Using bleach vs tabs - raises ph?

[neen01]

I switched to bleach a few years ago and have realized that our ph is higher these days and i have needed to use muriatic acid to lower it. Previously it has stayed low all season and never really caused a problem.
Is that a result of switching to bleach? Does it affect the ph differently from the tabs?

Also noticed we have gotten little spots of yellow algae in the corner of the stairs last season and this season where we never had it before. It hasn't been all over just in a few shady spots. Is this maybe because the ph is running higher than it had been the years before?

 

[mikech]

There should be a net zero change in pH from using bleach, whereas pucks will lower pH (which I assume you were using). Most plaster pools seem to naturally rise, albeit slowly.

Sound like your FC is a little low. Post a full set of results so we can see what is going on. Poor circulation in those troublesome areas won't help either.

 

[YippeeSkippy]

Re: the algae spots-Have you been brushing less this year than in previous years?

 

[neen01]

There should be a net zero change in pH from using bleach, whereas pucks will lower pH (which I assume you were using). Most plaster pools seem to naturally rise, albeit slowly.

Ok I remember when we put it in they said it does naturally rise so must have been the pucks keeping it in line those first few years. I'll just keep a better eye on it going forward. Thanks!

 

[chem geek]

The Trichlor pucks are acidic so lower both pH and TA. If you didn't have to add any chemicals for either pH or TA adjustment, then you must have had plaster curing or some other source to counter the pH and TA drop. If the TA slowly dropped so you added baking soda on occasion to raise it, then that means the pH was balanced from carbon dioxide outgassing so you probably had the TA higher (in the 100-120 ppm range or higher).

With the bleach, it's close to pH neutral. There's a small amount of excess lye in it but most pH rise in pools using bleach or chlorinating liquid (or Cal-Hypo or lithium hypochlorite) comes from carbon dioxide outgassing and that can be minimized by having a lower TA target (usually not higher than 80 ppm) and a higher pH target (around 7.7 or so).