pool is green

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taz101

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Aug 21, 2010
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Hi all,
I have a problem I can not fix. I have had this pool for 5 years and no problem. New SWG in Dec. It is green. I took a sample to the local pool store and they tested the water and said TA was low and sold me 4kg of sodium bicarbonate to put in over 4 days. The ph was 7. Over the past month I have shocked and added over 40 lbs. of 90% chlorine. I have added 30 lbs of sodium carbonate. I bought a Taylor K2006 test and this is the results this morning.

FC 0.2 CC .8 ph 7 TA 130, 125 using 10ml test Base demand test 22 drops = 7.8 (= 26.6 lbs of sodium carbonate for a 25000 gallon pool CYA 1.6 on the side scale or 3/8” of solution.
I am lost. Any suggestions?
Thanks
Paul
 
WRT to the CYA level, the scale you are using is unfamiliar to and likely most others. If you can translate that into PPM, it would help.

Algae needs to be vacuumed out.

What are you using to test the water?

What form of chlorine did you use?

Have you read the Pool School section? That will give us a common base to work from.

Where are you located?

Scott
 
Paul,

Welcome to TFP. I hate to say this, but your pool may be over stabilized. Tough to say since CYA at 1.6 is not a good measurement. CYA is typically measured in increments of 10ppm and I'm guessing yours is pretty high, using powdered chlorine (unless it was calhypo?). It sounds like you need to shock. Shocking is a process, not a product, and you need to continue that process until the pool clears. That said, if you pool does in fact have high CYA levels, you will need to bring that down via a partial drain and fill 1st. Then go through the shocking process. Take a read through pool school, button on upper right of this page...and the specifically the articles below, and let us know if you still need help.

pool-school/defeating_algae

pool-school/shocking_your_pool

turning-your-green-swamp-back-into-a-sparking-oasis-t4147.html

Detrmining your CYA level, establishes what your "shock level" FC is...you then have to hold your FC at that level, filtering 24/7, until the pool clears.

Here is the CYA/FC relationship chart

pool-school/chlorine_cya_chart_shock

Hope this helps :goodjob:
 
We can help you clear all of this up :)

The first thing to do is to get reliable test results. You have made a great start on that by getting the K2006. Now we just need to clear up a few things before we can give you specific directions on what to do.

What kind of chlorine were you using to shock? Can you tell us the brand name or better the chemical name of what you used?

CYA should be a multiple of 10 between 10 and 100, you are probably reading it on the wrong scale. Look for the scale that has numbers like 30, 40, 50, 60, 80, 100, and tell us what your reading is on that scale.

PH at 7.0 is a little low, but not a huge problem. Your TA is a little high, which will tend to bring the PH up over time. The pool store suggestion to add sodium bicarbonate wasn't a great idea, but it won't cause too much trouble. TA around 130 is too high for a SWG, but this is secondary, not really a factor in your algae problem.

The key to fighting algae is to hit it hard and focus on eliminating all of it before slowing down. You can add lots and lots of chlorine slowly over a period of time and never eliminate the algae. You should do some background reading at Pool School, especially the article on fighting algae, while you are figuring out your CYA level. You don't want to start fighting the algae until you are sure of your CYA level.
 
CYA test when I did it and the pool store when doing the CTA the black dot disappeared before the solution was 1/3 to 1/2 the way to the 100ppm mark. On the outside of that chamber there is a mark 1.8 it was not quite to there. The chlorine I buy is triclor 90% and the is all that is available here and is sold in bulk with no label. Probably from China.
I read in the pool school last week but can not find my solution.
I put 20 lbs. of chlorine in last week the algae died (turned brown) and I was vacuuming to waste. 3 days it is green again. I have never had problems in 5 years.
The guy at the pool store said the TA was low which my test showed 80 ppm. It is hard to get good info or help here in Costa Rica. Try this try that etc.
I will keep reading the pool school.
Thanks
For your help.
 
Trichlor adds chlorine and CYA and also lowers the PH. Since you have used so much trichlor recently, your CYA level has gotten to be very high, probably well over 100. You can get a better idea of just how high by doing the CYA test again, but this time mix equal parts of pool water and tap water together, do the CYA test on that, and then multiply the result by two.

You need to get your CYA level down to something more reasonable, preferably down to somewhere around 70 or lower. Until you do that it will be very very difficult to kill all of the algae.

When using trichlor as your primary chlorine source it is a good idea to keep TA around 120-130. But when using a SWG as your primary chlorine source it is much better to aim for a lower TA level, around 60 to 70. With a SWG, TA levels above 70 tend to cause the PH to rise, sometimes quite quickly, which can get annoying. There is no real harm to having TA higher than ideal as long as you keep the PH in range.
 
Roughly 70% of the water needs to be replaced. Also if this is a vinyl pool, you should not drain more than 12-16" at a time...if plaster and you have no water table issues, you may be able to be more aggresive with the drain and fill.

CYA at 210 is really high, you are looking for it to be in the 70ppm range using a swg.
 
Assuming your water table in the ground is below that point in the pool, yes and you will need to do that twice. That should get your CYA level down to about 25 or so, a much easier number to work with.

Do you have access to a supply of laundry bleach? Here is the US, it's usually either 5 or 6 percent sodium hypochlorite. The rest is salt water and perhaps a little lye that will raise your pH. Bi-Sulfate or Muriatic acid (MA) will be your friend then as they lower a pool's pH.

When rain has diluted the pool, you can add some of the tri-chlor powder/tablets to re-elevate the CYA level then switch to bleach or a salt cell for your chlorine.

Scott
 

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Why will I have to do it twice?

PoolGuyNJ said:
Assuming your water table in the ground is below that point in the pool, yes and you will need to do that twice. That should get your CYA level down to about 25 or so, a much easier number to work with.

Do you have access to a supply of laundry bleach? Here is the US, it's usually either 5 or 6 percent sodium hypochlorite. The rest is salt water and perhaps a little lye that will raise your pH. Bi-Sulfate or Muriatic acid (MA) will be your friend then as they lower a pool's pH.

When rain has diluted the pool, you can add some of the tri-chlor powder/tablets to re-elevate the CYA level then switch to bleach or a salt cell for your chlorine.

Scott
Click to expand...
 
Drained and filled the pool. Drained all but 4" of water. Killed algae with bleach. Test results this morning

FC/CC 0 PPM
PH 7.2 added 2 drops of r0006 so it should need 1lb 5.5 oz of soda Carb. to bring it to 7.6 25000 gal
TA 160 ppm
CYA 0 PPM Is it safe now to use trichloro to shock and then let the SWG take over?
Thanks
for all the help
Paul
 

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Yes, shocking with trichlor is alright as long as you are careful to not use too much. Trichlor will raise both FC and CYA and lower PH. You don't want to use more than 20 lbs of trichlor total, or CYA will get too high again. That is quite a lot, so I don't believe there will be a problem. Other than that, you need to keep an eye on the PH when using large quantities of trichlor.

Your TA level is fairly high and adding sodium carbonate will raise it higher. Since you will be using trichlor for a little while you do need to raise the PH, but you don't want to raise the TA level any more than you have to. If you can fine borax/sodium tetraborate decahydrate/sodium tetraborate pentahydrate that would be a better way to raise the PH, as it won't raise the TA nearly as much. If none of those are available, then sodium carbonate will do.
 
UP Date Things were looking good. I had 12 bags of salt on hand but that only brought my salt level to 2000. Now there is no salt to be found here maybe for a month. My ph and everything is fine but I have to add chlorine. I added 10 gal 0f 3.5 clorox but that only lasted for 1 day at a cost of $44.
I am scared to add tri-chloro but may not have a choice. The question I have is our rainy season starts in May and there will be a lot of water exchange in the pool through Oct. Should that dilute the CYA? I need to add something it is looking green.
Thanks Again for all the help.
Paul
 
Paul,

At the risk of offending you, I am going to say you need to stop all your treatments and start reading Pool School. Reading through your posts, it doesn't seem like you yet have a good grasp of the function of chlorine, CYA, etc and how to manage them in your pool.

Start with the basic articles like "ABC's of Pool Water Chemistry" and re-read them if necessary.

BBB only works if you test accurately (which you seem to be doing) but THEN understand what the tests mean and what to do about them.

Lots of us here will help you every step of the way but you have to acquire the knowledge to make it all fit together for you.

PS - I hope you can find something other than tri-chlor to shock. Liquid chlorine is always the best and, in my opinion, tri-chlor is the most troublesome. That is also a beautifully tiled pool......very handsome!
 
What is your CYA currently? When you run an SWCG your CYA should be around 70. You can use the pool calculator to see how much trichlor you can use before your pool gets to 70 CYA. Check the "effects of adding chemicals" section near the bottom of the page. How many inches of rain is typical for your rainy season? You may want to stock up on extra salt when you can and keep about 4 jugs of bleach on hand for the rainy season. You may also want to consider adding 50ppm of borates to the water to help retard algae growth. Adding borates is a 1 time deal until the excessive rains dilute it away.

Since you do get a lot of rain at times, check and see if there is any calcium hypochlorite (cal-hypo) based shock available. It will raise calcium, but does not contain CYA. Are you able to have chemicals shipped to you or is it cost prohibitive?
 
Hi Dave and zea3,
I am not offended at all I just don't want to mess up. I have been reading the Pool School and understand what my readings should be but thay are all over the place and here in Costa Rica (by the way we lived in Whitsett,NC for 35 years before moving here) there is so littler available. We can get tri-chloro tabs or granular, flocculant, sodium carb and bicarb and that is about it. No shock at all. I have added 3.5 pounds of tri-chloro in the past week and 1 gallon of muriatic acid because the ph was 8. this was 3 days ago and here are yesterdays readings.

FC 22.5
CC 0
PH 7.0 added 10 drops of R-0006
TA 350 ppm
Cal. Hardness 150 PPM
CYA 30 PPM this went up 30 with 3.5 lbs. of tri-chloro

As you see the readings are crazy.
Thanks for your help
Paul
 
Hi Paul, you can let the FC come down on its own. Don't worry about the TA unless you are constantly having to lower the pH. The CH needs to come up to 250. See if you can find any cal-hypo granular chlorine or calcium chloride/calcium dichloride. Is it possible to order online and have items shipped to where you can pick them up?
 

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