I guess, at this point, measure it often and see if you can find a pattern. If it's 450 now, it shouldn't go down significantly before your next water change, which should replace any used up

Thanks for everything so far but no one has really answered the main point to my question:

How do you keep pH from raising when you have to raise your kH? Or can you? I know some of you said that 8.5 isn't bad but my tank used to go from 7.9 to 8.1...

Any solutions or do you just not worry about it? Wouldn't this really affect SPS if you had a tank full of them?

To answer your question, based on my experience, toss your pH tester away and don't worry about it. I haven't checked pH since 2004 or so...
Also, to avoid any large swings, don't let the values get that low before bumping them. Then everything will be happy :)

You can add vinegar to lower the PH. Use 1ml vinegar per gallon will drop the PH by 0.3 units, that the way I had read it. You can google it to do some more research about this or read some of the articles from Randy Holmes about reef chemistry.