please help! Cant keep algae away

Algae problems in swimming pool water.
Green (cloudy) water or slimy pool walls.
Black algae. Mustard algae. Pink or white pool mold.
anjellenee
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please help! Cant keep algae away

Postby anjellenee » Wed 11 Jul, 2007 01:34

Hi,

I am a new pool owner.
I have:
[list=]above ground pool
hayward pump and filter (running 24/7)
doughboy skimmer (just replaced basket, old basket was cracked but we had it tied up pretty well with cable ties but i wouldnt doubt something could've got pulled into filter befor ei realized basket was cracked-I also check basket daily and empty)
also just bought a vacuum but havent used yet because still got algae and it says dont run with algae
Pool is oval 32x16 and is about 3-3.5' deep
Floating chlorine holder using 1" mini tabs (maybe 10 in there) [/list]

The pool keeps getting green with algae. I've resurrected it a few times but it seems to only take another week or so to go back. I couldnt tell you how I revived it but I know I had to shock at least 3x (with 2lb each). Let me also mention I had calcium hypochlorite left by previous house owners and i was told by pool people this could be used as shock. I also treated water with PH increaser as recommended when I first got water tested after moving in.

Now I have my own test strips and have been testing. Here is what I have done so far:
Shocked twice (two days in a row)
half ass loosened algae with net before first shock, bought brush and brushed before second shock, and thoroughly today before algaecide)
applied algaecide
keeping chlorine in there (3 1" tabs disappeared in about 2 days)

My test strips reveal
Water hardness: 250 OK
Chlorine: 1 OK
Free Chlorine: 0 very low
PH: 8.4 very high
alkalinity: 40 low
stabliizer: 50 ok

Would high ph cause chlorine to keep getting eaten up? is this why algae wont go away? does high ph encourage algae?

Its obvious to me now that i need to decrease this ph so i will be buying chem tomorrow but could this have been the problem the whole time? my thought was algae kept coming back because we had a lot of residue on bottom of pool that i was not able to get up with leaf rake alone. and that this residue was turning to algae. finally ive got my vaccuum and the damn thing went green again. is there anything else i should be doing. i think i've included every detail available.

please help!


Backglass
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Postby Backglass » Wed 11 Jul, 2007 07:54

With a CYA of 50, if you don't have at least 3ppm of Chlorine in your pool at all times, algae will grow. You have -0- free which isn't just "low", it's none. :shock:

You need to get your pool to shock levels (10ppm) and keep adding chlorine until you can keep it there for 24 hours. Run your pump/filter 24/7.

Stop using chlorine pucks. They will add to your CYA which is already at the high limit (30-50). Use liquid chlorine instead (Bleach).
anjellenee
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Postby anjellenee » Wed 11 Jul, 2007 18:54

ok so whats cya? stablizer? u mean put household bleach in there? like clorox? or something from the pool store?
South TX Poolguy
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Postby South TX Poolguy » Wed 11 Jul, 2007 23:20

Backglass wrote:They will add to your CYA which is already at the high limit (30-50).


Man you must live in a perfect world. I wish the pools I take care of had only 50 CYA.

OP, Yes you can use plain unscented bleach or buy shock from a store.
chem geek
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Location: San Rafael, California

Postby chem geek » Thu 12 Jul, 2007 14:01

South TX Poolguy,

It is true that pools that use Trichlor tend to go pretty high in CYA, especially if there is not significant dilution from splash-out or backwashing or rain overflow. Pools with cartridge filters in dry summer climates without an opaque pool cover (so the UV from sunlight breaks down a lot of chlorine) tend to climb in CYA very quickly.

To avoid algae, your pool users have several choices:

1) They can increase the Free Chlorine (FC) level with the higher CYA level. The FC level target should be 11.5% of the CYA level to keep away green algae with an absolute minimum of 7.5% of the CYA level at all times.

2) They can use a lower FC level, say 3 ppm, as a target, but need to add some sort of algaecide. A weekly maintenance dose of PolyQuat 60 is best, but other options are available though may have side effects. For example, copper kills and inhibits algae, but can precipitate at high pH to cause green tint in the pool (from copper hydroxide) or can make blond hair turn green. 30-50 ppm Borates (from 20 Mule Team Borax or Proteam Supreme, etc.) can be used in the pool as this is an algaecide, but we don't have good data for how effective this is -- it may not be as good as PolyQuat 60 which keeps away green algae even when there is no chlorine at all.

3) They can regularly dilute the pool water through more frequent backwashing or partial drain/refill to keep the CYA level lower.

4) They can switch to using a source of chlorine that does not add CYA. For every 1 ppm FC from Trichlor you also get 0.6 ppm CYA. For every 1 ppm FC from Dichlor you also get 0.9 ppm CYA. Unscented bleach and chlorinating liquid do not add any CYA. Cal-Hypo doesn't either, but does increase Calcium Hardness (CH) -- for every 1 ppm FC from Cal-Hypo you also get 0.7 ppm CH.

The downside to not using Trichlor is that you have to add the chlorine every day unless you have a pool cover opaque to UV rays from the sun in which case you can add chlorine 2-3 times per week. Another option is to use The Liquidator for automatic dosing of bleach or chlorinating liquid -- some pool owners have started using this and so far are quite happy with it.

Richard
South TX Poolguy
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Postby South TX Poolguy » Thu 12 Jul, 2007 22:12

1) They can increase the Free Chlorine (FC) level with the higher CYA level. The FC level target should be 11.5% of the CYA level to keep away green algae with an absolute minimum of 7.5% of the CYA level at all times.


Thanks for this bit of info. It should be a *note whenever someone states chlorine should be between 1 and 5.
chem geek
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Postby chem geek » Thu 12 Jul, 2007 22:40

The industry (i.e. manufacturers of Trichlor and Dichlor) do not agree with the "FC as a percentage of CYA" rule even though they understand and acknowledge the chemistry behind it. They believe it doesn't apply to "real" pools. I discuss this and the study they use to justify their position in this thread .

Richard
Fiona Walker
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How do I keep algae at bay without chlorine?

Postby Fiona Walker » Sun 29 Jul, 2007 10:02

I have real problems stopping algae in my EcoSmarte pool - may be high pH (since I'm yet to remotely get to grips with the difference with total alkalinity).... fill water is 8.2, test comes back at consistently 7 or possibly 6.8 yet still getting algae bloom. Any suggestions? I've tried dosing with HCl but not pooling - would that be the problem? Help!
Backglass
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Postby Backglass » Mon 30 Jul, 2007 10:12

South TX Poolguy wrote:Man you must live in a perfect world. I wish the pools I take care of had only 50 CYA.


I'm sure your clients wish that too. ;)

Hey...at least you have job security returning to fix their algae blooms huh!

FIONA: Please start a new topic thread for your problems. It's easier to keep track that way instead of multiple people/problems in the same topic.
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