Really high nitrates... Low phosphate

[Sitthanon]

Hi,

Recently started my new aquarium and now after the cycle i messured 25ppm nitrate.. did a water change and it went down a bit 15ppmish I would say. 2 days later i tested again and the nitrate were 50ppm did a water change and it barely budged. Next day(today) it's showing 100ppm. tested everything related to the cycle and it came out

0 Ammonia
0 Nitrite
0 phosphate (know that it shouldn't be zero but it is more or less, hard to tell from the test kit)
100+ nitrate (salifert only goes to 100 and it sure is 100)

new marco rocks
cycled with brightwell XLM start
new sand

Any Idé what the problem is? would like to solve it before I transfer my fish/coral from the old tank

 

[Dbichler]

Either you have nitrites and the reading is false or your water change water has nitrates. I would check my water source and if good do a 100% water change.