tank cycling again?

shoot, my levels are allover the place and i dont understand. The only thing i can think is i recently put in about three pounds of new live rock.. (scrubbed with a brush under hot water).. my fish seem a bit irritated lately so i tested and now i know why.. heres my levels last week

ammonia 0
no2 - 0
no3- 20
ph -8
calcium 380

today:
ammonia .5
no2-0
no3 50
ph7.5
calcium 400

SG is .23

im running a skimmer and a pengiun 200 with denitrate (seachem) media bag, and regular filter.. 20 gallon long.. i dont get it, why my nitrate levels are always so hard to keep down, and now this.. my ammonia has NEVER gone over zero.. is it possible my new live rock has started cycling again? im going to do a water change of course but what can i do to up my PH and for heavens sake get that nitrate level to stay down.. Im getting an aquac remo tomorrow in place of my prizm skimmer.. my space is a bit limited so a refugium prolly wont fly..Im also wondering if i should buy a cannister filter so i can have some bioballs and extra media space for some extra carbon and purigen and whatever ... any thoughts would be greatly appreciated.. thanks

 

In the future, I wouldn't use hot water then introduce it to the tank

Could be die-off (lots of it) from the HOT water

 

dam, thats prolly it... here i was thinking i was doing the right thing by not just putting it in the tank.. i shoulda just put it directly in.. dangit

 

uh, okay.. well levels are back to zero again, except for nitrate.. very strange.. mustve been a mini atomic bomb from the liverock.. case closed :-/