New-ish pool turning green. HELP Please!

[Adiharce]

We have had our pool since March and since May I have been struggling with the pool turning green (not swamp green, but not pretty clear water).
I tried using bleach for a week, but was having to add so much that I have gone back to chlorine tabs, which I know lead to higher levels of CYA. Would like to go back to something without the added stabilizer, but not sure what steps to take. I am new to the TFP method and would really appreciate some guidance.

Here is my info as well as I understand it.
In ground plaster pool with a spa. Sand filter.
17,000 gallons.

Numbers yesterday were:
FC: 5.0
CC: 1.0
TC: 6.0
CH 275
TA: 130
CYA:90
PH: 7.8

I added 22 oz muriatic acid per pool math instructions. 8 hrs prior to testing yesterday I added a bag of shock that we had on hand.

Today's numbers:
FC: 3
CC:1
TC 4
PH: 7.5
CH: 300
TA: 100
CYA: 100

I have small patches of green algae on the limestone steps and seat in the pool. No algae in the spa. The algae scrubs off easily with a wire brush.

Do I need to SLAM? When I read the CYA/Chlorine chart and it has shock level of 39, does that mean that my FC needs to be at 39? Is this going to be an ongoing problem due to CYA levels? Also, why is CYA level so high after only 4 months of pool operation? Can the tablets cause that much build up in 4 months. I am hesitant to drain the pool at this point as we are in drought restrictions and I believe will incur a hefty surcharge if we refill. I would appreciate any help that you can offer!

 

[RobbieH]

Your CYA is the major culprit. It has gotten so high that the lower FC of 5 is not effective. My suggestion is to drain half the water and get the CYA down before you do anything.

Your math is correct, you would need a minimum shock level of 39 to perform the SLAM process. Keep in mind, the M is for MAINTAIN. It is going to take a lot of bleach at first to maintain a minimum of 39.

Yes, tablets are the cause of the high CYA.

I don't know about your situation in San Antonio, but here they had no complaints when I refilled my pool. Draining half of your pool and refilling would take 8500 gallons, which is nothing compared to filling a 44,000 gallon pool.

 

[Butterfly]

Welcome to TFP

How did you get those test results? Do you have your own test kit? Which one?

You should not add any powders, granular, pucks type chlorine anymore for now! Use only plain bleach/liquid chlorine.

First, did you do the dilution CYA test? The CYA test will test 100 as 100 and anything above 100 also as 100 So, the dilution test will let us know about how much you need to drain. That should be the first step; scroll down to post #8, item # 9:
http://www.troublefreepool.com/threads/24188-Extended-Test-Kit-Directions

 

[Adiharce]

I purchased the TF-100 test kit.
I will perform the dilution test now and see what I get.

 

[RobbieH]

To add to what was said above, when buying bleach, make sure it's just plain bleach. Nothing scented, low slosh, outdoor, etc.

 

[Adiharce]

I completed the CYA procedure, but with the dilution and got 50. So I am thinking drain 50% of the pool. Seems so wrong for a 4 month old pool. Could the builder possibly have added too much stabilizer at set up?

Not sure what happened to my previous reply, but I have the TF-100 test kit. Just got it yesterday!

 

[RobbieH]

PB could added too much stabilizer, and if you used powdered shock products and/or any tablets, that adds to the problem. The PBs tend to really not know as much as they say they do. They added stabilizer to mine when it was complete, but they arbitrarily added about 5 lbs of stabilizer to my skimmer, which wasn't anywhere near enough to stabilize my large pool. In other words, they just know to add stabilizer, but don't know how much.

 

[Adiharce]

Thanks. Going to drain pool later today and hope for the best.

 

[RobbieH]

You are lucky your CH is 300. San Antonio water is pretty hard.

 

[Butterfly]

Once you complete the drain/refill dance, circulate the water for at least several hours before testing again.

 

[Adiharce]

Almost done draining 60% of pool. After I let water circulate a couple of hours and check chemicals do I then just start with TFP method?

 

[Kiss4aFrog]

Yes. Whatever you are thinking of adding to the pool for chemicals try to post it here first. It's so much easier having you not put it in to begin with rather than trying to counteract it later

Please add your pool info to your signature as outlined here: http://www.troublefreepool.com/content/165-getting-started

Once it's circulated and you retest ..

 

[Adiharce]

Pool finished filling and circulated.

New Numbers:
PH: 7.5
FC: 0
CH: 250
TA: 160
CYA: 35-40

Pool math indicates to add 106 oz bleach.
NOthing really indicated about TA. Is that correct?

Any other suggestions?

 

[Butterfly]

Add the bleach. Wait 30 minutes and test FC and CC and report back

yes, ignore TA for now.

- - - Updated - - -

In fact, add enough bleach to reach 10FC. That will be a nice start.

 

[Kiss4aFrog]

And during the SLAM you'll likely be over 10ppm FC and above that the pH isn't reliable so you don't need to test it until the slam is done. Save your chems !!

- - - Updated - - -

Yup, checked pool math and you'll likely be 16ppm for SLAM so don't worry about pH.

 

[Adiharce]

Updated testing:
FC: 15
CC: 0
TC: 15

Next step?

Also, can we swim with the FC that high?

 

[ranger_ric]

You can swim in water UP TO Slam level. Enjoy

 

[Daltex]

Brush often, backwash when pressure reaches 20% above normal post backwash readings, Next step is to take FC readings after dark and compare the next morning before sunrise. If the change is 1ppm or less, CC is <.5ppm, and water is clear then you can stop and let the FC drop to target level and then post results for all reading for advice on what to adjust next if anything. Read this if you haven't : SLAM LINK

 

[Abigail K]

You can swim in water UP TO Slam level. Enjoy

You can swim up to SLAM level provided you can see the bottom of the pool for safety reasons.

 

[Butterfly]

Updated testing:
FC: 15
CC: 0
TC: 15

Next step?

Also, can we swim with the FC that high?

As mentioned, you can swim up to normal shock level as long as the pool is clear enough that you can see someone on the bottom.

Is the water clear?

If yes, you can do the OCLT test tonight.