New Pool is unstable pH, CYA?

[ThisGuy3675]

Hello,

I just had a new inground plaster pool put in and filled in February. I am trying to do all of the chemistry myself, but man, it goes everywhere. I have been slowly upping my CH and TA (currently CH=220 and TA=150). I have been adding pH reducer but I may not be adding enough. I don't want to etch my walls. But correct me if I'm wrong, the first 6 months of a plaster pool is a uphill pH battle (constantly increasing) pulling pH from the plaster. I can't even measure my pH its so high. I did an acid base test and it needed 6 more drops to get it down to 7.6 SU. (Taylor kit). Am I going about this right? Slow and go I always thought, better a little high than a little low for pH. The water temp is only 68 right now and the water is crystal clear.

Not only that, but my CYA is high. I have an inline chlorine tab drip (adjustable). It had been at a 3 but today I cranked it down a little more to 2. My CYA was just measured at 55ppm, which is elevated. My FC on the pH strip said I had almost no FC, but I put enough in to raise it 1ppm and now its telling me I'm at 3.5ppm FC. I have no measureable CC at this time. No idea why the CYA is high. I think the pool guys who first came initially added way too much. That is the only way I can account for that. It seems to me dissolving trichlor tabs slowly would not add that much.

I use test strips every other day for quick testing and the full testing every week. Am I doing this right? Too high pH and CYA?

I'm new, so be gentle. I understand the chemistry for the most part, I just need help understanding the interactions better. Thanks.

Chris

 

[kimkats]

Hi!!! I am SOOOO glad to see you have a good test kit. Now I have a job for you. Ready? Go get your test strips. I will wait for you......got them? Now walk over to the trash can and put them in there. Ahhh I feel much better now :slidehalo:

They do more harm than good as you just think your water is good. There is reason we call them "guess strips".

Now look down at my siggy below for pool math. Use it to see how much muratic acid to add to get your PH down to 7.8 add the acid and let the mix for about 15 mins and retest. Keep doing this until you get a solid 7.8 for PH.

Come back and let us know when this happens and we can go from there.

Kim

 

[duraleigh]

If you haven't already, please follow Kim's good advice.

Now, being gentle as possible, No, you do not yet have a good handle on the chemistry.....not at all.

We'll help you get there but you got some "learnin'" to do.

Please read the ABC's of Pool Water Chemistry in Pool School. You'll find CYA is just fine, CH is not bad and TA is too high.

More to come but start with us by posting your chem results like this...

pH
TA
FC
CC
CYA

Take those tests with the K-2006....nothing else.

 

[woodyp]

TA is already too high at 150 btw.

 

[ThisGuy3675]

Hi!!! I am SOOOO glad to see you have a good test kit. Now I have a job for you. Ready? Go get your test strips. I will wait for you......got them? Now walk over to the trash can and put them in there. Ahhh I feel much better now :slidehalo:

They do more harm than good as you just think your water is good. There is reason we call them "guess strips".

Now look down at my siggy below for pool math. Use it to see how much muratic acid to add to get your PH down to 7.8 add the acid and let the mix for about 15 mins and retest. Keep doing this until you get a solid 7.8 for PH.

Come back and let us know when this happens and we can go from there.

Kim

So last night, I added some more dry acid to bring the pH down. It wasn't enough, so I went to the chem store in town and got muratic acid. (I had also added some Calcium to bring it up some as well).
Last night
pH=7.9 (Acid demand test 1 drop from 7.8)
TA=130
FC=1.6
CC=0.2
CYA=55
CH=220
This morning
pH=7.8
TA=110
FC=1.0
CC=0.2
CYA=55 (not tested again)
CH=250

Bringing the pH down appear to have gotten the TA back in line. I am a little surprised at the FC drop. The TFP recommended levels say CYA between 30-50. That is why I brought it up as a concern. The Chlorine CYA chart indicates that I bring the FC up to 6-8. I also have an ozone system in the pool and I am unsure of how this precisely effects the chemistry. I understand it helps displace the O2 in the water thereby reducing DO demand for algae.

 

[kimkats]

The drop in the FC could be from it being used up doing it's job. We will keep an eye on it.

Don't bother testing CYA again for a little while. It is good where it is for now. It is getting into the hot time of year so a CYA of 60 (we round round up) will not be a bad thing. You do not really want it any higher though.

Lets work on the TA some. Bring the PH down to 7.2 each time it goes up to 7.8. In doing so you will lower the TA a little bit each time.

The ozone system does little to nothing to the chemistry of an outdoor pool. You get plenty of ozone from the sun. It ONLY works on the water that passes through it and that is very short lived. If only it did what the box says it does

Now get your FC up and keep it up to your CYA level as shown on the chart. We do not want any green monster showing up!

I find I have to add about 3 ppm of FC each day. Right now that is just about a gal of 12% chlorine each evening. Different areas have different needs. You will learn what your pool likes over time.

Kim

 

[pooldv]

CYA at 55 or 60 isn't really a big deal. You will lose a few ppm of CYA every month. Just keep FC level at target for your CYA, round up to the next 10, [FC/CYA][/FC/CYA].

 

[ThisGuy3675]

Uh-oh. Something went haywire. I put in the MA let it mix and then the bleach for the FC. According to pool math, I needed 2+ quarts to increase the FC level from 1 ppm to 5ppm. After testing, I had to dilute the FC test for it to read. I calculated about 25ppm FC!!! Like I am SLAMing the pool. What in the heck? I won't be able to get a decent pH reading until the FC comes back down. I tried the alkalinity test which actually turned the reagent blue-yellow instead of green red. They said it is high FC that will cause that. Alkalinity ended back up around 110ppm according to that test, but I will have to wait for the FC to dissipate. Dang.

pH=???
TA=110ppm
FC=25ppm!!!

Ug. Is there anything at this time I need to worry about? Or should I just wait it out and keep my system circulating (or let it sit). Very likely my bad.

 

[Texas Splash]

It takes just over 4 gallons of 8.25% bleach to go from zero to 25 ppm in a pool your size. You had an FC of 1 earlier, so I can't imagine you put that much bleach in the water. Perhaps a testing error? Are you using the 10ML sample as follows:

10 ML sample, ONE heaping scoop of powder & mix. Count drops from pink to clear. Take that result and divide by 2. Example: 14 drops = FC of 7.

Since your CYA is rounded-up to 60, a safe SLAM FC level is 24, so you are still okay. If you are not actively doing a SLAM, then it will take a couple days or so for the FC level to fall on its own. If it truly is that high, then it was either high before you added the 2 quarts and/or the % strength of bleach is much stronger than you thought.. Remember on the calculator you have to manually type-in the correct "weight" (%) of the bleach you are using.

 

[Nursenini]

Welcome to TFP!! You are in the RIGHT PLACE for sure!! The experts here will have you testing and balancing like a pro in no time. Read and REREAD the ABCs and the other Pool School articles while waiting for your FC to drop. Don't stress too much, you won't ruin your pool overnight. I should know...I have made similar "oopsies" with my chlorine and testing...

 

[ThisGuy3675]

It takes just over 4 gallons of 8.25% bleach to go from zero to 25 ppm in a pool your size. You had an FC of 1 earlier, so I can't imagine you put that much bleach in the water. Perhaps a testing error? Are you using the 10ML sample as follows:

Since your CYA is rounded-up to 60, a safe SLAM FC level is 24, so you are still okay. If you are not actively doing a SLAM, then it will take a couple days or so for the FC level to fall on its own. If it truly is that high, then it was either high before you added the 2 quarts and/or the % strength of bleach is much stronger than you thought.. Remember on the calculator you have to manually type-in the correct "weight" (%) of the bleach you are using.

I had diluted the sample but I just did a retest... I figured out that I had done the test using a measuring container that I use for bleach, et al. It must have retained some. #newbie

pH=7.0SU
TA=100ppm
FC=6ppm

The pH dropped a little more than calculated. So at this point do I aerate to bring the pH up without adding alkalinity? Like using the waterfall?

Again, thanks all for your help folks. It is more than appreciated.

 

[duraleigh]

So at this point do I aerate to bring the pH up without adding alkalinity? Like using the waterfall?

I would leave it. pH will rise on it's own so it's safe at 7.0 (but no lower) and should climb a bit. What does SU mean (after the pH)

 

[ThisGuy3675]

I would leave it. pH will rise on it's own so it's safe at 7.0 (but no lower) and should climb a bit. What does SU mean (after the pH)

pH units are read in Standard Units (has to do with electric potential and hydrogen potential in natural waters). From my background in Hydrogeology and Geochemistry. Used to writing it in reports. :study:

 

[kimkats]

LOL I have SO been there, done that! I have a bottle that is used for collecting water only now!

Glad it is going good again!

Kim

 

[ThisGuy3675]

LOL I have SO been there, done that! I have a bottle that is used for collecting water only now!

Glad it is going good again!

Kim

Thanks, Kim. I have a dedicate bottle as well (now). So at this time I don't have to worry about the TA? Is that correct? I have read some of the threads regarding using borates to stabilize pH and reduce chlorine usage. Would you recommend this at this time or wait until the pool really stabilizes after several months?

 

[kimkats]

Lets wait about 3 months or so. That allows you to really get to know your pool first.

Kim

 

[Patrick_B]

I almost always agree. There is no rush to add them.

 

[ThisGuy3675]

Thanks. I will keep my pool within the limits specified here. I may come back again if there are any issues, or perhaps when I understand the pool more and am comfortable adding borates. THANKS!!!

 

[kimkats]

Oh I hope you come back anytime. There is much to learn and share,
Kim

 

[Pyrodav]

ThisGuy, If you have not, buy a speedstir. Also your "dedicated" bottle, I found that using a clear condiment bottle works awesome. you can squeeze the water down the side of the tube without making bubbles and measure accurately the first time. Also I stole a trick from a member here and use a piece of 3/4" pvc pipe about 3ft long to extract water out of the pool. Simply put my thumb over the end until it is 18 or so inches below the water and release then thumb it again and wallllah...you have enough water to fill you squeeze bottle.

Just a couple things Ive learned from the great people here!