:40

Algae has taken over our pool. Louisiana the last couple of months has been really hot. I suspect that we let our chlorine levels get to low. Initially I followed the BBB method for a couple of years until the wife got confortable taking care of HER pool. I had the test kit ordered on line, showed her how to use it and everything worked fine, until she decided it was earier to bring a sample to the pool store. She continued to use the bleach to shock the pool, but also added things in the past that the pool store suggested. I let her do as long as the pool was clear. However it started to turn a shade of light green, then dark green. We use a inline chlorinator with 3" tablets, not sure what kind at this time. She has shocked it two days in a row, brushed and vaccumed.
Todays readings, from pool store.
FC - 9.1
TC - 12.0
CC - 2.9
PH - 7.7
CA -64
TA - 100
Ajs. A - 79

Above ground Pool, 16800 gal.
Any advice would be greatly appreciated.


chem geek
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Joined: Thu 21 Jun, 2007 21:27
Location: San Rafael, California

Algae Problem

Postby chem geek » Wed 22 Jul, 2009 23:51

Is the green color fairly clear or is it cloudy? If fairly clear, then I suspect copper in the water. If you lower the pH and it gets more clear then that's likely what it is and you'll need to add a metal sequestrant. See if one of the products your wife added to the pool was a copper-based algaecide which was likely the source of the copper. When the pH rose, the copper precipitated.

If instead the water is cloudy green or the green looks like algae clumps, then this may have happened from continued use of Trichlor pucks. For every 10 ppm Free Chlorine (FC) added by Trichlor, the pucks will increase Cyanuric Acid (CYA) by 6 ppm. So even with a low 1 ppm FC per day chlorine usage, the CYA will increase by over 100 ppm in 6 months if you do not have significant water dilution.

I wouldn't trust the pool store numbers at all. Is the CA calcium hardness or cyanuric acid level? I suspect it's Calcium Hardness (CH) since the pool is above-ground and probably vinyl lined so doesn't need much extra calcium. Why didn't they measure the CYA level? I suspect it is very high which makes the chlorine not very effective. Though your chlorine level is high now, it probably wasn't before you shocked the pool so the chlorine wasn't able to kill the algae faster than it could grow. You really should get your own good test kit -- either the Taylor K-2006 you can get at a good online price here or the TF100 from tftestkits.net here and find out your CYA level. If it's high (> 80 ppm) then do a partial drain/refill to lower it. It will make shocking with chlorine to kill the algae easier. Read Defeating Algae to learn how to clear the pool of algae.

Richard
cajunslo
Pool Newbie
Pool Newbie
Posts: 9
Joined: Wed 22 Jul, 2009 13:06
My Pool: Above Ground, 6' , 18' round. 325# inground type sand filter and pump.
Location: Louisiana

Algae Problem

Postby cajunslo » Thu 23 Jul, 2009 04:48

Thanks for the response.

My bad on the CYA level, its has been awhile since i used the pool lingo.

They did measure both the CYA and Calcium Hardness.

I didn't mention the CH since in the past i was told it was not that big a deal with a vinyl pool.

CH - 150
CYA- 64

The pool is more like a dark green. My say's she was using just the bleach to shock with.
However since it was real hot, I had adjusted the inline chlorinator from a setting of 2 to 3.5.
this was done only after the pool was green. We use to run it at 1. I thought we would loose all of our
stabilizer with the extra hot summer we are having. My pool does not get any shade. The only foreign
matter entering the pool is when we cut the grass, it gets alot of dust, etc. from that.
cajunslo
Pool Newbie
Pool Newbie
Posts: 9
Joined: Wed 22 Jul, 2009 13:06
My Pool: Above Ground, 6' , 18' round. 325# inground type sand filter and pump.
Location: Louisiana

Algae Problem

Postby cajunslo » Thu 23 Jul, 2009 04:59

Forgot to mention I do have my own test kit.
I did researce on a sight like this one prior to buying our pool.
I ended up buying one of the kits, i dont recall the brand at this time.
But is cost around 75.00 and tested everything we needed. However
I work away from home on a 7 & 7 rotation so my wife had to depend on
using it. She is partially handicapped so only has the use of one hand. She can
use the test kit, but once she got the hang of just using bleach and tablets she
quit using the kit and started bringing samples to the pool store.
cajunslo
Pool Newbie
Pool Newbie
Posts: 9
Joined: Wed 22 Jul, 2009 13:06
My Pool: Above Ground, 6' , 18' round. 325# inground type sand filter and pump.
Location: Louisiana

Algae Problem

Postby cajunslo » Thu 23 Jul, 2009 06:06

More info - The pool store sold my wife some CB 7 and a clarifier. I looked up some information this morning and found out the CB 7 is a Haviland product, algae killer with cooper. I told her not to add anything last night and stick with the bleach. She added 3 jugs of bleach and will get more today. Once we get the algae problem solved, i would like a little help with maintenance tips that my wife could follow since
i work away from home. thanks again.
cajunslo
Pool Newbie
Pool Newbie
Posts: 9
Joined: Wed 22 Jul, 2009 13:06
My Pool: Above Ground, 6' , 18' round. 325# inground type sand filter and pump.
Location: Louisiana

Algae Problem

Postby cajunslo » Fri 24 Jul, 2009 08:21

Took two white buckets with pool water. Poured approx. 2 cup acid in one and 2 cups bleach in the other.
The bleach bucket remained the same and the muratic acid turned the green water clear. Added about
1/2 gal. to pool last night , have been circulating 24/7. Did not see any change this morning . Will have
numbers later today. Please advise.
chem geek
Pool Industry Leader
Pool Industry Leader
Posts: 2382
Joined: Thu 21 Jun, 2007 21:27
Location: San Rafael, California

Algae Problem

Postby chem geek » Fri 24 Jul, 2009 11:23

Since the bleach did not clear the green but the acid did, that would indicate too much copper in the pool. You could lower the pH in the pool (not below 7.0, however) and add metal sequestrant -- get the type that says it's HEDP or phosphonic acid or a similar sounding name (not EDTA). Then very slowly raise the pH. You can read Metals in the Water and Metal Stains for more info.

It sounds like too much copper-based algaecide was used over time. Unfortunately, the metal sequestrant just prevents the copper from staining or coloring the water too much, but it doesn't remove it. Only dilution with metal-free water will remove the copper. You will need to keep adding a weekly maintenance dose of metal sequestrant since it slowly breaks down from chlorine.

As for how to maintain the pool on an ongoing basis, read the Pool School . You'll just add chlorine regularly to maintain the appropriate FC level relative to the CYA level.

By the way, how do you get a 64 ppm CYA level in your test? The turbidimetric test only has gradations for 10 ppm so at best you can estimate perhaps halfway. Are you using a Taylor K-2006 test kit or a TF100 kit from tftestkits.net?
cajunslo
Pool Newbie
Pool Newbie
Posts: 9
Joined: Wed 22 Jul, 2009 13:06
My Pool: Above Ground, 6' , 18' round. 325# inground type sand filter and pump.
Location: Louisiana

Algae Problem

Postby cajunslo » Fri 24 Jul, 2009 12:23

64 was from the pool store. PINPOINT Computerized Analysis System

Todays Readings

Saturation Index -0.47
Disolved Solids 0
Free Chlorine 7.7
Total chlorine 8.2
Combined Chlorine 0.5
PH 7.2
Cyanuric Acid 50
Cooper 0.1 ( Pool Store told my wife the cooper came from the muratic acid )
Iron 0
TA 85
Adj TA 68
Calcium Hardness 150

Pool Store Recommendation - Add CB-7 8-10 oz thru skimmer run 24/7 dont back wash for 2-3 days.

Told them about the test I had my wife do and they said we were dealing with two different chemicals, Da !

What would you do ?
cajunslo
Pool Newbie
Pool Newbie
Posts: 9
Joined: Wed 22 Jul, 2009 13:06
My Pool: Above Ground, 6' , 18' round. 325# inground type sand filter and pump.
Location: Louisiana

Algae Problem

Postby cajunslo » Fri 24 Jul, 2009 12:24

Oh, The pool was still green this morning.
I asked my wife if the pool sides and bottom felt slimmy when she was brushing walls and bottom
and she said no.
chem geek
Pool Industry Leader
Pool Industry Leader
Posts: 2382
Joined: Thu 21 Jun, 2007 21:27
Location: San Rafael, California

Algae Problem

Postby chem geek » Fri 24 Jul, 2009 19:28

The copper did not come from the Muriatic Acid (not unless you poured it into the skimmer and ruined your copper heat exchanger in a gas heater).

I wouldn't trust the pool store numbers at all. If I were you, I would get one of the good test kits I recommended so you'll know where you really stand. I would lower the pH to 7.0 and then add HEDP metal sequestrant to the water as directed and until it clears and would then very slowly have the pH rise (you can use 20 Mule Team Borax for that).

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