A friend's pool results, and I am not sure what to do

[sedalbj]

Thanks to this forum and my test kit, my pool is easy to handle. A friend of mine painted the inside of his concrete pool last year, and he just noticed the paint is starting to disintegrate when he brushed the sides. I asked him how he tests his pool, and he has been using trichlor and just letting it go. I told him his pH and TA were probably low, and he reluctantly let me test it.

My test results are
FC 2
pH lower than 6.8, couldn't get a read past there. it was the color of pee
CH 200
TA 30
CYA 60
(22500 gal pool concrete pool, painted, DE filter, trichlor feeder, no water feature)

Not sure where to start with this. Stop using trichlor of course, but what to balance first? Besides raise chlorine level.

Trying to make a TFP convert

 

[abycat]

technically all the test results are low except for cya.if it were me id start with pool math and figure out what you need to bring everything up to an appropriate level. my order would be fc, ph, ta, ch.

 

[mknauss]

He is going to have to make a decision. The paint will continue to disintegrate. Present paints do not work in pools.

Most important for the shell is getting the pH up. I would suggest using Borax in small amounts (assume pH of 6.8 and target 7.5) until you get a pH in the 7's. The add baking soda if necessary to get TA to 70 ppm.

 

[sedalbj]

OK. pH then TA. (and sanitizer of course). Just wasn't sure which to focus on first. After that we can address everything else. Thanks friends!!!

 

[sedalbj]

Thanks for your replies. I did him a favor and worked on his pool water today. I tried explaining the effect of Trichlor, etc etc but his eyes glazed over. He was loving just loading that puck feeder and walking away . In time he will come around I think. He is a professional painter and he insists whatever toxic brew he painted on the pool should have been ok if the pH was right.

In the meantime, I went to his house 4 times today (he is a good friend) and added borax 1/2 box at a time. He has an older pool with one return, one skimmer and one drain so it took much longer than I anticipated to fully cycle the entire pool through the filter. I assumed 1.5 hours, but I think it was more like 3 hours! When I went back for visit #4 to run tests again I realized I overshot, now his pH is too high. His TA is just barely, faintly 70. Since it was cloudy when I showed up this morning and got worse all day, and his CC was 0, I brought him up past SLAM level. I can't do the OCLT, but you know, he can't have everything. And it isn't my pool ;-)

Tomorrow I want to replace at least 4" of water and see what it does to his CYA. Then 4 more until the CYA is 30.

I'll wait a few days for the chlorine to go back down, then I will perfect his TA and pH and FC and hand it over to him. Right now, he is willing to buy a basic pool test kit so he can test pH, add Borax when needed, and drain his pool once in awhile to get rid of CYA. Hey, it's his pool.

MOST IMPORTANTLY, I really learned a lot today. I was really interested in seeing the full panel of tests, done 4 times in one day, as I added the borax. I was interested to see the CSI change and the TA gradually increase. To finish off the job and have it all nice and balanced will be a nice accomplishment for me.

 

[mknauss]

There is no reason to wait to 'cycle the pool water through the filter'. That is a myth called 'turnover'.

Most chemicals quickly disperse in water. Run the pump for 30 minutes and do a vigorous brushing and it will be fully mixed.

 

[sedalbj]

It's done. And it's perfect. I added Borax 1/2 box at a time until pH=7.2 (TA=70), then added baking soda 2 lbs at a time to adjust the TA. It took many visits and tests since the pH was so low my test wouldn't register it. I didn't want to over do it. 3 boxes of borax and 7lbs of baking soda later:::: TA 80 and pH 7.5

According to PoolMath adding 228oz of borax(3 boxes) to his pool raises TA by 20 and pH by 1.1. Can I assume Pool Math is correct and that if his pH was 7.2 after borax, and the borax should have raised it 1.1, that his pH was 6.1 before I began? Is there anything that would affect the validity of that assumption? A pH of 6.1 is bad bad bad, anything below 6.8 eats metal, right?

Is that because of trichlor pucks? His fill water was local municipal two years ago so shouldn't have been too far off. And no aeration besides swimmers and one return that just barely breaks the water surface. Makes me wonder if the 'red eyes' kids get from swimming pools isn't the chlorine (always the go to culprit) but low pH because of puck use. How many pools have dangerously low pH because of trichlor?

We have to finish addressing CH and CYA, that is in progress. Getting him on board and getting a TFP test kit seems like it may happen.

His son swam in it for the first time since I started working on it and said it is like swimming in a blanket. He loved it. The water feel is 100% better. It feels softer.

Thanks mknauss for your advice! This was a very interesting exercise for me.

 

[mknauss]

Back calculating to a pH is not very accurate. Our calculations, as the disclaimer states in Effects of Adding Chemicals, are not that accurate with pH and TA out of range. But what you did was great.

Trichlor is the culprit. Very acidic. If used, one needs to monitor TA closely and add baking soda often. And drain 1/3 of the pool about every month or so to reduce CYA build up.

Red eyes are caused by low pH and / or high CC. Chlorine has little to do with it.