"pH swings"

hello forum, about a week ago my tanks pH was sitting at around 8.2 and when i tested it just about an hour ago it looked like it was well and truly of the scale. what could of caused this to happen.
Note:
i live in Western Australia and we have had some serious heat lately.
also i have been topping the tank up with fresh water as evaporation takes place daily.
any suggestions on keeping it constant of 8.2 or not?

Cheers, DeepSeaDiver

 

when you say off the scale, do you mean it is very much above 8.2 or off the scale below 8.2

what test kit are you using?
have you double checked the kit with either another kit or LFS test? as sometimes
evaporation can happen with the reagents in test kits, if they are not screwed down tightly, in a hot humid enviroment, which can result in concentrations of reagents increasing and strange test results (your adding a higher concentration of reagent per drop hence you get an artificially higher reading)

also - are you dosing an alkalinity buffer? or Kalkwasser ? because some of the additives to increase DKH can also increase PH?

Steve

 

i am using the test kit API and from my knowledge the kits is kept in a cool environment so im sure that is not the issue. when i refer to "off the scale" i am talking about it being around 8.8 ( i very pinkly purple colour)

i have actually only heard of the buffer just now, didnt think tanks needed it.ill have to get a test kit that tests that (if there is) and then add what i need too

thanks alot steve