New User

[austinpooldude]

Hi Folks ....

I've been a pool owner for about 15 years, and after learning about tfp I decided to give the BBB method a try.

My current situation: CYA is high (90) despite the fact that I did a 95% drain in July 2009, and have been careful to avoid re-adding CYA through the 3" chlorine pucks or the granular shock. After doing such a large drain I added CYA to get a base level in the water again, and I thought by avoiding excessive use of the pucks I'd get 2-3 years before I reached a high CYA level again.

My water is crystal clear, but I have a widespread, persistent growth of light green algae that can be easily brushed away. I also have over the past year started to get black algae, which does seem to go away with brushing and high chlorine levels. But my reluctance to add the CYA has caused me to avoid shocking too much and avoid putting 12-15 pucks in each week, which is about what it would take to maintain the chlorine level to eliminate the black algae.

I have purchased the TF-100 test kit, and results are:
FC 7
CC .5
CYA 90
PH 7.2

I'm looking for advice before I proceed. I suspect I should replace about 50% of the pool water, and only then start attacking the algae issues. Does this make sense?

Other questions:
a) in last summer's draining I shocked before draining, brushed the walls to remove algae, and then drained using pump on backwash cycle, which took about 2 hours. I've since learned that CYA can 'stick' to the walls and it's important to brush and rinse them as the pool is draining. Is that important?

b) My pool is gunite and about 10 years old. I can't seem to get the PH up above 7.2, although I'm sure I could if I kept adding sodium carbonate (left over chemical from before BBB). Pool store said 7.2 was good enough, and there are no complaints from any swimmers.

I appreciate any suggestions folks may offer. Not sure if it's pertinent, but the pool is increasingly covered with trees. From January through end of May this year there was large daily amounts of leaves, seeds, and pollen in most weeks. During this time I had switched from traditional DE to using Zeo-Fiber, and it just didn't work out. I had to disassemble the filter and hand wash the filter panels almost weekly. Seems that Zeo-Fiber will clog up filter 4-5x faster than DE will. I kept at it, thinking that I was removing longterm particles that had been circulating, but I eventually concluded that for my situation, Zeo-Fiber won't work as well as traditional DE.

 

[JasonLion]

Yes, replace water to bring CYA down, then fight the algae. Also, stop using trichlor, or at the very least use less trichlor.
a) no it is not important to brush the pool walls.
b) A PH of 7.2 is good enough but it leaves you open to risks of having the PH go to low. Again, this is really a problem with using trichlor, which is constantly lowering the PH.

 

[duraleigh]

Hey, there, APD,

Welcome to the forum. :lol:

Your situation is pretty common but it's also going to be easy to get your pool back to crystal clear with no algae.

You are spot on in doing another drain. In your climate, I would suggest about a 35-40% drain which should get your cya down around 50-60....very manageable.

Your current CYA of 90 has rendered your chlorine very ineffective at killing algae. Once the CYA gets down to around 50 or so, you will be able to shock and clear the pool nicely.

You are going to have to lose the pucks for the remainder of the season. They will just add back CYA and you'll be back in the same old fix. Chlorinate with bleach for the rest of the season. It's the nicest thing you can do for your pool. (and your swimmers, too)

Once you make the committment to drain, it's important to read....

"How to Shock Your Pool" up in Pool School
"ABC's of Pool Water Chemistry"
"FC/CYA relationship chart"

Once you begin to shock, DON"T STOP Until your pool is crystal clear (with no sign of algae)

a) Yeah a little may "stick" but I think it's usually a matter of overestimating the amount of water which was drained or underestimating the true CYA value. Nevertheless, don't worry about.....it will make little difference to you.

b) The pucks have been driving your pH down. Your pH is fine and, once you stop using the pucks, you will be able to control the pH much easier.

Post back questions.

EDIT: Jason has eliminated all my wordiness and cut to the chase......I worked too hard on the words not to post them :lol: :lol:

 

[NCFlyersFan]

My only recommendation with the numbers you posted is to lower your CYA. Drain and refill to get this down. After that, stop using the pucks and switch to bleach. Shock the pool until you pass the overnight FC test, and enjoy your crystal clear water.

 

[austinpooldude]

Thanks folks for the quick response! I'll post back after I get the drain/refill completed.

 

[austinpooldude]

Well, I managed to drain and refill 50% of the water and the first thing I found was the PH was about 8.2. I added approximately 20 ounces of a 5-year old bottle of muriatic acid this morning, and when measured this evening the PH was down to 7.3

Here are the details:

replaced 7500 gallons (50% drain/refill)
FC 5.0
CC 0.5
PH 7.3
CYA 50
TA 70

The Pool calculator, if I've used it correctly, is suggesting I add 106 oz of Baking Soda to raise TA from 70 to 100.

While the water level was low I was able to scrub the black algea spots and make the majority fade to almost unnoticeable. But I figure I probably need to maintain a higher FC level for some time to kill it properly. The chlorine/cya chart at http://www.troublefreepool.com/pool-school/chlorine_cya_chart_shock says I need an FC of 20 which would require about 2.5 of the large 183oz chlorine jugs.

Question - I will have swimmers in the pool in 36 hours (for swim lessons), should I go ahead with the 1-time shock and expect levels to drop much lower by then? Or do I need to maintain a level of 20 ppm for awhile?

I'd appreciate guidance on what sequence to add chemicals, and whether needed. My newbie thinking is to:
a) get TA to 100
b) adjust PH to 7.6 (should be higher than it is now from the TA adjustment)
c) add a bunch of chlorine when I'm ready to shock

Question - For raising PH, if eventually needed, can I use sodium carbonate (PH Plus) from the pre-BBB days? Any harm in using it?

regards from rainy Austin

 

[Butterfly]

Question - I will have swimmers in the pool in 36 hours (for swim lessons), should I go ahead with the 1-time shock and expect levels to drop much lower by then? Or do I need to maintain a level of 20 ppm for awhile?
FC levels above minimun and below shock level for the CYA level are fine for swimmers. Be sure to read the articles in pool school that duraleigh mentioned above about shocking your pool.

I'd appreciate guidance on what sequence to add chemicals, and whether needed. My newbie thinking is to:
a) get TA to 100
b) adjust PH to 7.6 (should be higher than it is now from the TA adjustment)
c) add a bunch of chlorine when I'm ready to shock
If you are not planning on adding more trichlor, your pH and TA are just fine where they are and need no adjustment.

Welcome to the forum

 

[HBT]

The issues you were having with the zeofiber is user error. I have used cellulose fiber for over 3 years with no problems. 4 things may have caused your issues .

1) you must start with completely clean grids
2) you are using to much fiber
3) if your pool has algae it will filter it and that could explain it clogging up.
4) you cant use clarifiers/phosphate removers as they will clog up fiber instantly and can cause the problems you described.


I hope this helps you.

 

[HBT]

Oh also I forgot. I read on a website that is possible for algae to actually bloom in your filter tank. To correct this they said to use liquid chlorine (even bleach) pour directly into skimmer while filter runs until pressure decrease then backwash and recharge.