Distilled water trick

[rjb1211]

I slammed the pool in late October and closed it. I still have too much chlorine to get accurate pH readings.

Everything I read on here says you can dilute the pool water 1:1 with distilled water but at that ratio I still have bad readings. I had saved a post by Ben on the old forum many years ago where he said it was ok to go to 1:2 pool:distilled when chlorine was really high. When I do that my pH reading is 7.6 which is a little higher than where it was before I slammed.

Can I trust that is close enough? I do not want to run the risk of scaling over the rest of the winter and I don't really want to get the Apera PH60 just for the few times I can't use phenol red drops.

 

[Newdude]

Let's call @JoyfulNoise for a dilution answer.

I have had good luck using less drops of phenol red. I like to 'run hot' so with a swg (higher CYA/FC) I'm pretty much always at 10+.

I fill both sides of the comparator block and use 3 drops in one and 4 drops in the other. One of them, if not both of them are always back in the right color scale.

 

[duraleigh]

Can you post a set of current test results? Your sig says you have a PS234????? That kit hasn't been made for 10+ years

 

[rjb1211]

Can you post a set of current test results? Your sig says you have a PS234????? That kit hasn't been made for 10+ years

The reagents have been replaced with the Taylor equivalents many times.

TA - 100
FC - 22
CH - 330
CYA - 70
Temp - 42
pH - ?

 

[duraleigh]

No need for the digital meter, Assuming the pool is clear, I would leave everything alone.

Are you going to winterize your pool?

 

[rjb1211]

Are you going to winterize your pool?

That was done 11/1. By now the FC has usually dropped enough to test pH but we haven't had much rain and with the cover on it isn't burning off.

 

[Donldson]

That was done 11/1.

If your pool is closed then why are you messing around with the chemistry? If the water isn't circulating then you're only getting a reading of that one spot anyway, not to mention adding acid to a pool without circulation is a very bad idea...

 

[rjb1211]

If your pool is closed then why are you messing around with the chemistry? If the water isn't circulating then you're only getting a reading of that one spot anyway, not to mention adding acid to a pool without circulation is a very bad idea...

I pay close attention to CSI to avoid scaling. I pull the water for testing from the middle of the deep end. If I need to add anything I circulate the water with a submersible pump.

 

[Newdude]

You need to circulate well to make the tests valid, even more so if you have a mesh cover that accumulates rain.

 

[Texas Splash]

I can appreciate that you're tying to be proactive to avoid scale, but I would leave it alone. The cold water will make the pH rise while simultaneously bring the CSI down. No good way to perform accurate testing and chemical applications at this point. Let the pool slumber and open as soon as you can. Enoy the winter break.

 

[rjb1211]

I can appreciate that you're tying to be proactive to avoid scale, but I would leave it alone. The cold water will make the pH rise while simultaneously bring the CSI down. No good way to perform accurate testing and chemical applications at this point. Let the pool slumber and open as soon as you can. Enoy the winter break.

I understand what you are saying, but I had to replaster the pool after developing a bad case of scale one winter. That isn't going to happen again. I will be proactive.

After that bad experience I have always made sure everything was in balance over the winter. I anticipate the movement in readings over the winter and like to start at closing with TA a little high and pH a little low. About this time things have usually drifted some and I check it to ensure it is ok. This year is different in that the FC isn't dropping like it has in the past making the pH reading inaccurate.

If I make an assumption on the pH level the CSI is fine. For now I will go with that and check again in a couple of weeks.

 

[Bperry]

I understand what you are saying, but I had to replaster the pool after developing a bad case of scale one winter. That isn't going to happen again. I will be proactive.

After that bad experience I have always made sure everything was in balance over the winter. I anticipate the movement in readings over the winter and like to start at closing with TA a little high and pH a little low. About this time things have usually drifted some and I check it to ensure it is ok. This year is different in that the FC isn't dropping like it has in the past making the pH reading inaccurate.

If I make an assumption on the pH level the CSI is fine. For now I will go with that and check again in a couple of weeks.

If you’re going to do it anyway, put a sump pump down in the water and circulate the water for an hour before testing and then keep it running after adding anything. That’ll help ensure your water samples aren’t from stratified areas, even half way down the deep end.

 

[JoyfulNoise]

If the pool is covered and the water is cold (below 50F) and the FC was high at closing, it could take a very, very long time. Chlorine will hold for a very long time at low temps.

My suggestion would be to only use a 1:1 dilution with distilled water. Let the pool water sample come up to room temperature and then dilute 1:1 with distilled water. Do the pH test quickly … add the 5 drops of phenol red, cap the test vial and invert once quickly to mix. Then immediately read the color against a white background with indirect lighting (sunlight works the best). That initial color read is accurate enough. Do not wait to make the reading.

The reaction of chlorine with phenol red is fairly slow when the FC is around 10ppm or so. Above 20ppm the chlorination of phenol red is too fast to make an accurate reading.

 

[rjb1211]

Thanks for all the comments. I had failed to say that I do put a pump in the deep end and run the hose to the shallow end to circulate before drawing test water. If I add anything it’s a small amount at a time and I run that setup for 2 days to circulate.

I had also let the water come up to room temperature before testing. Next time I test I will be as quick as possible getting the read.

 

[rjb1211]

If the pool is covered and the water is cold (below 50F) and the FC was high at closing, it could take a very, very long time. Chlorine will hold for a very long time at low temps.

I just realized that is what is different this year. I normally close the pool when the water temps drops to 60 which typically occurs around mid-October here. This year it was delayed and wasn't closed until 11/1 and the water temp was nearer to 50. That explains why FC hasn't dropped the way it has in the past.