So. A few fish died while I was at work today, nitrites were ridiculously high. I have managed to lower them quickly with water changes, but my ph is high.. It's off the ph chart I have heh.

Is ph down any good? How often can it be used should I use it once and it's still not low enough? Any other ways to get it down?

I've read about having wood in the aquarium and I do, takes up most of the tank!

Any help would be great, I'd hate to lose more fish.