I finally did it!!!

[Rangeball]

Rain is a great aerator. If I need to lower my Alk, I always like to do it ahead of a rain forecast.

Whether or not you need to lower you alk depends on if the PH is increasing rapidly for you or not. If it isn't, then probably not. If it is, the lower you can get your alk within range, the slower the PH rise will tend to be.

 

[gonefishin]

I would add "unless your elevated TA causes PH increases as chlorine is less effective at higher PH levels as well as potential water clarity issues from higher PH."

I'd agree that chlorine is less effective as the Ph rises. But isn't the Ph bounce caused from low TA readings and not high readings. From my understanding high TA levels make the Ph more resistant (and sometime stubborn) to change the Ph level. High TA readings would be over 200. With a reading of 170 in a vinyl pool, I don't see any reason to make a TA change unless he's having a difficult time making a necassary change to his Ph.

dan

(Waterbear went into a little detail regarding the TA and Ph in this thread)

 

[waterbug]

She will check her PH level again tonight and if it's holding steady, she'll leave it alone fo now.

 

[Rangeball]

Chemgeek has a chart here somewhere that shows the outgassing and PH increase at different TA levels. Generally, the higher the TA, the quicker the PH rise.

This is also how it works in my vinyl IG pool. If TA get's much above 150, PH creeps up on an almost daily basis, daily if TA is 200+.

I have it at 120 now, and it is holding fairly steady, creeps up every 2-3 weeks or so.

 

[waterbug]

My numbers from the pool store - Pinpoint Computerized Water Analysis sytem are:
FC 2.8
TC 2.9
CC 0.1
pH 7.6
CYA 70
TA 99
ATA 77
CH 126

So, when I do the tests how come my chlorine reads 11 instead of about 3? The pool guy wondered if perhaps I was adding the drops too quickly and it wasn't getting enough time to react before the next drop went in? Is that Possible - how long should I wait between drops?

thanks,
waterbug

 

[Rangeball]

With FAS/DPD, I swish thoroughly after every drop.

In my experience, when you get close to the end, it will lighten quite a bit, then the last drop clears it immediately with little swishing.

 

[JasonLion]

It is fairly common for chlorine levels to fall dramatically on the way to the pool store to have the water tested. You want to have the container well rinsed, then completely filled with pool water, and kept out of sunlight to minimize this.

 

[waterbug]

I had it quite full and was at the pool store about 15 minutes after taking the sample.

by the way, if pool store is right about alkalinity being 99, is this an okay number with 7.6 ph? Pool store and I agree on 7.6 at least.

 

[JasonLion]

Alkalinity of 99 is just fine (unless you have constantly rising PH).