Got my kit, help interpret my first test!

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pcollins22

Well-known member
Aug 7, 2016
97
Gilbert, AZ
Hi all,

I am new around here and recently received my TF-100 kit. I mainly bought this kit as I have been having trouble in the past 6 months keeping my pool clear, with a recent presence of black algae spots on a few of my steps and certain areas of the bottom of my pool (pebbletec finish). My previous kit was only testing TA, FC, pH. As of tonight, I ran a series of tests with my new kit. The results are below:

CYA = 120 (confirmed with a dilution test)
pH = 7.3
TA = 130-140
CH = 450
FC = 1.0
CC = 0.5
TC = 1.5

It was just as I figured... from reading these forums for a while I just knew my CYA would be through the roof, mainly because my previously normal "shocking" levels of liquid chlorine were not longer killing off the green ring algae around the edge of the pool, and it was staying cloudy. Also, because I have been using Trichlor pucks for over the past year of living in the house :( No idea what was being used prior to this with the previous owner.

Now is where I need some help:
  • What is my priority?
    • I would assume it is to get the CYA much lower by doing partial drains? Is this accomplished with repetitive backwashing? How much water do I have to drain out of the pool? I have a DE filter.
  • At what point do I SLAM? I have never done this method before so it will be my first. How many gallons of bleach/liquid chlorine should I buy to have on hand??
  • Question about OCLT:
    • As I am performing the OCLT to determine chlorine usage, how often do I need to be present for testing throughout the day? I am frustrated because I will be gone Friday AM until Sunday evening this week for a wedding out of state. I work M-F from 9-5 otherwise. So, should I even attempt the SLAM and OCLT within the next week, or wait until the following weekend when I have more time to be around the house?? I am wondering if I should just keep dumping in a gallon of chlorine every day or other day until then just to keep things at bay?

HELP! Thank you!
 
pcollins22 said:
Hi all,

I am new around here and recently received my TF-100 kit. I mainly bought this kit as I have been having trouble in the past 6 months keeping my pool clear, with a recent presence of black algae spots on a few of my steps and certain areas of the bottom of my pool (pebbletec finish). My previous kit was only testing TA, FC, pH. As of tonight, I ran a series of tests with my new kit. The results are below:

CYA = 100
Chlorine = 1-2ppm
pH = 7.3
TA = 130-140

It was just as I figured... from reading these forums for a while I just knew my CYA would be through the roof, mainly because my previously normal "shocking" levels of liquid chlorine were not longer killing off the green ring algae around the edge of the pool, and it was staying cloudy. Also, because I have been using Trichlor pucks for over the past year of living in the house :( No idea what was being used prior to this with the previous owner.

Now is where I need some help:
  • What is my priority?
    • I would assume it is to get the CYA much lower by doing partial drains? Is this accomplished with repetitive backwashing? How much water do I have to drain out of the pool? I have a DE filter.
  • At what point do I SLAM? I have never done this method before so it will be my first. How many gallons of bleach/liquid chlorine should I buy to have on hand??
  • Question about OCLT:
    • As I am performing the OCLT to determine chlorine usage, how often do I need to be present for testing throughout the day? I am frustrated because I will be gone Friday AM until Sunday evening this week for a wedding out of state. I work M-F from 9-5 otherwise. So, should I even attempt the SLAM and OCLT within the next week, or wait until the following weekend when I have more time to be around the house?? I am wondering if I should just keep dumping in a gallon of chlorine every day or other day until then just to keep things at bay?

HELP! Thank you!
Click to expand...

You need to get your CYA down. If partial drain / refill is an option then start from there. Your CYA test result is out of range, it could be any number above 100. I'd recommend to dilute your pool water sample with tap water 1:1 run the test again and multiply it by 2. If it still 200 after that then I'd try 1:2 dilution. This would give you an idea what are you dealing with.

Your current FC level is practically non existent. I wonder if the pool is green at the moment. If it's not then it's interesting what keeps algae at bay- are you using any algaecides?

Switch to liquid chlorine (bleach) for chlorination purposes immediately or you'll never get this under control.
 
I was using Trichlor pucks for chlorine until about 1 week ago when I found this site - because I was searching for an answer to my black algae problem.

I dumped in 2 gallons of 10% Liquid chlorine on day "0", and then have added another gallon each day or every other day since. I have just been trying to keep something in the pool to counteract more algae, until I received my test kit to get my readings.

Remarkably, my pool is overall pretty clear right now. If you came over and weren't a "pool guy" you would have no idea that anything was going on unless you saw the black algae spots on the steps. I did use a few ounces of Algaecide (Skill It) about 2 weeks ago to combat the black algae spots, but it hasn't made much of a difference (not surprising and after reading these forums I likely won't use it again).

I need to get better with brushing the surface each day, but am doing it roughly every 3 days or so. Again, mainly waiting to get my readings so I could get some guidance from you all here before I proceed.
 
Do the CYA dilution as Max suggested. Familiarize yourself with: Pool School - PoolMath

Before we talk too much more about slamming, we need to see what your CYA is. PoolMath will help you determine how much water you need to replace to get the CYA to a decent level.

The OCLT is a check to see how much FC is being consumed by gunk without the interference from UV. It's not really a test of "chlorine usage", but perhaps that is just a semantics issue.

Slamming requires attention and can't be done while no one is around to help with chlorine additions. We can help guide you with your schedule, but for now, CYA is your top priority. Then brushing the algae several times a day and adding a jug of chlorine daily.

- - - Updated - - -

Sorry. I meant to include this link but pressed submit too early...:
Pool School - Black Algae
 
max2k said:
You need to get your CYA down. If partial drain / refill is an option then start from there. Your CYA test result is out of range, it could be any number above 100. I'd recommend to dilute your pool water sample with tap water 1:1 run the test again and multiply it by 2. If it still 200 after that then I'd try 1:2 dilution. This would give you an idea what are you dealing with.
Click to expand...
I did this 1:1 dilution with tap water + pool water and ran my CYA test again.

Black dot disappeared at "60" on the CYA view finder tube, which should then correspond with a true CYA of 120, correct?

Is the next step to do a partial drain?

When I put 120 into Pool Math, it tells me I need to drain 67% of my water to reach a goal of 40 for CYA.
 
In your case, I would first confirm that you have black algae with the fingernail test.

If it is positive, you need to maintain between target FC level and shock level FC.

You don't have to do a full-blown slam if you have black algae. Therefore, you would not need to take your CYA down to 40. In Gilbert, maybe 60-70 would be a good place for your drain goal.

If the test comes out negative, try an OCLT: Pool School - Perform the Overnight FC Loss Test (OCLT)
 
Thanks Marian.

As another update, I just ran a gamut of samples for other areas, and here are my cumulative findings:

CYA = 120 (confirmed with a dilution test)
pH = 7.3
TA = 130-140
CH = 450
FC = 1.0
CC = 0.5
TC = 1.5

Again, pool is overall clear, other than the black spots which I will try to confirm is black algae, in addition to a present/disappearing green "ring" around the water edge depending on how much chlorine I have in the pool. It is currently not present.

And, just to confirm, should I be partial draining or adding significant amounts of chlorine first?

Sounds like irregardless I need to do a partial drain (looks like 45-50% drain based on pool math) to drop CYA near 60-70. And after that is completed, THEN if I do indeed have black algae that's when I add my liquid chlorine to between Target and Shock FC levels? Pool Math is telling me this would be a FC of between 15-47, which will obviously be different if I first do the drain. Just trying to make sure I dont dump in all this chlorine just for it to be drained out and wasted.
 
pcollins22 said:
I did this 1:1 dilution with tap water + pool water and ran my CYA test again.

Black dot disappeared at "60" on the CYA view finder tube, which should then correspond with a true CYA of 120, correct?

Is the next step to do a partial drain?

When I put 120 into Pool Math, it tells me I need to drain 67% of my water to reach a goal of 40 for CYA.
Click to expand...

What Marian said ^^^ + please bring your FC up to 12-14 ppm using bleach ASAP: even if you're going to drain soon you're going to waste 1 gal of bleach tops but it will keep your current water sanitized and slow down / stop algae growth. For your size of the pool it's 2 gal of bleach. You can start OCLT test about 1 hr after adding bleach with pump running so it would have good chance to mix evenly.

Just read your latest post- if you're adding 1 gal of bleach / day for your pool it is equivalent to at least 6 ppm FC. At your CYA level you shouldn't be losing more than 2 ppm a day to the Sun so if you're at 1 now you still have 3 ppm unaccounted for, usually algae killing process consumes FC this way. For reference I lose 1.5 ppm on the hottest day here in CA with CYA = 40.
 

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Morning update of OCLT:

Base FC: 28ppm (taken at 9:30pm, 40 minutes after liquid addition)

Morning FC: 19ppm (taken at 6AM, no direct sunlight)

Pool still looks very clear.

What is my next step? Looks like I do indeed need a SLAM, but should the partial drain (about 50%) be done first? Can I do this all at one time through the backwash outflow, and then re-fill with the hose afterwards?

- - - Updated - - -

Pictures are attached to both show clarity and pool setup, and also to show the small black patches I have on the steps. Hope you can make them out.
IMG_1872.jpgIMG_1873.jpg
 
Yes, in Gilbert you should be able to drain and then refill without worrying about the water table and your plan sounds good. Then let it mix well, get your new CYA, and add chlorine. You may need to do a regular slam first as that was a lot of loss last night.
 
Thanks for the advice.

Now my last dilemma I posted previously:

I work Wed/Thurs from 9-5pm. I leave town early Friday AM and won't return until Sunday PM as I am out of town for a wedding. I work M-F 9-5pm next week. Wont have any "free days" to be at home the majority of the day until the following weekend.

Do you recommend I do this partial drain and fill before I leave this weekend, and then wait to SLAM the following weekend when I can be around for the full day? I was thinking I could just keep a gallon of bleach in the pool every day or other day between now and then. I would hate to waste that $$ but I also don't want to mess up the SLAM.

Thoughts?
 
IMO... If it were my pool, and I had time, I would drain and refill now. The algae will wait for you to get back either way.... and will just get worse. If your CYA is lower, whatever bleach you, (or a friend/neighbor), add will have more impact.
 
pcollins22 said:
Thanks for the advice.

Now my last dilemma I posted previously:

I work Wed/Thurs from 9-5pm. I leave town early Friday AM and won't return until Sunday PM as I am out of town for a wedding. I work M-F 9-5pm next week. Wont have any "free days" to be at home the majority of the day until the following weekend.

Do you recommend I do this partial drain and fill before I leave this weekend, and then wait to SLAM the following weekend when I can be around for the full day? I was thinking I could just keep a gallon of bleach in the pool every day or other day between now and then. I would hate to waste that $$ but I also don't want to mess up the SLAM.

Thoughts?
Click to expand...

If it were my pool, I would wait on the drain...do what needs now as far getting your chlorine up or a SLAM or whatever even though with high CYA you will need more chlorine, take care of the black algae now....with the AZ sun & heat I would drain 100% this fall or winter, do an acid wash (that ring around your pool is scale), kill 3 birds with a fresh fill......the CYA, the CH, the Scale
 
oldguy70 said:
If it were my pool, I would wait on the drain...do what needs now as far getting your chlorine up or a SLAM or whatever even though with high CYA you will need more chlorine, take care of the black algae now....with the AZ sun & heat I would drain 100% this fall or winter, do an acid wash (that ring around your pool is scale), kill 3 birds with a fresh fill......the CYA, the CH, the Scale
Click to expand...

could you please clarify reasoning on waiting for drain? I understand 100% drain solves everything but then why wait if going this way?

IMO Marian's recommendation is less drastic and OP can always drain the rest later when feeling more confident on the proposed acid wash. I'd agree with her and take things slower- it would solve immediate algae bloom coming, drop CYA & CH to more reasonable levels and let OP enjoy the pool sooner as doing SLAM at lower CYA levels is comparatively easier.

In terms of fighting CH / scale my pool for example, has CH = 500 right now and it's been 1.5 years that way and it's going to be for at least one more year. I got scale along with the pool and it seems getting lighter with lower pH I'm trying to maintain (7.3 - 7.4). From my point of view scale is order of magnitude less of a problem than algae.
 
After thinking about it more, I am planning on doing a partial drain tomorrow while I have a slow day at work, then re-filling as quickly as possible, re-testing my water tomorrow night, and starting my SLAM whenever I can get out to buy enough bleach to have on-hand to maintain FC shock levels.
 

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