There was no Phosphate leaching in my rocks and substrate neither in my tap water. I did test after I was surprised for the result that after 75%, in almost just 24 hours!, i have way off chart Phosphate result. This is not a reocurrence problem but the very first time in my 2 year old planted tank.

But thats a good advice to check the test kit. At least, It eases me with my worries of high PO4 in my tank.

Thanks for the info!