hi, apologies if im in the wrong area or this is a regular question but i have a juwel 190l tank, upgrading from keeping coldwater to tropical fish, i have had the tank for 2 weeks(ish) i bought it second hand, i performed a water test last week and one this week, with a 50% change in between, my levels are reading PH 7.6 (both tests) nitrite 0(both) nitrate 5.0 and ammonia was what looks like 0 to 0.25, 0.25 at the very maximum, is the ph too high? is the ammonia level dangerous at .25? would an air pump combat the ammonia or cause more stress for the fish? i think i will replace the entire media but at this point dont have the funds to do it (juwel filter media quite expensive) appreciate the help