Help with Pool water balancing

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ngc4900

ngc4900

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Sep 29, 2012
82
The Villages, FL
Pool Size
14600
Surface
Plaster
Chlorine
Salt Water Generator
SWG Type
Hayward Aqua Rite (T-15)
Hi,

I have spent some time in Pool School (vinyl). I have an indoor IG 5200 GAL Endless pool (EP) that went online AUG 2012. The water has not been changed since 2012. I keep the pool at 87 degrees. I use bleach, sodium Bisulfate, and baking soda, however over last three years, I have probably shocked the pool 1 or 2 times a year with DY-CHLOR (Dura Shock). As embarrassing as it sounds, I have never measured the CYA until today since EP told me it was something I did not need to measure because the pool is indoors and obviously has no direct sunlight and it is covered when not in use.

Here are my numbers today using a new (one month old from the fractory) LaMotte ColorQ Pro-6 using Pool Math (PM):

FC: 3.1
CC: 4.0
pH: 7.4
TA: 135
CH: 172
CYA: 47
SI: -0.2
CSI: -0.07

Pool math (another software program: perfect pool software) both say I need to drain the pool and replace 36% of the water. PM also wants me to add 6 oz of CACL to increase the CH.

The water looks clear. I don't see any mustard algae.

Questions:

1. Is it necessary to drain the pool? My CYA should be 20 to 30 for an indoor pool correct?
2. Do I need to increase my FC goals (currently 2-4) to 4 - 8 which PM is showing?
3. What is a good CSI range for my pool?
4. In the future, Can I simply use bleach to do a SLAM? EP confused me since they sent a package of Di-CHOR when I first purchased the pool, therefore I have been using Di-CHOR to Shock the pool.
5. Is the Di-CLOR the reason my CYA is so high?
6. I Have no experience with Mustard Algae. Does it happen many with outdoor pools?

Sorry for the long post. Even though I have been balancing this pool for three years, I have never acquired the knowledge that I have since joining this forum and reading Pool School. :(

Thanks so much in advance,

Joe
 
Your CYA is fine. You don't need it that high for an indoor pool, but it's not harmful. In your situation, the CYA isn't so much as a UV shield but as a buffer so the chlorine doesn't destroy swimsuits and so on.

Maintain a minimum of 4 FC to go with your ~50 CYA and you'll be fine. Without the sun destroying things, I'd suggest targeting 6 and see if it stays above 4 after 24 hours. If not, target 7. Just experiment.

CSI and CH really don't matter much in a vinyl pool. You won't be leaching any Calcium from the walls if it gets too low. You could still develop scale if it gets too high, but you're a long way from that. Until it gets to +.4, ignore it.

Maintain the proper FC/CYA ratio and you may never need to SLAM the pool, ever. My pool is outdoors and stays uncovered all winter (such as it is in SoCal) and I have never developed algae in four years. If you do, then use bleach.

Dichlor is the source of the high CYA. In a pool your size, a one pound bag of dichlor will add 12 CYA Check "Effects of Adding Chemicals" down at the bottom of poolmath.
 
Why do you think you should drain the pool? The programs just offer suggestions, it is up to you to set the targets.

1) Indoor the CYA can be nearly anything, you don't need more than 20-30ppm (since that is the bottom of the recommended test kits ... which you are likely aware, the Color Q is NOT one of them, too suspect) but there is not a problem with it a little higher.

2) You need to match the FC to your CYA. See: FC/CYA Chart

3) between -0.6 and +0.6 ... not something to be generally concerned about.

4) ABSOLUTELY, use bleach!!! The Dichlor is why your CYA is a little high.

5) Yup.

6) I don't either. Why would you suspect it?

Of course, all this assume you trust the Color Q output ... I personally do not based on the things I have read on the forum.
 
Thanks so much for your help.

No, I agree, I rather not have to drain the pool. I have never followed CYA levels in the past and since my pool is small, I thought 47 would need a partial draining. Based on my CYA, a target FC of 4-7 should not cause skin/eye irritation…correct?

With respect to the mustard algae question, I sometimes do see a very faint green material that is on the floor of the pool, however it seems to come and go. It never occurs on the side of the pool. I have never had to shock the pool to make it go away.

If I ever do get this this problem, it will be a PITA as EP’s have a channel system on all four walls/floor of the pool and a water current machine both of which would have to be completely removed before I could completely scrub the pool with bleach to kill the algae.

I understand the ColorQ CYA test is not good. I have a partial color blind issue which is why I use the ColorQ for PH and titrating. As soon as I get my replacement CYA test tubes, I will use my Taylor 2006 kit and test my CYA again.

Thanks again. This site has been so helpful to me.
 
Well, spotting green on the floor would not be mustard algae. You could still follow the SLAM process to try to ensure that there is nothing living ... even if you can not scrub all the nooks and crannies.
 
Thanks again. If I did want to do a Mustard Algae Shock, Is there a kit that would read up to 28, the suggested level on Pool Math for my pool in it's current state? I don't know the range of FC for the ColorQ tester.

Joe
 
I just figured out I have a Taylor 1005. Therefore I don't have a FAS/DPD test. What a dummy I am. :(
Does TFT sell the reagents without buying the whole kit?
thanks
Joe
 

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Hi
I went ahead and performed a simple test suggested above by Richard320. Here are the results. I used a DPD test with LaMotte. My TFT FAS/DPD has NOT arrived yet. Should I simply ignore these and repeat with TFT FAS/DPD test before I suspect if there is something living in the pool and proceed with slamming the pool? Bleach quantity determined using Pool Math.


March 30/1900hrs: FC:5.4 / 23 oz 8.25% bleach added
March 31/0800hrs: FC:5.3 / 16 oz bleach added
April 01/0100hrs: FC: 6.9 / no bleach
April 01/1300hrs: FC:5.6

Thank for the help in advance.

Joe

BTW, I called a local pool guy who maintains pools and gave him my numbers in the OP. He stated my CYA was due to my TDS being to high and I needed to drain my pool, even after telling him I used Di-Chor in the past. He went on to say that I should be draining my pool every year.
 
Nothing in those results suggests a problem. But once the FAS-DPD arrives, I might raise the FC up toward shock level and Perform the Overnight Chlorine Loss Test.

For the emails, I think you want to go to "Settings" up under the Pool School button and that will show a list of your subscriptions, then just check the box and at the bottom change the notification type. You can change the default subscription type by going to "General Settings" on the left and change "Default Thread Subscription Mode:"

Personally I do not auto-subscribe to anything or get any email notifications because my inbox would be full :D
 
One last thing, LaMotte kit has a TC test. That is not same as a CC ... correct? What values is the TC? I don't remember seeing it mentioned in Pool School.. thanks
 
Pool store man was off base with that advice. Cya is not high because of TDS. It's presence adds a little to the TDS, because it is a dissolved solid. We also don't believe annual drains are a part of good pool management. It's not needed unless things are neglected, but we won't let you go down that road with the advice we give you. Things happen to create the need in many pools, but most of those are easily avoided.
 

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