TF-100 results, 1st pool and kids want to swim!

[act]

Just bought a house with an inground vinyl pool, approx 33,000 gallons, previous owner used chlorine tablets, water looks clear. Found this sight, started reading, ordered the TF-100, and results are:

FC: 10
CC: .5
TC: 10.5
pH: below the lowest color, so <6.8
CH: 300
CYA: 95


1) So my 4 kids really want to swim...is the water safe?

2) The pool math calculator says to replace 58% of the water to get the CYA down. Will CYA come down on its own over time, or is replacing water necessary?

3) Assuming the high FC will come down over time if I'm not adding more chlorine...is that correct?

4) pH seems off, but maybe due to high FC?


Thanks for any help!

 

[jblizzle]

Welcome to TFP!!!

1. The pool is "safe" when you can clearly see the bottom and the FC is between the minimum FC level and the shock FC level for you CYA. According to the FC/CYA Chart you meet that criteria.
I would raise the pH up into the 7s for comfort though. And what is your TA? You need that to calculate how much borax to use to raise the pH.

2. Only way to lower the CYA is by replacing water ... either splash out or backwashing or pumping it out.

3. With a CYA that high, your FC is fine now and you can not ever let it drop below 7ppm ... how are YOU chlorinating?

4. Your pH is too low. When the FC > 10ppm, the pH test will read artificially high.

Have you discovered Pool School yet? Start with these:
ABCs of Water Chemistry
Recommended Pool Chemicals
How to Chlorinate Your Pool

Please add your pool details to your signature as described HERE as it will help us help you.

 

[mikech]

1) yes, though if your CYA is 95 then you are already close to being under target for FC. FC will need close monitoring after 4 kids playing about for a couple of hours!

2) Yes but slowly (though 4 kids wil help with splash out!), yes, usually replacement is the best option

3) See 1). You haven't got a high FC for the CYA currently

4) Yes, but I thought it normally read it false high

Mike

 

[Richard320]

Just bought a house with an inground vinyl pool, approx 33,000 gallons, previous owner used chlorine tablets, water looks clear. Found this sight, started reading, ordered the TF-100, and results are:

FC: 10
CC: .5
TC: 10.5
pH: below the lowest color, so <6.8
CH: 300
CYA: 95


1) So my 4 kids really want to swim...is the water safe?

2) The pool math calculator says to replace 58% of the water to get the CYA down. Will CYA come down on its own over time, or is replacing water necessary?

3) Assuming the high FC will come down over time if I'm not adding more chlorine...is that correct?

4) pH seems off, but maybe due to high FC?


Thanks for any help!

Welcome!

A steady diet of pucks will drive pH waaaaay down and drive CYA waaaay up, which seems to be the case here. What is the TA reading? You'll need to know that to calculate the dose to fix the pH.

1) The FC/CYA ratio is good. If the water is clear enough to see the bottom, after the pH gets fixed, let 'em in.

2) CYA will only come down via splashout, backwash, or draining. 95 is too high. I'd suggest you work it down slowly over a few weeks, draining maybe 4 or 6 inches at a time. I use pool water on the lawn. Just maintain the FC for whatever CYA level you end up with and things will be fine.

3) You want the high FC with your high CYA. Minimum FC should be 7. Keep it between 7 and 10 while the CYA is where it is. 7 is the minimum, 10 is the max before the pH test gets weird. It's buffered by the CYA. There's actually less bleaching power than is allowed in drinking water which is unstabilized. I took over a pool with 240 CYA and we swam at 20 FC with no ill effects. I wouldn't recommend trying it, because it's a PITA. I only did it because we were under water restrictions. It's much much easier to maintain at lower CYA levels.

4) Your pH is low because of the trichlor pucks they used to feed it. Shock powders are also acidic. High FC will mess up pH readings by making them read falsely high, not low. I'd believe that reading, and it's good that you realize it might be even lower since that's the end of the scale.

Do you have any leftover chemicals laying around from the previous owner? You need Soda Ash or pH Up - same stuff - and possibly alkalinity increaser, which is just overpriced baking soda. If not, what to buy and how to add it is here and how to use poolmath to figure quantities is here.

 

[Azgirl71]

Welcome to TFP! The others have you covered.

 

[act]

Thanks everyone for the great advice...this place is great! I have some reading and a bit of work to do but at least it's not so bad that I have to fill the pool with dirt and build a playground on top.

When I did the TA test, after adding the 2 drops of R-0007 and then 5 drops of R-0008, my water was red, not green. I never got to add drops of R-0009 to make it turn red, so no idea what the TA is. Is that possible, or should I redo the test?

I haven't added any chlorine yet. I plan on using liquid bleach when it needs it. The chlorine/CYA chart was helpful to understand I need to keep FC high with high CYA.

 

[Richard320]

If it never went green, your TA is something like 20 and your pH is down at the bottom of the 6's most likely. Just plug 6.8 pH and 40 TA into poolmath and add what it tells you to raise pH to 7.5. If you brush, it will help mix it better. Give it half an hour and recheck pH and TA and plug those numbers into NOW and target 7.5 pH again and add what it tells you. Again, half an hour to mix. Just repeat that until you see a color shift somewhere into the 7's. Then post your pH and TA readings again and someone should be along to advise you if it needs to get raised some more and if you need baking soda, too.

 

[act]

If it never went green, your TA is something like 20 and your pH is down at the bottom of the 6's most likely. Just plug 6.8 pH and 40 TA into poolmath and add what it tells you to raise pH to 7.5. If you brush, it will help mix it better. Give it half an hour and recheck pH and TA and plug those numbers into NOW and target 7.5 pH again and add what it tells you. Again, half an hour to mix. Just repeat that until you see a color shift somewhere into the 7's. Then post your pH and TA readings again and someone should be along to advise you if it needs to get raised some more and if you need baking soda, too.

Thanks so much. Heading to store now...

 

[jblizzle]

If the TA never went green, that means it may be 0 ... and your pH could be in the 4s actually.

You are going to need a lot of Borax and just keep adding and test like Richard said. Once you get a pH reading in the 7s, then retest the TA and we may need to adjust it.

FYI, I would not recommend swimming with the water that acidic.

 

[act]

If the TA never went green, that means it may be 0 ... and your pH could be in the 4s actually.

You are going to need a lot of Borax and just keep adding and test like Richard said. Once you get a pH reading in the 7s, then retest the TA and we may need to adjust it.

FYI, I would not recommend swimming with the water that acidic.

I picked up a couple boxes of the arm & hammer soda ash per the calculator. Will that work as well or should I get the borax instead?

 

[jblizzle]

The borax would raise your TA less. The soda ash will work, but might raise the TA a bit more than ideal.

 

[act]

Well after adding 4 boxes of soda ash (14 lbs) and 3 boxes of borax (14 lbs) over the last several days, my numbers are looking better, particularly pH which was very low.

FC 8.5
CC .5
TC 9.0
pH 7.2
TA 60
CYA 90

Now just want to do some gradual water replacement to get CYA down. Thank you everyone for the advice...this place is fantastic!

 

[Richard320]

Well after adding 4 boxes of soda ash (14 lbs) and 3 boxes of borax (14 lbs) over the last several days, my numbers are looking better, particularly pH which was very low.

FC 8.5
CC .5
TC 9.0
pH 7.2
TA 60
CYA 90

Now just want to do some gradual water replacement to get CYA down. Thank you everyone for the advice...this place is fantastic!

Now you're cooking! Hop in! :splash:

The testing and dosing is just going to get easier and easier and if the water isn't sparkling right now, it will be in a couple more days.