First real test results re: water balance

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Vince-1961

Well-known member
Jul 1, 2014
242
St. Simons Island, GA
I just received the Taylor k-2006 test kit for a 12,500 gallon above ground, vinyl pool with SWG generator. Water is clear and beautiful. Not burning my eyes anymore. Test was performed at 9 AM when the SWG had been off for 16 hours. I'm concerned about water balance at the moment, not chlorine.

pH 7.6
Calcium hardness 120 ppm
total alkalinity 130 ppm
CYA 32
FC 1.5
combined chlorine 0 (but I used the smaller sample amount instead of the larger, more accurate amount & am not concerned about chlorine just now)

According to the test kit wheel, the saturation index is -0.1.

According to test kit booklet, I'm thinking I need to add a gallon of muriatic acid to bring total alkalinity down to about 80.

The booklet says 120 ppm calcium hardness is low, but TFP recommends 0-300 for a vinyl pool, so there's a conflict between the two recommendations.

I'll have to go purchase more CYA as I'm out. I am, however, surprised it is so low since I originally put in more than was called for but that was 4 weeks ago.

What's your opinion on these first test results?
 
You have a vinyl pool, so you can safely ignore CH. It is only a problem with vinyl if it's way too high.

I think you can ignore TA unless it's causing problems with wild swings in pH (your pH as it stands is fine). This is certainly one of the last things to be worried about.

Your CYA is low for a SWG, but you know that already.

I've also heard others say that the smaller sample size for chlorine is plenty accurate. I always use the smaller sample.

I hope you mean you're not worried about the FC because you're already addressing that, because I sure would be worried about FC at 1.5.

I also ignore the test booklet and use Pool Math instead. Have you discovered that gem yet? If not, check it out. Really easy to use.
 
Well my first opinion is that you SHOULD be worried about your chlorine level right now. It's 1.5. That's too low. Why not bring it up to avoid possibility of an algae bloom.

Your TA is a little high, but I wouldn't worry too much about that unless the pH rises. If it does, lower it with acid, and that will lower TA as well. If it rises again, lower it, and eventually your TA will find the sweet spot. If you choose to lower the TA with acid you will be lowering your pH as well. You could bring pH down to 7.3 or thereabouts, but don't bring your TA right down to 80 now, as you pH will be far too low.

Yes, your CYA needs to be increased. Try a target of 70 first. Don't target 80 as you might overshoot.

I think your calcium hardness is fine where it is, but others here with more knowledge may have a better opinion.

EDIT: I see Smeade beat me to it. :)
 
What he said ^^

Don't add a gallon of acid to lower TA. It will drop your pH too low. Check out Effects of Adding Chemicals down near the bottom of poolmath. You won't damage plaster, but you might damage the pump and you can say hello to burning eyes again.

How many times did you test the CYA? Even after several years practice, I pour it back and forth again and again until I'm sure of what I'm seeing. Being off 10 or 15 is normal, but if you targeted 70 and you're reading near 30, something is going on there. Could be test error, could be some bad CYA from China, and the liquid stuff doesn't seem to give the results it should, based on reports this year.
 
Thank you for the replies. Since the water is clear and beautiful, I really didn't want to be making any big adjustments, especially since I was worried about changing the pH too much by adding acid.

What I meant by not being worried about chlorine at the moment is two fold: 1) I was more interested in water balance, and 2) this morning before some regular maintenance, the skimmer was clogged, so the pump wasn't doing much and there was white crust all over the SWG electrolytic cell, so I figured the chlorine would be low. Now that it's running normally again, I'll test for chlorine when I get home after it's been running all day and get truer results.

PS- the SWG has been in use for about a month now. Is that a normal time frame for the electrolytic cell to get completely covered in a white crusty paste? (It came right off with just a garden hose.)

PPS - I tested CYA only once. It seemed like an easy and straightforward test, but I'll do it again before I add more CYA just to be safe.
 
I got home. Added CYA and an extra strong koi pond pump to circulate water much faster. Let it run for about an hour and then brushed CYA around until it was no longer visible on bottom of pool. Test results now are:

FC still 1.5
TA still 130
pH down to 7.5 (from 7.6)
cc still 0
CYA up to 50-ish.
did not test for calcium hardness.

So, I added a wee bit more CYA (I do not have a reliable method of weighing such small amounts) and a gallon of bleach. Will leave regular pump and extra koi pond pump running overnight as I realize that CYA takes time to dissolve fully.

PS- I did not buy the AquaChem brand of CYA on shelves at Lowe's, Home Depot & Wal-Mart as it said "made in China." I bought the My Salt Pool brand off the shelf at Wal-Mart b/c it said "made in USA."
 
Your CYA addition can take up to a week to fully register on a test ! Let's hope you didn't over shoot.
I would not recommend broadcasting it into the pool. You should put the CYA in a sock or knee high and put it in the skimmer basket if you have one. If you don't have a skimmer hang it in front of the return. Pump should be running the whole time until it is dissolved with either method. ?
 

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According to Pool Math, the addition of a gallon of bleach yesterday evening should have raised FC well above 3. Because FC was at 3 this morning, I am going to assume that a lot more than just 1 ppm got consumed overnight. Plus, both my wife and I thought the water looked clearer this morning and the paper filter was brown even though it was white after being cleaned yesterday.

Therefore, I conclude I must have algae. I added another gallon of bleach just now (it's all I had on hand), will let SWG run on "boost" all day. I'll buy lots of bleach today and make a decision whether to SLAM the pool when I get home and test it again to see where CYA and FC levels are.

Recommendations?
 
I believe your CL level was too low for too long. I think you're getting caught up in TA and pH and CYA, and less concerned about the most important one - chlorine. In a couple of posts above you stated (in 2 separate posts) that CL was 1.5, but you were worried about the CYA level. You MUST keep your chlorine level up, first and foremost. Then you can focus on your other levels. Yes, you have algae in my opinion. Do NOT add any more CYA because you are probably going to have to SLAM. Also, as someone else already stated, your CYA may not show up on a test for a week. So try to add up what you've added and use pool math to determine your current CYA level. And then refer to the CYA chart to see what your CL level needs to be.
 
SURPRISE! I expected my FC to be the same as this morning when I got home and tested it, b/c I figured between the sun and whatever is in my pool (algae?) the gallon of bleach I put in this morning would have been consumed. I just tested it .... twice .... and it came back at 9.5 and 10! Now I am wondering whether I need to SLAM it. (I bought lots of bleach today in anticipation of slamming tonight.)

Should I or shouldn't I?
 
Good morning everyone! I must have pushed the wrong button on the pump so it was on timer and turned off sometime in the middle of the night. So, I performed 2 FC tests, one on the still water and a second after the water was well circulated by pumps. First one on still water = 51 drops (FC 25.5). 2nd one on moving water = 54 drops (FC 27).

Someone please tell me what to do next. :confused:
 
Thank you for the advice re: pump, Pwrstrk. Didn't know that. 3rd test of the morning came back at 52 drops or FC 26, so I reckon that means it passes. So, now I wait for another 5 days for the CYA to dissolve fully and get a proper test reading and just go back to the regular pump with SWG for 8 hours per day while I wait? (8 hours is 1 turnover of pool's volume.)
 
You can let the FC drift down to normal FC levels for the CYA level. Then run the SWG.
However long the pump needs to run to maintain FC levels. Doesn't mean you have to turn the water over once. Whatever it takes to keep FC in range. ?
 

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